Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study population is multiplicative and does not change over time.
An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.
Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.
Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.
Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.
A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.
A class of statistical procedures for estimating the survival function (function of time, starting with a population 100% well at a given time and providing the percentage of the population still well at later times). The survival analysis is then used for making inferences about the effects of treatments, prognostic factors, exposures, and other covariates on the function.
A nonparametric method of compiling LIFE TABLES or survival tables. It combines calculated probabilities of survival and estimates to allow for observations occurring beyond a measurement threshold, which are assumed to occur randomly. Time intervals are defined as ending each time an event occurs and are therefore unequal. (From Last, A Dictionary of Epidemiology, 1995)
The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.
Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.
The proportion of survivors in a group, e.g., of patients, studied and followed over a period, or the proportion of persons in a specified group alive at the beginning of a time interval who survive to the end of the interval. It is often studied using life table methods.
A set of techniques used when variation in several variables has to be studied simultaneously. In statistics, multivariate analysis is interpreted as any analytic method that allows simultaneous study of two or more dependent variables.
The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)
Elements of limited time intervals, contributing to particular results or situations.
Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.
In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.
The probability that an event will occur. It encompasses a variety of measures of the probability of a generally unfavorable outcome.
Factors which produce cessation of all vital bodily functions. They can be analyzed from an epidemiologic viewpoint.
Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.
Methods which attempt to express in replicable terms the extent of the neoplasm in the patient.
A range of values for a variable of interest, e.g., a rate, constructed so that this range has a specified probability of including the true value of the variable.
Period after successful treatment in which there is no appearance of the symptoms or effects of the disease.
Studies in which variables relating to an individual or group of individuals are assessed over a period of time.
All deaths reported in a given population.
Tumors or cancer of the human BREAST.
Pathological conditions involving the CARDIOVASCULAR SYSTEM including the HEART; the BLOOD VESSELS; or the PERICARDIUM.
The systems and processes involved in the establishment, support, management, and operation of registers, e.g., disease registers.
A cancer registry mandated under the National Cancer Act of 1971 to operate and maintain a population-based cancer reporting system, reporting periodically estimates of cancer incidence and mortality in the United States. The Surveillance, Epidemiology, and End Results (SEER) Program is a continuing project of the National Cancer Institute of the National Institutes of Health. Among its goals, in addition to assembling and reporting cancer statistics, are the monitoring of annual cancer incident trends and the promoting of studies designed to identify factors amenable to cancer control interventions. (From National Cancer Institute, NIH Publication No. 91-3074, October 1990)
Inhaling and exhaling the smoke of burning TOBACCO.
Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.
Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.
The worsening of a disease over time. This concept is most often used for chronic and incurable diseases where the stage of the disease is an important determinant of therapy and prognosis.
The local recurrence of a neoplasm following treatment. It arises from microscopic cells of the original neoplasm that have escaped therapeutic intervention and later become clinically visible at the original site.
Factors that can cause or prevent the outcome of interest, are not intermediate variables, and are not associated with the factor(s) under investigation. They give rise to situations in which the effects of two processes are not separated, or the contribution of causal factors cannot be separated, or the measure of the effect of exposure or risk is distorted because of its association with other factors influencing the outcome of the study.
Molecular products metabolized and secreted by neoplastic tissue and characterized biochemically in cells or body fluids. They are indicators of tumor stage and grade as well as useful for monitoring responses to treatment and predicting recurrence. Many chemical groups are represented including hormones, antigens, amino and nucleic acids, enzymes, polyamines, and specific cell membrane proteins and lipids.
The end-stage of CHRONIC RENAL INSUFFICIENCY. It is characterized by the severe irreversible kidney damage (as measured by the level of PROTEINURIA) and the reduction in GLOMERULAR FILTRATION RATE to less than 15 ml per min (Kidney Foundation: Kidney Disease Outcome Quality Initiative, 2002). These patients generally require HEMODIALYSIS or KIDNEY TRANSPLANTATION.
A group of pathological conditions characterized by sudden, non-convulsive loss of neurological function due to BRAIN ISCHEMIA or INTRACRANIAL HEMORRHAGES. Stroke is classified by the type of tissue NECROSIS, such as the anatomic location, vasculature involved, etiology, age of the affected individual, and hemorrhagic vs. non-hemorrhagic nature. (From Adams et al., Principles of Neurology, 6th ed, pp777-810)
The presence of co-existing or additional diseases with reference to an initial diagnosis or with reference to the index condition that is the subject of study. Comorbidity may affect the ability of affected individuals to function and also their survival; it may be used as a prognostic indicator for length of hospital stay, cost factors, and outcome or survival.
The return of a sign, symptom, or disease after a remission.
An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)
Individuals whose ancestral origins are in the continent of Europe.
Tumors or cancer of the PROSTATE.
A distribution in which a variable is distributed like the sum of the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another.
The ratio of two odds. The exposure-odds ratio for case control data is the ratio of the odds in favor of exposure among cases to the odds in favor of exposure among noncases. The disease-odds ratio for a cohort or cross section is the ratio of the odds in favor of disease among the exposed to the odds in favor of disease among the unexposed. The prevalence-odds ratio refers to an odds ratio derived cross-sectionally from studies of prevalent cases.
NECROSIS of the MYOCARDIUM caused by an obstruction of the blood supply to the heart (CORONARY CIRCULATION).
Therapy for the insufficient cleansing of the BLOOD by the kidneys based on dialysis and including hemodialysis, PERITONEAL DIALYSIS, and HEMODIAFILTRATION.
An imbalance between myocardial functional requirements and the capacity of the CORONARY VESSELS to supply sufficient blood flow. It is a form of MYOCARDIAL ISCHEMIA (insufficient blood supply to the heart muscle) caused by a decreased capacity of the coronary vessels.
Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.
Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.
Tumors or cancer of the COLON or the RECTUM or both. Risk factors for colorectal cancer include chronic ULCERATIVE COLITIS; FAMILIAL POLYPOSIS COLI; exposure to ASBESTOS; and irradiation of the CERVIX UTERI.
Tumors or cancer of the LUNG.
Transfer of a neoplasm from its primary site to lymph nodes or to distant parts of the body by way of the lymphatic system.
Research techniques that focus on study designs and data gathering methods in human and animal populations.
The physiological period following the MENOPAUSE, the permanent cessation of the menstrual life.
Regular course of eating and drinking adopted by a person or animal.
Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS).
A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (VENTRICULAR DYSFUNCTION), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as MYOCARDIAL INFARCTION.
The confinement of a patient in a hospital.
New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.
Persons living in the United States having origins in any of the black groups of Africa.
Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.
A malignant epithelial tumor with a glandular organization.
The frequency of different ages or age groups in a given population. The distribution may refer to either how many or what proportion of the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.
A beverage made from ground COFFEA beans (SEEDS) infused in hot water. It generally contains CAFFEINE and THEOPHYLLINE unless it is decaffeinated.
Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc.
Behaviors associated with the ingesting of alcoholic beverages, including social drinking.
A subclass of DIABETES MELLITUS that is not INSULIN-responsive or dependent (NIDDM). It is characterized initially by INSULIN RESISTANCE and HYPERINSULINEMIA; and eventually by GLUCOSE INTOLERANCE; HYPERGLYCEMIA; and overt diabetes. Type II diabetes mellitus is no longer considered a disease exclusively found in adults. Patients seldom develop KETOSIS but often exhibit OBESITY.
The treatment of a disease or condition by several different means simultaneously or sequentially. Chemoimmunotherapy, RADIOIMMUNOTHERAPY, chemoradiotherapy, cryochemotherapy, and SALVAGE THERAPY are seen most frequently, but their combinations with each other and surgery are also used.
Drug regimens, for patients with HIV INFECTIONS, that aggressively suppress HIV replication. The regimens usually involve administration of three or more different drugs including a protease inhibitor.
A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.
The number of CD4-POSITIVE T-LYMPHOCYTES per unit volume of BLOOD. Determination requires the use of a fluorescence-activated flow cytometer.
A heterogeneous group of disorders characterized by HYPERGLYCEMIA and GLUCOSE INTOLERANCE.
A food group comprised of EDIBLE PLANTS or their parts.
Conditional probability of exposure to a treatment given observed covariates.
Drug therapy given to augment or stimulate some other form of treatment such as surgery or radiation therapy. Adjuvant chemotherapy is commonly used in the therapy of cancer and can be administered before or after the primary treatment.
Extensive collections, reputedly complete, of facts and data garnered from material of a specialized subject area and made available for analysis and application. The collection can be automated by various contemporary methods for retrieval. The concept should be differentiated from DATABASES, BIBLIOGRAPHIC which is restricted to collections of bibliographic references.
The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.
Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.
Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor.
Individuals whose ancestral origins are in the continent of Africa.
Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.
Continuance of life or existence especially under adverse conditions; includes methods and philosophy of survival.
The study of chance processes or the relative frequency characterizing a chance process.
The concept covering the physical and mental conditions of women.
Acquired or learned food preferences.
A glycoprotein that is a kallikrein-like serine proteinase and an esterase, produced by epithelial cells of both normal and malignant prostate tissue. It is an important marker for the diagnosis of prostate cancer.
Typical way of life or manner of living characteristic of an individual or group. (From APA, Thesaurus of Psychological Index Terms, 8th ed)
Fractures of the FEMUR HEAD; the FEMUR NECK; (FEMORAL NECK FRACTURES); the trochanters; or the inter- or subtrochanteric region. Excludes fractures of the acetabulum and fractures of the femoral shaft below the subtrochanteric region (FEMORAL FRACTURES).
Tumors or cancer of the LIVER.
Conditions or pathological processes associated with the disease of diabetes mellitus. Due to the impaired control of BLOOD GLUCOSE level in diabetic patients, pathological processes develop in numerous tissues and organs including the EYE, the KIDNEY, the BLOOD VESSELS, and the NERVE TISSUE.
Social and economic factors that characterize the individual or group within the social structure.
A measure of the quality of health care by assessment of unsuccessful results of management and procedures used in combating disease, in individual cases or series.
The age, developmental stage, or period of life at which a disease or the initial symptoms or manifestations of a disease appear in an individual.
Complete or partial surgical removal of the prostate. Three primary approaches are commonly employed: suprapubic - removal through an incision above the pubis and through the urinary bladder; retropubic - as for suprapubic but without entering the urinary bladder; and transurethral (TRANSURETHRAL RESECTION OF PROSTATE).
Works about clinical trials that involve at least one test treatment and one control treatment, concurrent enrollment and follow-up of the test- and control-treated groups, and in which the treatments to be administered are selected by a random process, such as the use of a random-numbers table.
The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.
A country spanning from central Asia to the Pacific Ocean.
A carcinoma derived from stratified SQUAMOUS EPITHELIAL CELLS. It may also occur in sites where glandular or columnar epithelium is normally present. (From Stedman, 25th ed)
Tumors or cancer of the OVARY. These neoplasms can be benign or malignant. They are classified according to the tissue of origin, such as the surface EPITHELIUM, the stromal endocrine cells, and the totipotent GERM CELLS.
Cytoplasmic proteins that bind estrogens and migrate to the nucleus where they regulate DNA transcription. Evaluation of the state of estrogen receptors in breast cancer patients has become clinically important.
Elements of residence that characterize a population. They are applicable in determining need for and utilization of health services.
Agents used to treat AIDS and/or stop the spread of the HIV infection. These do not include drugs used to treat symptoms or opportunistic infections associated with AIDS.
An acquired organic mental disorder with loss of intellectual abilities of sufficient severity to interfere with social or occupational functioning. The dysfunction is multifaceted and involves memory, behavior, personality, judgment, attention, spatial relations, language, abstract thought, and other executive functions. The intellectual decline is usually progressive, and initially spares the level of consciousness.
The use of statistical and mathematical methods to analyze biological observations and phenomena.
The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.
The fleshy or dry ripened ovary of a plant, enclosing the seed or seeds.
Tumors or cancer of ENDOMETRIUM, the mucous lining of the UTERUS. These neoplasms can be benign or malignant. Their classification and grading are based on the various cell types and the percent of undifferentiated cells.
Histochemical localization of immunoreactive substances using labeled antibodies as reagents.
Works about controlled studies which are planned and carried out by several cooperating institutions to assess certain variables and outcomes in specific patient populations, for example, a multicenter study of congenital anomalies in children.
A systematic collection of factual data pertaining to health and disease in a human population within a given geographic area.
Tumors or cancer of the STOMACH.
Systematic collections of factual data pertaining to the diet of a human population within a given geographic area.
Summarizing techniques used to describe the pattern of mortality and survival in populations. These methods can be applied to the study not only of death, but also of any defined endpoint such as the onset of disease or the occurrence of disease complications.
A primary malignant neoplasm of epithelial liver cells. It ranges from a well-differentiated tumor with EPITHELIAL CELLS indistinguishable from normal HEPATOCYTES to a poorly differentiated neoplasm. The cells may be uniform or markedly pleomorphic, or form GIANT CELLS. Several classification schemes have been suggested.
Methods which attempt to express in replicable terms the level of CELL DIFFERENTIATION in neoplasms as increasing ANAPLASIA correlates with the aggressiveness of the neoplasm.
The use of hormonal agents with estrogen-like activity in postmenopausal or other estrogen-deficient women to alleviate effects of hormone deficiency, such as vasomotor symptoms, DYSPAREUNIA, and progressive development of OSTEOPOROSIS. This may also include the use of progestational agents in combination therapy.
Tumors or cancer of the ESOPHAGUS.
Country located in EUROPE. It is bordered by the NORTH SEA, BELGIUM, and GERMANY. Constituent areas are Aruba, Curacao, Sint Maarten, formerly included in the NETHERLANDS ANTILLES.
Specific proteins found in or on cells of progesterone target tissues that specifically combine with progesterone. The cytosol progesterone-receptor complex then associates with the nucleic acids to initiate protein synthesis. There are two kinds of progesterone receptors, A and B. Both are induced by estrogen and have short half-lives.
A carotenoid that is a precursor of VITAMIN A. It is administered to reduce the severity of photosensitivity reactions in patients with erythropoietic protoporphyria (PORPHYRIA, ERYTHROPOIETIC). (From Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Engewood, CO, 1995.)
Former members of the armed services.
Ability of neoplasms to infiltrate and actively destroy surrounding tissue.
A graphic means for assessing the ability of a screening test to discriminate between healthy and diseased persons; may also be used in other studies, e.g., distinguishing stimuli responses as to a faint stimuli or nonstimuli.
Pathological processes of CORONARY ARTERIES that may derive from a congenital abnormality, atherosclerotic, or non-atherosclerotic cause.
The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.
The volume of water filtered out of plasma through glomerular capillary walls into Bowman's capsules per unit of time. It is considered to be equivalent to INULIN clearance.
A heterogeneous aggregate of at least three distinct histological types of lung cancer, including SQUAMOUS CELL CARCINOMA; ADENOCARCINOMA; and LARGE CELL CARCINOMA. They are dealt with collectively because of their shared treatment strategy.
Application of statistical procedures to analyze specific observed or assumed facts from a particular study.
Tumors or cancers of the KIDNEY.
The use of two or more chemicals simultaneously or sequentially in the drug therapy of neoplasms. The drugs need not be in the same dosage form.
Research aimed at assessing the quality and effectiveness of health care as measured by the attainment of a specified end result or outcome. Measures include parameters such as improved health, lowered morbidity or mortality, and improvement of abnormal states (such as elevated blood pressure).
A single nucleotide variation in a genetic sequence that occurs at appreciable frequency in the population.
The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.
Federal program, created by Public Law 89-97, Title XVIII-Health Insurance for the Aged, a 1965 amendment to the Social Security Act, that provides health insurance benefits to persons over the age of 65 and others eligible for Social Security benefits. It consists of two separate but coordinated programs: hospital insurance (MEDICARE PART A) and supplementary medical insurance (MEDICARE PART B). (Hospital Administration Terminology, AHA, 2d ed and A Discursive Dictionary of Health Care, US House of Representatives, 1976)
Radiotherapy given to augment some other form of treatment such as surgery or chemotherapy. Adjuvant radiotherapy is commonly used in the therapy of cancer and can be administered before or after the primary treatment.
Unexpected rapid natural death due to cardiovascular collapse within one hour of initial symptoms. It is usually caused by the worsening of existing heart diseases. The sudden onset of symptoms, such as CHEST PAIN and CARDIAC ARRHYTHMIAS, particularly VENTRICULAR TACHYCARDIA, can lead to the loss of consciousness and cardiac arrest followed by biological death. (from Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005)
Irreversible cessation of all bodily functions, manifested by absence of spontaneous breathing and total loss of cardiovascular and cerebral functions.
Tumors or cancer of the PANCREAS. Depending on the types of ISLET CELLS present in the tumors, various hormones can be secreted: GLUCAGON from PANCREATIC ALPHA CELLS; INSULIN from PANCREATIC BETA CELLS; and SOMATOSTATIN from the SOMATOSTATIN-SECRETING CELLS. Most are malignant except the insulin-producing tumors (INSULINOMA).
Neoplasms of the intracranial components of the central nervous system, including the cerebral hemispheres, basal ganglia, hypothalamus, thalamus, brain stem, and cerebellum. Brain neoplasms are subdivided into primary (originating from brain tissue) and secondary (i.e., metastatic) forms. Primary neoplasms are subdivided into benign and malignant forms. In general, brain tumors may also be classified by age of onset, histologic type, or presenting location in the brain.
Raw and processed or manufactured milk and milk-derived products. These are usually from cows (bovine) but are also from goats, sheep, reindeer, and water buffalo.
A plasma protein that circulates in increased amounts during inflammation and after tissue damage.
Persons who have experienced a prolonged survival after serious disease or who continue to live with a usually life-threatening condition as well as family members, significant others, or individuals surviving traumatic life events.
The transfer of a neoplasm from one organ or part of the body to another remote from the primary site.
An operating division of the US Department of Health and Human Services. It is concerned with the overall planning, promoting, and administering of programs pertaining to health and medical research. Until 1995, it was an agency of the United States PUBLIC HEALTH SERVICE.
The last menstrual period. Permanent cessation of menses (MENSTRUATION) is usually defined after 6 to 12 months of AMENORRHEA in a woman over 45 years of age. In the United States, menopause generally occurs in women between 48 and 55 years of age.
A group of people with a common cultural heritage that sets them apart from others in a variety of social relationships.
An important aggregate factor in epidemiological studies of women's health. The concept usually includes the number and timing of pregnancies and their outcomes, the incidence of breast feeding, and may include age of menarche and menopause, regularity of menstruation, fertility, gynecological or obstetric problems, or contraceptive usage.
A heterogeneous group of sporadic or hereditary carcinoma derived from cells of the KIDNEYS. There are several subtypes including the clear cells, the papillary, the chromophobe, the collecting duct, the spindle cells (sarcomatoid), or mixed cell-type carcinoma.
Graphical representation of a statistical model containing scales for calculating the prognostic weight of a value for each individual variable. Nomograms are instruments that can be used to predict outcomes using specific clinical parameters. They use ALGORITHMS that incorporate several variables to calculate the predicted probability that a patient will achieve a particular clinical endpoint.
Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care. (Dictionary of Health Services Management, 2d ed)
A status with BODY WEIGHT that is grossly above the acceptable or desirable weight, usually due to accumulation of excess FATS in the body. The standards may vary with age, sex, genetic or cultural background. In the BODY MASS INDEX, a BMI greater than 30.0 kg/m2 is considered obese, and a BMI greater than 40.0 kg/m2 is considered morbidly obese (MORBID OBESITY).
The application of STATISTICS to biological systems and organisms involving the retrieval or collection, analysis, reduction, and interpretation of qualitative and quantitative data.
A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.
The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.
A latent susceptibility to disease at the genetic level, which may be activated under certain conditions.
Ongoing scrutiny of a population (general population, study population, target population, etc.), generally using methods distinguished by their practicability, uniformity, and frequently their rapidity, rather than by complete accuracy.
Products in capsule, tablet or liquid form that provide dietary ingredients, and that are intended to be taken by mouth to increase the intake of nutrients. Dietary supplements can include macronutrients, such as proteins, carbohydrates, and fats; and/or MICRONUTRIENTS, such as VITAMINS; MINERALS; and PHYTOCHEMICALS.
Abnormal growths of tissue that follow a previous neoplasm but are not metastases of the latter. The second neoplasm may have the same or different histological type and can occur in the same or different organs as the previous neoplasm but in all cases arises from an independent oncogenic event. The development of the second neoplasm may or may not be related to the treatment for the previous neoplasm since genetic risk or predisposing factors may actually be the cause.
Any deviation of results or inferences from the truth, or processes leading to such deviation. Bias can result from several sources: one-sided or systematic variations in measurement from the true value (systematic error); flaws in study design; deviation of inferences, interpretations, or analyses based on flawed data or data collection; etc. There is no sense of prejudice or subjectivity implied in the assessment of bias under these conditions.
Dialysis fluid being introduced into and removed from the peritoneal cavity as either a continuous or an intermittent procedure.
Lack of perfusion in the EXTREMITIES resulting from atherosclerosis. It is characterized by INTERMITTENT CLAUDICATION, and an ANKLE BRACHIAL INDEX of 0.9 or less.
Tumors or cancer of the COLON.
Compounds that inhibit HMG-CoA reductases. They have been shown to directly lower cholesterol synthesis.
The survival of a graft in a host, the factors responsible for the survival and the changes occurring within the graft during growth in the host.
Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.
Educational attainment or level of education of individuals.
Breaks in bones.
The exposure to potentially harmful chemical, physical, or biological agents that occurs as a result of one's occupation.
Diseases caused by factors involved in one's employment.
The transference of a kidney from one human or animal to another.
A province of Canada on the Pacific coast. Its capital is Victoria. The name given in 1858 derives from the Columbia River which was named by the American captain Robert Gray for his ship Columbia which in turn was named for Columbus. (From Webster's New Geographical Dictionary, 1988, p178 & Room, Brewer's Dictionary of Names, 1992, p81-2)
Pathological processes of the KIDNEY or its component tissues.
Individuals whose ancestral origins are in the southeastern and eastern areas of the Asian continent.
A group of islands in Polynesia, in the north central Pacific Ocean, comprising eight major and 114 minor islands, largely volcanic and coral. Its capital is Honolulu. It was first reached by Polynesians about 500 A.D. It was discovered and named the Sandwich Islands in 1778 by Captain Cook. The islands were united under the rule of King Kamehameha 1795-1819 and requested annexation to the United States in 1893 when a provisional government was set up. Hawaii was established as a territory in 1900 and admitted as a state in 1959. The name is from the Polynesian Owhyhii, place of the gods, with reference to the two volcanoes Mauna Kea and Mauna Loa, regarded as the abode of the gods. (From Webster's New Geographical Dictionary, 1988, p493 & Room, Brewer's Dictionary of Names, 1992, p2330)
An adenocarcinoma producing mucin in significant amounts. (From Dorland, 27th ed)
An infant during the first month after birth.
A malignant neoplasm made up of epithelial cells tending to infiltrate the surrounding tissues and give rise to metastases. It is a histological type of neoplasm but is often wrongly used as a synonym for "cancer." (From Dorland, 27th ed)
The largest country in North America, comprising 10 provinces and three territories. Its capital is Ottawa.
The proportion of patients with a particular disease during a given year per given unit of population.
A performance measure for rating the ability of a person to perform usual activities, evaluating a patient's progress after a therapeutic procedure, and determining a patient's suitability for therapy. It is used most commonly in the prognosis of cancer therapy, usually after chemotherapy and customarily administered before and after therapy. It was named for Dr. David A. Karnofsky, an American specialist in cancer chemotherapy.
The quantity of measurable virus in a body fluid. Change in viral load, measured in plasma, is sometimes used as a SURROGATE MARKER in disease progression.
Neoplasms composed of glandular tissue, an aggregation of epithelial cells that elaborate secretions, and of any type of epithelium itself. The concept does not refer to neoplasms located in the various glands or in epithelial tissue.
Professionals qualified by graduation from an accredited school of nursing and by passage of a national licensing examination to practice nursing. They provide services to patients requiring assistance in recovering or maintaining their physical or mental health.
Groups of individuals whose putative ancestry is from native continental populations based on similarities in physical appearance.
A malignant neoplasm derived from cells that are capable of forming melanin, which may occur in the skin of any part of the body, in the eye, or, rarely, in the mucous membranes of the genitalia, anus, oral cavity, or other sites. It occurs mostly in adults and may originate de novo or from a pigmented nevus or malignant lentigo. Melanomas frequently metastasize widely, and the regional lymph nodes, liver, lungs, and brain are likely to be involved. The incidence of malignant skin melanomas is rising rapidly in all parts of the world. (Stedman, 25th ed; from Rook et al., Textbook of Dermatology, 4th ed, p2445)
Breaks in bones resulting from low bone mass and microarchitectural deterioration characteristic of OSTEOPOROSIS.
A repeat operation for the same condition in the same patient due to disease progression or recurrence, or as followup to failed previous surgery.
Computer-based representation of physical systems and phenomena such as chemical processes.
Criteria and standards used for the determination of the appropriateness of the inclusion of patients with specific conditions in proposed treatment plans and the criteria used for the inclusion of subjects in various clinical trials and other research protocols.

Microvascular loops and networks as prognostic indicators in choroidal and ciliary body melanomas. (1/14874)

BACKGROUND: Malignant melanoma of the ciliary body and choroid of the eye is a tumor that disseminates frequently, and 50% of the diagnosed patients die within 10 years. We investigated the hypothesis that, by histopathologic analysis of the arrangement of microvessels (i.e., small blood vessels) in loops and networks, we might be able to differentiate better those patients with a favorable prognosis from those with a poor prognosis. METHODS: We conducted a population-based, retrospective cohort study of melanoma-specific and all-cause mortality for 167 consecutive patients who had an eye surgically removed because of malignant choroidal or ciliary body melanoma during the period from 1972 through 1981. Microvascular loops and networks were evaluated independently by two pathologists who were unaware of patient outcome. RESULTS: Microvascular patterns could be assessed in 134 (80%) of 167 melanoma specimens. The 10-year probability of melanoma-specific survival was worse if microvascular loops (0.45 versus 0.83; two-sided P<.0001) and networks (0.41 versus 0.72, two-sided P<.0001) were present. In multivariate Cox regression analysis of melanoma-specific survival, the hazard ratios were 1.66 (95% confidence interval [CI] = 1.19-2.30) for the presence of loops and networks as a combined three-category variable, 2.36 (95% CI = 1.37-4.05) for the presence of epithelioid cells, 1.11 (95% CI = 1.03-1.19) for the largest basal tumor diameter (evaluated as a continuous variable), and 2.14 (95% CI = 1.25-3.67) for ciliary body involvement. CONCLUSIONS: Patients with malignant uveal melanoma who have a favorable prognosis can be distinguished from those with a poor prognosis by histopathologic analysis of microvascular patterns in uveal melanoma tumor specimens.  (+info)

Effects of calcium-channel blockade in older patients with diabetes and systolic hypertension. Systolic Hypertension in Europe Trial Investigators. (2/14874)

BACKGROUND: Recent reports suggest that calcium-channel blockers may be harmful in patients with diabetes and hypertension. We previously reported that antihypertensive treatment with the calcium-channel blocker nitrendipine reduced the risk of cardiovascular events. In this post hoc analysis, we compared the outcome of treatment with nitrendipine in diabetic and nondiabetic patients. METHODS: After stratification according to center, sex, and presence or absence of previous cardiovascular complications, 4695 patients (age, > or =60 years) with systolic blood pressure of 160 to 219 mm Hg and diastolic pressure below 95 mm Hg were randomly assigned to receive active treatment or placebo. Active treatment consisted of nitrendipine (10 to 40 mg per day) with the possible addition or substitution of enalapril (5 to 20 mg per day) or hydrochlorothiazide (12.5 to 25 mg per day) or both, titrated to reduce the systolic blood pressure by at least 20 mm Hg and to less than 150 mm Hg. In the control group, matching placebo tablets were administered similarly. RESULTS: At randomization, 492 patients (10.5 percent) had diabetes. After a median follow-up of two years, the systolic and diastolic blood pressures in the placebo and active-treatment groups differed by 8.6 and 3.9 mm Hg, respectively, among the diabetic patients. Among the 4203 patients without diabetes, systolic and diastolic pressures differed by 10.3 and 4.5 mm Hg, respectively, in the two groups. After adjustment for possible confounders, active treatment was found to have reduced overall mortality by 55 percent (from 45.1 deaths per 1000 patients to 26.4 deaths per 1000 patients), mortality from cardiovascular disease by 76 percent, all cardiovascular events combined by 69 percent, fatal and nonfatal strokes by 73 percent, and all cardiac events combined by 63 percent in the group of patients with diabetes. Among the nondiabetic patients, active treatment decreased all cardiovascular events combined by 26 percent and fatal and nonfatal strokes by 38 percent. In the group of patients receiving active treatment, reductions in overall mortality, mortality from cardiovascular disease, and all cardiovascular events were significantly larger among the diabetic patients than among the nondiabetic patients (P=0.04, P=0.02, and P=0.01, respectively). CONCLUSIONS: Nitrendipine-based antihypertensive therapy is particularly beneficial in older patients with diabetes and isolated systolic hypertension. Thus, our findings do not support the hypothesis that the use of long-acting calcium-channel blockers may be harmful in diabetic patients.  (+info)

Association between age and survival following major amputation. The Scottish Vascular Audit Group. (3/14874)

OBJECTIVES: To determine whether age is associated with survival following major amputation and whether this association is independent or simply reflects selection bias in amputation level. DESIGN AND MATERIALS: Computer linkage of routine discharge and death data on the 2759 patients undergoing major amputation in Scotland between 1989 and 1993 for peripheral arterial disease. METHODS: Cox's proportional hazards model and multivariate logistic regression analysis using death as the outcome variable and age, sex, urgency, amputation level and recent arterial reconstructive surgery as predictor variables. RESULTS: Proximal amputation was more common in older patients. Survival was associated with both age (p < 0.001) and amputation level (p < 0.001). Age was an independent predictor of death at 30 days (p < 0.0001), 6 months (p < 0.001), 12 months (p < 0.0001) and 2 years (p < 0.0001) postoperation. CONCLUSIONS: Survival following amputation was poor, with only half the patients alive at 2 years. Above-knee amputation was associated with poorer survival, presumably due to the presence of more severe and widespread disease, and was undertaken more commonly in older patients. However, age remained a predictor of survival after adjustment for amputation level. Higher early mortality suggest that a worse prognosis in elderly patients cannot be attributed wholly to actuarial considerations.  (+info)

Prognostic value of ECG findings for total, cardiovascular disease, and coronary heart disease death in men and women. (4/14874)

OBJECTIVE: To study abnormalities in the resting ECG as independent predictors for all cause, cardiovascular disease (CVD), and coronary heart disease (CHD) mortality in a population based random sample of men and women, and to explore whether their prognostic value is different between sexes. DESIGN AND SUBJECTS: An age and sex stratified random sample was selected from the total Belgian population aged 25 to 74 years. Baseline data were gathered and resting ECGs were classified according to Minnesota code criteria. The sample was then followed for at least 10 years with respect to cause specific death. Results are based on observations from 5208 men and 4746 women free from prevalent CHD at the start of the follow up period. RESULTS: Although the prevalence of major abnormalities in general was comparable between sexes, women had more ischaemic findings, ST segment changes, and abnormal T waves on their baseline ECG, while men showed more arrhythmias, bundle branch blocks, and left ventricular hypertrophy. Fitting the multiplicative effect on subsequent mortality between all ECG classifications under study and sex indicated that the prognostic value of ECG changes was equal in women and men. Independently of other risk factors and other major ECG changes, almost all ECG classifications were significantly related to all cause, CVD, and CHD mortality. The most predictive ECG findings for CVD death were ST segment depression (risk ratio (RR) 4.71), major ECG findings (RR 3.26), left ventricular hypertrophy (RR 2.79), bundle branch blocks (RR 2.58), T wave flattening (RR 2.47), ischaemic ECG findings (RR 2.35), and arrhythmias (RR 2.15). The prognostic value of major ECG findings for CVD and CHD death was more powerful than well established cardiovascular risk factors. CONCLUSIONS: Abnormalities in the baseline ECG are strongly associated with subsequent all cause, CVD, and CHD mortality. Their predictive value was similar for men and women.  (+info)

Recurrence in affective disorder: analyses with frailty models. (5/14874)

The risk of recurrence in affective disorder is influenced by the number of prior episodes and by a person's tendency toward recurrence. Newly developed frailty models were used to estimate the effect of the number of episodes on the rate of recurrence, taking into account individual frailty toward recurrence. The study base was the Danish psychiatric case register of all hospital admissions for primary affective disorder in Denmark during 1971-1993. A total of 20,350 first-admission patients were discharged with a diagnosis of major affective disorder. For women with unipolar disorder and for all kinds of patients with bipolar disorder, the rate of recurrence was affected by the number of prior episodes even when the effect was adjusted for individual frailty toward recurrence. No effect of episodes but a large effect of the frailty parameter was found for unipolar men. The authors concluded that the risk of recurrence seems to increase with the number of episodes of bipolar affective disorder in general and for women with unipolar disorder.  (+info)

Influence of a family history of cancer within and across multiple sites on patterns of cancer mortality risk for women. (6/14874)

A case-control study nested within a large cohort, the American Cancer Society Cancer Prevention Study-1, was conducted to test associations between a family history of cancer and cancer mortality in women. By using logistic regression, the authors analyzed family history, as reported by 429,483 women enrolled in 1959, relative to subsequent mortality through 1972 from cancer within and across multiple sites. The associations between family history and cancer mortality were generally stronger within cancer sites than across cancer sites. Within-site associations were found for breast cancer (odds ratio (OR) = 1.9), colorectal cancer (OR = 1.6), stomach cancer (OR = 1.9), and lung cancer (OR = 1.7). Across-site associations were observed for a family history of 1) breast cancer as a risk factor for ovarian cancer mortality (OR = 1.6), 2) stomach cancer as a risk factor for ovarian cancer mortality (OR = 1.5), and 3) uterine cancer as a risk factor for pancreatic cancer mortality (OR = 1.6). A general pattern of positive associations was observed between a family history of cancer at several sites and subsequent death from pancreatic cancer. These findings support the growing body of evidence from cancer genetics suggesting that inherited cancer-susceptibility genes increase the risk for cancer at many sites and are not specific to cancer risk within a single site.  (+info)

Prognostic significance of extent of disease in bone in patients with androgen-independent prostate cancer. (7/14874)

PURPOSE: To evaluate the prognostic significance of a bone scan index (BSI) based on the weighted proportion of tumor involvement in individual bones, in relation to other factors and to survival in patients with androgen-independent prostate cancer. PATIENTS AND METHODS: Baseline radionuclide bone scans were reviewed in 191 assessable patients with androgen-independent disease who were enrolled onto an open, randomized trial of liarozole versus prednisone. The extent of skeletal involvement was assessed by scoring each scan using the BSI and independently according to the number of metastatic lesions. The relationship of the scored bone involvement to other known prognostic factors was explored in single- and multiple-variable analyses. RESULTS: In single-variable analyses, the pretreatment factors found to be associated with survival were age (P = .0446), performance status (P = .0005), baseline prostate-specific antigen (P = .0001), hemoglobin (P = .0001), alkaline phosphatase (P = .0002), AST (P = .0021), lactate dehydrogenase (P = .0001), and treatment (P = .0098). The extent of osseous disease was significant using both the BSI (P = .0001) and the number of lesions present (P = .0001). In multiple-variable proportional hazards analyses, only BSI, age, hemoglobin, lactate dehydrogenase, and treatment arm were associated with survival. When the patient population was divided into three equal groups, with BSI values of < 1.4%, 1.4% to 5.1%, and > 5.1%, median survivals of 18.3, 15.5, and 8.1 months, respectively, were observed (P = .0079). CONCLUSION: The BSI quantifies the extent of skeletal involvement by tumor. It allows the identification of patients with distinct prognoses for stratification in clinical trials. Further study is needed to assess the utility of serial BSI determinations in monitoring treatment effects. The BSI may be particularly useful in the evaluation of agents for which prostate-specific antigen changes do not reflect clinical outcomes accurately.  (+info)

Hematocrit level and associated mortality in hemodialysis patients. (8/14874)

Although a number of clinical studies have shown that increased hematocrits are associated with improved outcomes in terms of cognitive function, reduced left ventricular hypertrophy, increased exercise tolerance, and improved quality of life, the optimal hematocrit level associated with survival has yet to be determined. The association between hematocrit levels and patient mortality was retrospectively studied in a prevalent Medicare hemodialysis cohort on a national scale. All patients survived a 6-mo entry period during which their hematocrit levels were assessed, from July 1 through December 31, 1993, with follow-up from January 1 through December 31, 1994. Patient comorbid conditions relative to clinical events and severity of disease were determined from Medicare claims data and correlated with the entry period hematocrit level. After adjusting for medical diseases, our results showed that patients with hematocrit levels less than 30% had significantly higher risk of all-cause (12 to 33%) and cause-specific death, compared to patients with hematocrits in the 30% to less than 33% range. Without severity of disease adjustment, patients with hematocrit levels of 33% to less than 36% appear to have the lowest risk for all-cause and cardiac mortality. After adjusting for severity of disease, the impact of hematocrit levels of 33% to less than 36% is vulnerable to the patient sample size but also demonstrates a further 4% reduced risk of death. Overall, these findings suggest that sustained increases in hematocrit levels are associated with improved patient survival.  (+info)

As stated above, you can use the survreg function. A note though: this is not strictly a Cox PH model, but rather location-scale models. Using the default log-transformation, this is the aft model. In the case of the exponential distribution, the proportional hazards and aft model are equivalent, so if distribution is set to exponential, this is a proportional hazards model with an exponential baseline. Likewise, if a baseline Weibull distribution aft model is used, the parameter estimates are just a linear transformation of those used in the proportional hazards model with Weibull baseline distribution. But in general, survreg does not fit a Cox PH model. If a semi-parametric model is desired, as found implemented in intcox, a word of caution: there are several issues with the current version of intcox (algorithm typically prematurely terminates significantly far from the MLE, fails outright with uncensored observations, no standard errors automatically presented). A new alternative that you ...
This command performs Cox-Proportional Hazards and Extended Cox-Proportional Hazards survival analysis. This form of survival analysis relates covariates to failure through hazard ratios. A covariate with a hazard ratio greater than one causes failure. A covariate with a hazard ratio less than one improves survival. Some of the subjects may be unavailable prior to failure; the term censored is applied to them. COXPH is especially constructed to deal with this situation. Statistics showing the risk set by group and time can be written to an OUTTABLE for later formatting.. Syntax ...
Background: Physical activity (PA) is considered a cornerstone of diabetes mellitus management to prevent complications, but conclusive evidence is lacking. Methods: This prospective cohort study and meta-analysis of existing studies investigated the association between PA and mortality in individuals with diabetes. In the EPIC study (European Prospective Investigation Into Cancer and Nutrition), a cohort was defined of 5859 individuals with diabetes at baseline. Associations of leisure-time and total PA and walking with cardiovascular disease (CVD) and total mortality were studied using multivariable Cox proportional hazards regression models. Fixed-and random-effects meta-analyses of prospective studies published up to December 2010 were pooled with inverse variance weighting. Results: In the prospective analysis, total PA was associated with lower risk of CVD and total mortality. Compared with physically inactive persons, the lowest mortality risk was observed in moderately active persons: ...
We explore the benefits of applying a new proportional hazard model to analyze survival of breast cancer patients. As a parametric model, the hypertabastic survival model offers a closer fit to experimental data than Cox regression, and furthermore provides explicit survival and hazard functions which can be used as additional tools in the survival analysis. In addition, one of our main concerns is utilization of multiple gene expression variables. Our analysis treats the important issue of interaction of different gene signatures in the survival analysis. The hypertabastic proportional hazards model was applied in survival analysis of breast cancer patients. This model was compared, using statistical measures of goodness of fit, with models based on the semi-parametric Cox proportional hazards model and the parametric log-logistic and Weibull models. The explicit functions for hazard and survival were then used to analyze the dynamic behavior of hazard and survival functions. The hypertabastic model
BackgroundRadiotherapy is an effective treatment for intermediate/high-risk locally-advanced prostate cancer, however, |30% of patients relapse within five years. Clinicopathological parameters currently fail to identify patients prone to systemic relapse and those whom treatment intensification may be beneficial. The purpose of this study was to independently validate the performance of a 70-gene Metastatic Assay in a cohort of diagnostic biopsies from patients treated with radical radiotherapy and androgen deprivation therapy (ADT).Patients & MethodsA bridging cohort of prostate cancer diagnostic biopsy specimens was profiled to enable optimization of the Metastatic Assay threshold prior to further independent clinical validation in a cohort of diagnostic biopsies from patients treated with radical radiotherapy and ADT. Multivariable Cox proportional hazard regression analysis was used to assess assay performance in predicting biochemical failure-free survival (BFFS) and metastasis-free survival (MFS)
This course discusses survival analysis concepts with an emphasis on health care problems. The course focuses on the Cox proportional hazards model, not the parametric models, and is not designed for predictive modelers.
This course discusses survival analysis concepts with an emphasis on health care problems. The course focuses on the Cox proportional hazards model, not the parametric models, and is not designed for predictive modelers.
Background: As the aging issue and increased elderly esophageal cancer (EC) patients, we sought to study the clinical characteristics, treatment modality and outcomes of EC patients 70 years or older compared with those younger than 70 years old.. Methods: The national surveillance, epidemiology, and end results (SEER) database for the period from 1973 to 2013 was analyzed. The patient and treatment characteristics were compared between the age groups. Multivariate Cox proportional hazard regression analyses were also performed to identify independent prognostic factors. Propensity-score matching analyses (PSA) regarding survival after different treatments were also performed in locoregional EC.. Results: Compared with the younger group, patients 70 years or older were characterized by having a higher proportion of patients with female gender, white race, localized disease, non-adenocarcinoma and without any treatment, as well as inferior overall survival (OS) [hazard ratio (HR), 1.324] and ...
Background: Periodontal disease, a common disorder of the tissue surrounding and supporting the teeth, is a major cause of tooth loss in adults. Periodontal infection by oral microorganisms may have systemic effects and has been associated with several types of cancer. However, its association with liver cancer has only been examined in two prospective studies, both of which had very small number of liver cancer cases (n , 20).. Methods: We examined the association of tooth loss, as a proxy measure of periodontal infection, with primary liver cancer incidence and chronic liver disease mortality in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) study, a prospective cohort of male Finnish smokers (n = 29,096). Number of permanent teeth lost was assessed at study baseline (1985-1988). We used Cox proportional hazards models to calculate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). As a sensitivity analysis, we conducted a nested case-control study to ...
There is growing evidence linking time in range (TIR), an emerging metric for assessing glycemic control, to diabetes-related outcomes. We aimed to investigate the association between TIR and mortality in patients with type 2 diabetes.A total of 6,225 adult patients with type 2 diabetes were included from January 2005 to December 2015 from a single center in Shanghai, China. TIR was measured with continuous glucose monitoring at baseline, and the participants were stratified into four groups by TIR: ,85%, 71-85%, 51-70%, and ≤50%. Cox proportional hazards regression models were used to estimate the association between different levels of TIR and the risks of all-cause and cardiovascular disease (CVD) mortality.The mean age of the participants was 61.7 years at baseline. During a median follow-up of 6.9 years, 838 deaths were identified, 287 of which were due to CVD. The multivariable-adjusted hazard ratios associated with different levels of TIR (,85% [reference group], 71-85%, 51-70%, and ...
The profiles of patients with fulminant hepatic failure (FHF) from developing countries have not been reported earlier. The current study was conducted prospectively, at a single tertiary care center in India, to document the demographic and clinical characteristics, natural course, and causative profile of patients with FHF as well as to define simple prognostic markers in these patients. Four hundred twenty-three consecutive patients with FHF admitted from January 1987 to June 1993 were included in the study. Each patients serum was tested for various hepatotropic viruses. Univariate Coxs regression for 28 variables, multivariate Coxs proportional hazard regression, stepwise logistic regression, and Kaplan-Meier survival analysis were done to identify independent predictors of outcome at admission. All patients presented with encephalopathy within 4 weeks of onset of symptoms. Hepatotropic viruses were the likely cause in most of these patients. Hepatitis A (HAV), hepatitis B (HBV), ...
OBJECTIVE: Evaluate the incidence and predictors of HIV acquisition from outside partners in serodiscordant couples. METHODS: Demographic, behavioral, and clinical exposures were measured quarterly in a cohort of serodiscordant cohabiting couples in Zambia from 1995 to 2012 (n = 3049). Genetic analysis classified incident infections as those acquired from the study partner (linked) or acquired from an outside partner (unlinked). Factors associated with time to unlinked HIV infection were evaluated using multivariable Cox proportional hazards regression stratified by sex. RESULTS: There were 100 unlinked infections in couples followed for a median of 806 days. Forty-five infections occurred in women [1.85/100 couple-years; 95% confidence interval (CI): 1.35 to 2.47]. Risk of female unlinked infection (vs. nonseroconverting females) was associated with reporting being drunk weekly/daily vs. moderate/nondrinkers at baseline [adjusted hazard ratio (aHR) = 5.44; 95% CI: 1.03 to 28.73], genital ulcers ...
Methods This meta-analysis included data from individual patients with RA randomized to double-blind treatment with combination therapy of ADA+MTX vs. MTX monotherapy in Phase II/III clinical trials (ARMADA, DE019, PREMIER, and OPTIMA [first double-blind period]); the maximum double-blind trial duration was 2 years. All patients who received at least one dose of study drugs were included. The primary outcome was the time from baseline to a MACE, a composite of nonfatal myocardial infarction (MI), nonfatal stroke, and CV death. These component events were also studied separately. Events were adjudicated by a blinded external panel of 2 cardiologists and 1 neurologist. Times to events were compared between the ADA+MTX and MTX arms using Kaplan-Meier estimates of the cumulative risk and Cox proportional-hazards models stratified by trial. The sequential Holm procedure was used to account for testing of each MACE component. Multivariable Cox models were also applied, with stratification by trial and ...
Thirteen patients (7%) with SVR and 100 patients (30%) without SVR died after prolonged follow-up of our cohort, which was more than 4 times the number of deaths registered during the first data collection (n = 2 among patients with SVR and n = 24 among patients without SVR).11 There was a significant difference in the cumulative 10-year mortality rate between patients with SVR (8.9%; 95% CI, 3.3%-14.5%) and without SVR (26.0%; 95% CI, 20.2%-28.4%; P < .001) (Figure). Cox proportional hazards regression analysis showed that SVR was associated with a statistically significant reduction in the hazard of overall death (adjusted hazard ratio [HR], 0.26; 95% CI, 0.14-0.49; P < .001) (Table 3, model 1). Other baseline factors significantly associated with all-cause mortality in multivariate analysis were older age, HCV genotype 3 infection, higher Ishak fibrosis score, presence of diabetes, and a history of severe alcohol use. Patients with HCV genotype 3 infection were younger (median [IQR] age, 44 ...
Background NGR-hTNF (asn-gly-arg-human tumor necrosis factor) induces systemic release of cytokines and intratumoral infiltration of effector T cells. Intravenous infusion of NGR-hTNF is characterized by onset of IRR, mostly consisting of transient grade 1-2 chills. Incidence, predictors of development, and relationships with outcome of IRR were assessed across 5 phase 2 single-arm trials of NGR-hTNF.. Methods 205 patients (pts) with solid tumors received NGR-hTNF 0.8 µg/m2 every 3 weeks (q3w) given either alone in colon cancer (n = 45), liver cancer (n = 40), and mesothelioma (n = 55), or with doxorubicin in small-cell lung cancer (n = 28) and ovarian cancer (n = 37). Tumor assessment by RECIST was done q6w until progressive disease (PD). Logistic and Cox proportional-hazards regression models were used to analyze associations between IRR and outcome, in terms of response rate (RR, complete and partial response), disease control rate (DCR, rate of pts without PD at 6 weeks), and ...
Potential effect of various immunocompetent cells from ascitic fluid on overall survival calculated using Cox proportional-hazards regression model
在先前的三篇文章已經有介紹存活分析(Survival analysis)的使用時機、如何繪製存活曲線圖(Kaplan-Meier curve),以及如何比較「組別」之間的存活曲線是否有顯著差異(Log
From 1993 to 1997, 27?148 men and 29?863 women, aged 50 to 64 year, were recruited into the Danish prospective study Diet, Cancer and Health. During 11.9 years of follow-up we identified 2028 cases of incident MI (1487 men and 541 women). BMI, waist circumference (WC), hip circumference and BIA of body composition including body fat mass (BFM), body fat percentage and LBM were measured at baseline. We used Cox proportional hazard models with age as time axis and performed extensive control for confounding. Weight, BMI, classical estimates of abdominal obesity and BIA estimates of obesity showed significant positive associations with incident MI. However, BFM adjusted for WC showed no association. Low LBM was associated with a higher risk of incident MI in both genders, and high LBM was associated with a higher risk in men ...
Continuous data were presented as median and IQR and categorical data as counts and percentages.. Cox proportional hazard regression analysis was used to evaluate the effect of variables on the overall survival. We adjusted for established risk factors, cardiac status and renal function in a basic model, to account for potential confounding effects. The basic model was built from the variables age, gender, tumour entity (with n,5) and tumour stage, which were included as possible predictors in a stepwise forward Cox regression. The p value for entering the stepwise model was set to 0.05, and the p value for exclusion was set to 0.10. To assess the robustness of the basic model and to test against overfitting, an additional bootstrap procedure was performed, repeating the variable selection for each of a total of 500 samples using the same entering and exclusion criteria. The frequency of a variable entering the model was counted. Significant predictors of the stepwise Cox regression, which ...
Background: Adrenocortical carcinoma (ACC) is a rare malignancy with poor outcomes. Objectives: To analyze the clinicopathologic features, treatment patterns and outcomes of patients with ACC who received systemic therapy at our center. Patients and Methods: This was a retrospective study conducted in a tertiary cancer center in India. Patients aged 15 years and older who were diagnosed with ACC between January 2011 and December 2018 and received systemic therapy were included in this study. For tumor staging, the European Network for the Study of Adrenal Tumors (ENSAT) system was used. The outcomes were reported as progression-free survival (PFS) and overall survival (OS). All statistical calculations were performed using the SPSS statistical software for Windows version 20.0. Results: Out of the 106 patients with ACC, 54 who received systemic therapy were included in this study. The median age of the cohort was 43 years (range, 15-72); 32 (59.3%) were men. Five (9.2%) patients had ENSAT Stage ...
Purpose Biomarkers for early detection of disease progression in MBC are urgently needed. We explored on-treatment increase in ctDNA fraction as an early prognostic biomarker of subsequent disease progression. Methods Eighty four paired samples from 70 patients with MBC were analyzed for levels of ctDNA, CEA, and CA 15-3. Baseline specimens were collected at the time of initiation of a new line of therapy and on-treatment specimens were obtained 4-12 weeks later. Each patient underwent a CT scan of chest, abdomen and pelvis on 4-16 weeks (on average 7 weeks) later. Sequencing panel of 73 genes was used to quantify ctDNA. Genomic progression was predefined as an increase ≥25% in total MAF from baseline to on-treatment, in patients with MBC. Progression Free Survival (PFS) was estimated using univariate and multivariate Cox proportional hazards models, adjusting for tumor hormonal status, age at metastatic diagnosis, time elapsed and number of prior therapies received. Results Tumor-specific ...
Description: This course focuses on methods for analyzing time-to-event data. This course will explore non-parametric methods for analyzing time-to-event data like Life tables, the Kaplan-Meier method, the Nelson-Aalen method and the log-rank test. This course will also explore semi-parametric models such as the Cox proportional hazards regression models and parametric models inlcuding exponential, Weibull and log-logistic regression model ...
The nested case-control (NCC) design is widely used in epidemiologic studies as a cost-effective subcohort sampling method to study the association between a disease and its potential risk factors. NCC data are commonly analyzed using Thomas partial likelihood approach under the Cox proportional hazards model assumption. However, the linear modeling form in the Cox model may be insufficient for practical applications, especially when there are a large number of risk factors under investigation. In this paper, we consider a partially linear single index proportional hazards model, which includes a linear component for covariates of interest to yield easily interpretable results and a nonparametric single index component to adjust for multiple confounders effectively. We propose to approximate the nonparametric single index function by polynomial splines and estimate the parameters of interest using an iterative algorithm based on the partial likelihood. Asymptotic properties of the resulting ...
Supplementary MaterialsFigure S1: Immunological properties from the materials presented in desk S1. (1.2M) GUID:?47640B6B-0287-4C90-B672-118435E94B5F Amount S2: TNF- creation by individual macrophage-like THP-1 cells subsequent incubation with amphiphiles 1C21. TC supernatants had been supervised for cytokine creation via ELISA, and email address details are reported in pg/mL. All scholarly research were performed in two unbiased natural… Continue reading Supplementary MaterialsFigure S1: Immunological properties from the materials presented in desk. ...
Reliable biomarkers of apatinib response in gastric cancer (GC) are lacking. We investigated the association between early presence of common adverse events (AEs) and clinical outcomes in metastatic GC patients. We conducted a retrospective cohort study using data on 269 apatinib-treated GC patients in two clinical trials. AEs were assessed at baseline until 28 days after the last dose of apatinib. Clinical outcomes were compared between patients with and without hypertension (HTN), proteinuria, or hand and foot syndrome (HFS) in the first 4 weeks. Time-to-event variables were assessed using Kaplan-Meier methods and Cox proportional hazard regression models. Binary endpoints were assessed using logistic regression models. Landmark analyses were performed as sensitivity analyses. Predictive model was analyzed, and risk scores were calculated to predict overall survival. Presence of AEs in the first 4 weeks was associated with prolonged median overall survival (169 vs. 103 days, log-rank p = 0.0039;
Synonyms for Hazard function in Free Thesaurus. Antonyms for Hazard function. 108 synonyms for function: purpose, business, job, concern, use, part, office, charge, role, post, operation, situation, activity, exercise, responsibility.... What are synonyms for Hazard function?
Methods: A total of 737 patients with dilated cardiomyopathy clinically referred for CMR-based evaluation were prospectively enrolled in the Cardiovascular Imaging Registry of Calgary (CIROC) between January 2015 and June 2018. In addition to this referral status, the study population was required to have confirmation of LVEF≤50% by CMR, no known CAD, no prior MI, and no CMR evidence of either prior ischemic injury or acute myocarditis. All underwent routine collection of patient demographics, comorbidities and symptom scores and standardized reporting using commercial software (Acuity, Cohesic Inc) followed by automated linkage to administrative databases for the collection of laboratory, pharmacy and ICD-10 coded clinical outcome data. Patients were followed for the combined endpoint of heart failure hospital admission or death. A multivariable cox proportional hazards model was developed and was used to establish a points-based risk score for prediction of the primary outcome ...
6. Stats: More than 90% censored values (April 22, 2005). Someone asked me about running a Cox proportional hazards regression model when over 90% of the observations were censored. That means (if the outcome of interest was death), that your research subjects did not cooperate and die fast enough. Good news from the patients perspective, but bad news for the statistician. 90% censored observations is not a problem, though, as long as your sample size is adequate. As a rough rule of thumb, you need to have 25 to 50 events (uncensored observations) in each treatment group to have reasonable precision. Of course, if you have fewer events, the model is still valid, but your confidence intervals may end up being wider than youd really like.. 5. Stats: Stratified Cox regression models (March 22, 2005). Someone sent me an email asking about a Cox regression model that included a strata for clinics. Whats the best way to handle strata? Thats a tricky question to answer. The first question you might ...
Cancer, Breast, Breast Cancer, Mortality, Recurrence, Risk, Diagnosis, Women, Association, Survivors, Survival, Associations, Cox Proportional Hazards Models, Hazards Models, Prognosis, Proportional Hazards Models, Health, Confidence Intervals, Recurrences, Physical Activity
Create the simplest test data set # test1 ,- list(time= c(4, 3,1,1,2,2,3), status=c(1,NA,1,0,1,1,0), x= c(0, 2,1,1,1,0,0), sex= c(0, 0,0,0,1,1,1)) coxph( Surv(time, status) ~ x + strata(sex), test1) #stratified model # # Create a simple data set for a time-dependent model # test2 ,- list(start=c(1, 2, 5, 2, 1, 7, 3, 4, 8, 8), stop =c(2, 3, 6, 7, 8, 9, 9, 9,14,17), event=c(1, 1, 1, 1, 1, 1, 1, 0, 0, 0), x =c(1, 0, 0, 1, 0, 1, 1, 1, 0, 0) ) summary( coxph( Surv(start, stop, event) ~ x, test2 ...
By adapting survival analysis on the staying at home of qualified recipients for long-term care, this paper attempts to empirically clarify what factors contribute to staying at home as long as possible. Using the National Health Insurance Services Long-Term Care Qualification Longitudinal Survey (2008-2015), this paper analyzed the factors contributing to the initial benefit selection and at-home survival rate. The results of the factor analysis showed that the probability of choosing home care was higher for males, lower age group, having family caregivers. On the other hand, in the case of dementia, the probability of choosing institutional care was high. As a result of the life table analysis, it was found that 13.1% of the initial home care users changed to institutional care, and about 71% of the moves take place between 2 and 4 years. The Cox proportional hazards regression model analysis showed that the likelihood of withdrawal from home care was higher: for women, for older, for those ...
By adapting survival analysis on the staying at home of qualified recipients for long-term care, this paper attempts to empirically clarify what factors contribute to staying at home as long as possible. Using the National Health Insurance Services Long-Term Care Qualification Longitudinal Survey (2008-2015), this paper analyzed the factors contributing to the initial benefit selection and at-home survival rate. The results of the factor analysis showed that the probability of choosing home care was higher for males, lower age group, having family caregivers. On the other hand, in the case of dementia, the probability of choosing institutional care was high. As a result of the life table analysis, it was found that 13.1% of the initial home care users changed to institutional care, and about 71% of the moves take place between 2 and 4 years. The Cox proportional hazards regression model analysis showed that the likelihood of withdrawal from home care was higher: for women, for older, for those ...
Two methods are given for the joint estimation of parameters in models for competing risks in survival analysis. In both cases Coxs proportional hazards regression model is fitted using a data duplication method. In principle either method can be used for any number of different failure types, assu …
IMPORTANCE The association between early exposure to animals and type 1 diabetes in childhood is not clear. OBJECTIVE To determine whether exposure to dogs during the first year of life is associated with the development of type 1 diabetes in childhood. DESIGN, SETTING, AND PARTICIPANTS A nationwide cohort study utilizing high-quality Swedish national demographic and health registers was conducted. A total of 840 593 children born in Sweden from January 1, 2001, to December 31, 2010, were evaluated. Type 1 diabetes was identified using diagnosis codes from hospitals and dispensed prescriptions of insulin. Cox proportional hazards regression models were used to assess the association between exposure to dogs and risk of type 1 diabetes in childhood. The possible association was further investigated by performing dose-response and breed group-specific analyses. The cohort was followed up until September 30, 2012. Data analysis was conducted from October 15, 2015, to February 8, 2017. EXPOSURES ...
A new study isuggests that people with atrial fibrillation who exercise have a reduced risk for cardiovascular disease and all-cause mortality.
In survival data analysis, the aim of fitting a Coxs proportional hazards (Coxs PH) model is to estimate the effect of covariates on the baseline hazard function. However, Coxs PH model makes a number of assumptions, which may be violated in many applications. Applying Coxs PH model without ensuring that its underlying assumptions are validated can lead to negative consequences on the resulting estimates. In this article, a generalization of the Coxs PH model in terms of the increment in cumulative hazard function taking a form similar to the Coxs PH model, with the extension that the increment in baseline cumulative hazard function is raised to a power function. The problem of parameter estimation for the parameters in that generalization of Coxs PH model will be solved using Bayesian inference. When the increment in cumulative hazard function is a gamma process, the likelihood has a semi-closed form, which allows posterior sampling to be carried out for the parameters, hence achieving ...
LB-371 The relationship between socioeconomic status (SES) and health has long been of interest to epidemiologists and social policy makers. We prospectively examined the association between SES and the risk of developing first primary cancers in the NIH-AARP Study, a cohort of 498,447 50-71 year olds without cancer at enrollment in 1995/96. We used highest attained education, reported at baseline, as a proxy for SES. During 5 years of follow-up, 34,955 cancers were identified in 8 state cancer registries. Cox proportional hazards models were utilized to estimate relative risks (RR) and 95% confidence intervals (95%CI) for subjects who did not complete high school compared to those with post-graduate education, stratified by sex. In age adjusted models, men with lower educational attainment had significantly increased risks of developing cancers of the lung (RR:4.27; 95% CI:3.64-5.00), head and neck (RR:1.88; 95%CI:1.38-2.58), esophagus (RR:3.34; 95% CI:2.13-5.23), stomach (RR:2.60; ...
We discuss causal mediation analyses for survival data and propose a new approach based on the additive hazards model. The emphasis is on a dynamic point of view, that is, understanding how the direct and indirect effects develop over time. Hence, importantly, we allow for a time varying mediator. To define direct and indirect effects in such a longitudinal survival setting we take an interventional approach (Didelez, 2018) where treatment is separated into one aspect affecting the mediator and a different aspect affecting survival. In general, this leads to a version of the nonparametric g-formula (Robins, 1986). In the present paper, we demonstrate that combining the g-formula with the additive hazards model and a sequential linear model for the mediator process results in simple and interpretable expressions for direct and indirect effects in terms of relative survival as well as cumulative hazards. Our results generalize and formalize the method of dynamic path analysis (Fosen, Ferkingstad, Borgan,
The findings also suggest that regardless of a persons level of fat mass, a higher level of muscle mass helps reduce the risk of death.
where X1, X2,...,Xp denote a set of p explanatory variables that help to form this hazard rate at time t.. The coefficients, βk1,βk2,...,βkp for k=1,2,... can be estimated using a maximum likelihood methodology. The results obtained can be interpreted in much the same way as the results for a Cox proportional hazards model. More specifically, a positive valued estimate for βkj would suggest that an increase in the value of the variable j increases the hazard rate associated with the occurrence of the cause specific outcome k (i.e. shortens the length of time until the event occurs). Similarly, a negative valued estimate for βkj would suggest that an increase in the value of variable j decreases the hazard rate associated with the occurrence of the cause specific outcome k (i.e. lengthens the time until occurrence of the event). The fitted model results along with their p-values are presented in Table 2. For all analyses, SAS software was used; p≤0.05 was considered statistically ...
Type 2 diabetes is increasing globally and in Asia. The purpose of this study was to examine the association of a fit-fat index (FFI) with diabetes incidence among Japanese men. In total 5,014 men aged 18-64 years old, who had an annual health check up with no history of major chronic disease at baseline from 2002 to 2009 were observed. CRF was estimated via cycle ergometry. Overall, 7.6% of the men developed diabetes. The mean follow-up period was 5.3 years. Hazard ratios, 95% confidence intervals and P trend for diabetes incidence were obtained using the Cox proportional hazards model while adjusting for confounding variables ...
Type 2 diabetes is increasing globally and in Asia. The purpose of this study was to examine the association of a fit-fat index (FFI) with diabetes incidence among Japanese men. In total 5,014 men aged 18-64 years old, who had an annual health check up with no history of major chronic disease at baseline from 2002 to 2009 were observed. CRF was estimated via cycle ergometry. Overall, 7.6% of the men developed diabetes. The mean follow-up period was 5.3 years. Hazard ratios, 95% confidence intervals and P trend for diabetes incidence were obtained using the Cox proportional hazards model while adjusting for confounding variables ...
The paper, titled Proportional hazards models based on biased samples and estimated selection probabilities, was published in Vol. 36, No. 1, 2008, pp. 111-127.. Unrepresentative samples are common in observational studies and often lead to biased parameter estimates. The authors propose a two-stage inverse-probability-of-selection weighted proportional hazards model, using weights estimated from auxiliary information on the sampling process. The estimation of the weights is explicitly incorporated into the inference procedures, which leads to gains in efficiency relative to existing methods that treat the weights as fixed. The method is widely applicable from epidemiologic to ecological studies. Through the proposed methods, Pan and Schaubel demonstrate that the increased failure risk associated with expanded criteria on donor kidneys is greatly underestimated by previous analyses which did not account for the inherent bias introduced by the acceptance/discard process.. Dr. Pan is an ...
Methods: A cohort of 517,996 Korean adults, who did not have liver cancer at baseline and attended a health screening including free thyroxine (FT4) and TSH, were followed for up to 16 years. High and low TSH and FT4 were defined as those above the upper bound of reference interval and those below the lower bound of reference interval of their corresponding reference intervals, respectively. Mortality information was ascertained through National Death Records. The adjusted HR (aHR) with 95% confidence interval (CI) were estimated using a Cox proportional hazard model. ...
The goal of this project is to develop an interactive, Web-based Prognostigram program for adult patients with newly diagnosed cancer. The prognostic program creates individualized survival curves based on the Cox Proportional Hazards model of survival data from Barnes-Jewish Hospital (BJH) Oncology Data Services (ODS) and SEER*Stat (National Cancer Institute, Surveillance, Epidemiology, and End Results Software package). This program also includes important comorbid health information. Patient and physician focus groups were held to explore the utility of the program. Overall, both groups felt the program was informative and easy to use. Specific suggestions for improvement were made ... Read the full Final Report.. ...
In a standard Cox model you assume that all subjects share the same hazard (which can vary as a function of time) except for a (multiplicative) effect of their covariates. This is the proportional hazard assumption,. $\lambda(t\mid X) = \lambda_0(t)\exp(X^T\beta),$. where $\lambda(t\mid X)$ is the hazard function for a subject with covariates $X$.. In a stratified model, you allow the baseline hazard to vary between strata, just like it would if you fitted separate models, but you restrict the effect of the covariates to be the same for each strata. For each subject in strata $i$, you have. $\lambda_i(t\mid X) = \lambda_{0i}(t)\exp(X^T\beta).$. Note that there is no $i$ on the $\beta$ vector. If you fit separate models for each straum, you would have. $\lambda_i(t\mid X) = \lambda_{0i}(t)\exp(X^T\beta_i),$. which is the most general model (of these three models).. ...
CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): Likelihood based regression models, such as the normal linear regression model and the linear logistic model, assume a linear (or some other parametric) form for the covariate effects. We introduce the Local Scotinq procedure which replaces the liner form C Xjpj by a sum of smooth functions C Sj(Xj)a The Sj(.) s are unspecified functions that are estimated using scatterplot smoothers. The technique is applicable to any likelihood-based regression model: the class of Generalized Linear Models contains many of these. In this class, the Locul Scoring procedure replaces the linear predictor VI = C [email protected] by the additive predictor C ai ( hence, the name Generalized Additive Modeb. Local Scoring can also be applied to non-standard models like Coxs proportional hazards model for survival data. In a number of real data examples, the Local Scoring procedure proves to be useful in uncovering non-linear covariate effects. It has the
Results Three Cox proportional hazards models for prediction of 10-year recurrent vascular event risk were developed based on age and sex in addition to clinical parameters (model A), carotid ultrasound findings (model B) or both (model C). Clinical parameters were medical history, current smoking, systolic blood pressure and laboratory biomarkers. In a separate part of the dataset, the concordance statistic of model A was 0.68 (95% CI 0.64 to 0.71), compared to 0.64 (0.61 to 0.68) for model B and 0.68 (0.65 to 0.72) for model C. Goodness-of-fit and calibration of model A were adequate, also in separate subgroups of patients having coronary, cerebrovascular, peripheral artery or aneurysmal disease. Model A predicted ,20% risk in 59% of patients, 20-30% risk in 19% and ,30% risk in 23%.. ...
get file =C:Dataasa2gbcs.sav. compute hormonexnodes = (hormone-1)*nodes. exe. coxreg rectime with nodes hormone hormonexnodes /status=censrec(1) /method = enter hormone nodes hormonexnodes /print = corr. data list free /nodes. begin data 0 1 3 5 7 9 10 15 20 25 30 35 40 45 50 end data. *Creating the variance and covariance matrix. compute #vn = .008**2. compute #vh = .164**2. compute #vhxn = .015**2. compute #cov_n_h = .291*sqrt((#vn)*(#vh)). compute #cov_n_hxn =-.529*sqrt((#vn)*(#vhxn)). compute #cov_h_hxn =-.643*sqrt((#vh)*(#vhxn)). compute log_hr = -.606 + nodes*(.038). compute se = sqrt(#vh + nodes**2*(#vhxn) + 2*nodes*#cov_h_hxn). compute log_hr_l = log_hr - 1.96*se. compute log_hr_u = log_hr + 1.96*se. exe. graph /scatterplot(overlay) = nodes nodes nodes with log_hr log_hr_l log_hr_u (pair). ...
Concepts, models and techniques in survival analysis including types of censoring and truncation, Kaplan-Meier estimators, log-rank statistics, parametric models, proportional hazards models, extended PH models, competing risks, recurrent events and frailty models ...
proportional hazard model. *prospect theory. *protoindustrialization. *psychological games. *psychology of social networks ... The New Palgrave: Dictionary of Economics, Volume 7 real balances - stochastic volatility models ...
... and for some non-linear regression models. Other non-linear models, such as proportional hazards models for survival analysis, ... Hughes, M. D. (1993). "Regression dilution in the proportional hazards model". Biometrics. 49: 1056-1066. doi:10.2307/2532247. ... The case that x is fixed, but measured with noise, is known as the functional model or functional relationship. See, for ... Carroll, R. J., Ruppert, D., and Stefanski, L. A. (1995). Measurement error in non-linear models. New York, Wiley. Riggs, D. S ...
The Cox model assumes that the hazards are proportional. The proportional hazard assumption may be tested using the R function ... For quantitative predictor variables, an alternative method is Cox proportional hazards regression analysis. Cox PH models work ... Cox models may be extended for such time-varying covariates. The Cox PH regression model is a linear model. It is similar to ... Tree-structured survival models may give more accurate predictions than Cox models. Examining both types of models for a given ...
"On the Use of the Accelerated Failure Time Model as an Alternative to the Proportional Hazards Model in the Treatment of Time ... Patel, K; Kay, R; Rowell, L (2006). "Comparing proportional hazards and accelerated failure time models: an application in ... Simino, J.; Hollander, M.; McGee, D. (2012). "Calibration of Proportional Hazards and Accelerated Failure Time Models". ... In most toxicological models, the effect is proportional to concentration of toxin or amount of insult. However, in the AFT ...
Van Den Poel; Lariviére (2004). "Customer Attrition Analysis For Financial Services Using Proportional Hazard Models". European ... Several studies combine several different types of predictors to develop a churn model. This model can take demographic ... Since these models generate a small prioritized list of potential defectors, they are effective at focusing customer retention ... One of the main objectives of modeling customer churn is to determine the causal factors, so that the company can try to ...
"Customer attrition analysis for financial services using proportional hazard models". European Journal of Operational Research ... A principal danger of such data redundancy is that of overfitting in regression analysis models. The best regression models are ... Such a model is often called "low noise" and will be statistically robust (that is, it will predict reliably across numerous ... More importantly, the usual use of regression is to take coefficients from the model and then apply them to other data. Since ...
Survival analysis includes Cox regression (Proportional hazards model) and Kaplan-Meier survival analysis. Procedures for ...
An Analysis Based on the Proportional Hazards Model."Journal of Animal Ecology , Vol. 54, No. 3 (Oct., 1985). ...
"Methods for the Analysis of Sampled Cohort Data in the Cox Proportional Hazards Model" (PDF). Annals of Statistics. 23 (5): ... The analysis of a nested case-control model must take into account the way in which controls are sampled from the cohort. ... Since the covariate is not measured for all participants, the nested case-control model is both less expensive than a full ...
... parametric survival models and the Cox proportional hazards model may be useful to estimate covariate-adjusted survival. The ... Both are based on rewriting the survival function in terms of what is sometimes called hazard, or mortality rates. However, ... Kaplan-Meier estimator can be derived from maximum likelihood estimation of hazard function. More specifically given d i {\ ... "sts - Generate, graph, list, and test the survivor and cumulative hazard functions" (PDF). Stata Manual. Cleves, Mario (2008). ...
These estimators range from fully parametric models such as the Mixed Proportional Hazard model, to nonparametric and ... Salant shows that heterogeneity in hazard rates between the stock and the flow distribution provides a key to understanding why ... Hausman, J. A. and T. Woutersen (2014), Estimating a semi-parametric duration model without specifying heterogeneity. Journal ...
The logrank statistic can be derived as the score test for the Cox proportional hazards model comparing two groups. It is ... assume the hazard functions in the two groups are proportional with hazard ratio λ {\displaystyle \lambda } and d 1 {\ ... If the hazard ratio is λ {\displaystyle \lambda } , there are n {\displaystyle n} total subjects, d {\displaystyle d} is the ... The logrank test statistic compares estimates of the hazard functions of the two groups at each observed event time. It is ...
Meller Grambsch is an American biostatistician known for her work on survival models including proportional hazards models. She ... With Terry M. Therneau, Grambsch is the author of the book Modeling Survival Data: Extending the Cox Model (Statistics for ... Reviews of Modeling Survival Data: Broström, Göran, zbMATH, Zbl 0958.62094CS1 maint: untitled periodical (link) Borgan, Ørnulf ...
The proportional hazards model, which is widely used in the analysis of survival data.[4] An example is survival times in ... Cox proportional hazards model. Stochastic processes. Design of experiments. Analysis of binary data. ... "the development of the Proportional Hazard Regression Model." In 2010 he was awarded the Copley Medal of the Royal Society "for ... Time series models in econometrics, finance and others (Chapman & Hall/CRC, 1996). With D. V. Hinkley and Ole E. Barndorff- ...
The proportional hazards model, which is widely used in the analysis of survival data, was developed by him in 1972. An example ... "the development of the Proportional Hazard Regression Model." In 2010 he was awarded the Copley Medal of the Royal Society "for ... Time series models in econometrics, finance and others (Chapman & Hall/CRC, 1996). With D. V. Hinkley and Ole E. Barndorff- ... Cox, David R (1972). "Regression Models and Life-Tables". Journal of the Royal Statistical Society, Series B. 34 (2): 187-220. ...
... creates proportional hazards models, one class of survival analysis: see proportional hazards models for ... Other generalized linear models such as the negative binomial model or zero-inflated model may function better in these cases. ... A Poisson regression model is sometimes known as a log-linear model, especially when used to model contingency tables. Negative ... This model is popular because it models the Poisson heterogeneity with a gamma distribution. Poisson regression models are ...
Kaplan-Meier estimators and Cox proportional hazards models for time to coronary heart disease after receipt of hormone ... Vonesh, Edward F.; Chinchilli, Vernon G. (1997). "Crossover Experiments". Linear and Nonlinear Models for the Analysis of ...
Her work in this time on the graft-versus-tumor effect become "the first major application of the proportional hazards model ... for serving as a role model and mentor for graduate students and young faculty; for her scholarship in teaching and research, ...
... mathematical statistician whose research topics include missing data in longitudinal studies and proportional hazards models. ... "Role models needed for women students, says new prof", Update!, St. Jerome's College, vol. 5 no. 2, p. 7, Fall 1985, retrieved ...
... proportional hazards models, and M-estimators. Given the objective function 1 N ∑ i = 1 N f ( x i , y i , α , β ) {\ ... proportional hazards models, and M-estimators. Lasso's ability to perform subset selection relies on the form of the constraint ... lasso regularization is easily extended to other statistical models including generalized linear models, generalized estimating ... This can be modeled using the following regularization: ∑ i < j p , β i − β j , ≤ t 2 . {\displaystyle \sum _{i. < p < 1 {\ ...
A proportional hazards regression model was used for each cancer type with the cancer as the outcome and PFOA serum level ... Office of Environmental Health Hazard Assessment, Cancer Toxicology and Epidemiology Section, Reproductive and Cancer Hazard ... Models were adjusted for time-varying- smoking and alcohol consumption, as well as sex, education and 5-year birth cohort. The ... hazard ratio = 1.10 and 1.34, respectively, for a 1-unit increase in log-transformed serum PFOA]. The study consisted of 32,254 ...
An Analysis Based on the Proportional Hazards Model." Journal of Animal Ecology. 54 (3). Coombs, E. M., et al., Eds. (2004). ...
An Analysis Based on the Proportional Hazards Model."Journal of Animal Ecology, Vol. 54, No. 3 (Oct., 1985). Helantera, Heikki ... F. polyctena is consistent with this model, with almost completely sterile workers that do not lay eggs. This is in contrast to ... Aubert and Richard proposed this social vaccination model, where they argue that if fellow nestmates groom an infected ant, ...
Propensity probability Propensity score Propensity score matching Proper linear model Proportional hazards models Proportional ... model Hierarchical Bayes model Hierarchical clustering Hierarchical hidden Markov model Hierarchical linear modeling High- ... model) - a time series model Sethi model Seven-number summary Sexual dimorphism measures Shannon-Hartley theorem Shape of the ... latent variable model Latent class model Latent Dirichlet allocation Latent growth modeling Latent semantic analysis Latin ...
It is a key component of the proportional hazards model: using a restriction on the hazard function, the likelihood does not ... of a model, given an event, is the negative of the surprisal of the event, given the model: a model is supported by an event to ... Instead, what is used is the relative likelihood of models (see below). The likelihood ratio of two models, given the same ... one compares models (parameters), holding data fixed; while in odds, one compares events (outcomes, data), holding the model ...
... proportional hazard models). The compensation law of mortality also represents a great challenge for many theories of aging and ... PMID 111909 Gavrilov, L.A. "A mathematical model of the aging of animals". Doklady Akademii Nauk SSSR, 1978, 238(2): 490-492. ...
... as reverse-engineered by ProPublica using logistic regression and Cox's proportional hazard model. Hastie, T. J.; Tibshirani, R ... is estimated using a generalized linear model: E ⁡ ( Y , X ) = P ( Y = 1 , X ) = g − 1 ( X β ) {\displaystyle {\begin{aligned}\ ... J. (1990). Generalized Additive Models. Chapman & Hall/CRC. ISBN 978-0-412-34390-2. Toren, Yizhar (2011). "Ordinal Risk-Group ...
For logistic regression or Cox proportional hazards models, there are a variety of rules of thumb (e.g. 5-9, 10 and 10-15 - the ... The book Model Selection and Model Averaging (2008) puts it this way. Given a data set, you can fit thousands of models at the ... An under-fitted model is a model where some parameters or terms that would appear in a correctly specified model are missing. ... Model Selection and Model Averaging, Cambridge University Press. Harrell, F. E., Jr. (2001), Regression Modeling Strategies, ...
... in particular proportional hazards models in survival analysis and logistic regression) while keeping the risk of overfitting ... "Chapter 8: Statistical Models for Prognostication: Problems with Regression Models". Archived from the original on October 31, ... Harrell, F. E. Jr.; Lee, K. L.; Mark, D. B. (1996). "Multivariable prognostic models: issues in developing models, evaluating ... Alternatively, three requirements for prediction model estimation have been suggested: the model should have a global shrinkage ...
... oxide capacitance in MOSFET devices Cox model, a proportional hazards model in statistics Cox model engines, made by L.M. Cox ... an Atlanta-based business unit of Cox Enterprises Cox Models, aka Cox Hobbies Cox Sports, a regional sports network that served ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... Rasch, G. (1960). Probabilistic models for some intelligence and attainment tests. Copenhagen: Danish Institute for Educational ... Further progress was made by Georg Rasch (1960), who developed the probabilistic Rasch model that provides a theoretical basis ... For example, applications of measurement models in educational contexts often indicate that total scores have a fairly linear ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ...
It assumes a desire to develop along the traditional Western model of economic development which a few countries, such as Cuba ... They conclude that the percentage of the schooled population is proportional to the economic growth rate and inversely ... Rapid environmental and health hazards.. *Traffic fatalities and air pollution.. *Non communicable diseases. ... It assumes a desire to "develop" along the traditional Western model of economic development, which a few countries, such as ...
With sufficient power this could be a hazard to people near the cable. A properly placed and properly sized balun can prevent ... The outer diameter is roughly inversely proportional to the cutoff frequency. A propagating surface-wave mode that does not ... Coaxial cable is a particular kind of transmission line, so the circuit models developed for general transmission lines are ... with the depth of penetration being proportional to the square root of the resistivity. This means that, in a shield of finite ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ...
Space-filling model of ethyl stearate, or stearic acid ethyl ester, an ethyl ester produced from soybean or canola oil and ... This was attributed to the faster pressure drop at the edge of the spray pattern; there was a proportional relationship between ... Hazard. Mater. 107: 11-25. doi:10.1016/j.jhazmat.2003.11.013.. ... Space-filling model of methyl linoleate, or linoleic acid ... Rudolf Diesel's prime model, a single 10 ft (3.0 m) iron cylinder with a flywheel at its base, ran on its own power for the ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... The cache language models and other statistical language models used in natural language processing to assign probabilities to ... Such quantities can be modeled using a mixture distribution. Related to real-valued quantities that grow linearly (e.g. errors ... Well-known discrete probability distributions used in statistical modeling include the Poisson distribution, the Bernoulli ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... This can be done for instance using test-retest,[19] quasi-simplex,[20] or mutlitrait-multimethod models.[21] ... A user-centric model of voting intention from social media. Proceedings of the 51st Annual Meeting of the Association for ... Another source of error stems from faulty demographic models by pollsters who weigh their samples by particular variables such ...
In a sea state, the average(mean) energy density per unit area of gravity waves on the water surface is proportional to the ... and may represent hazards to safe navigation.[33] Waves generate about 2,700 gigawatts of power. Of those 2,700 gigawatts, only ... General circulation model. *Geostrophic current. *Global Ocean Data Analysis Project. *Gulf Stream ... The above formula states that wave power is proportional to the wave energy period and to the square of the wave height. When ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... for testing whether there is evidence of the need to move from a simple model to a more complicated one (where the simple model ... In order to model the observations regardless of being normal or skewed, Pearson, in a series of articles published from 1893 ... the Pearson distribution to model the observation and performing the test of goodness of fit to determine how well the model ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... More advanced statistical modeling can be used to adapt the inference to the sampling method. ...
More critical or optimized designs now routinely use mathematical modeling on a computer using software such as Radiance which ... Generally speaking, the energy expended is proportional to the design illumination level. For example, a lighting level of 400 ... however they contain mercury which is a disposal hazard. Due to the ability to reduce electricity consumption, many ... a standardized model of human visual brightness perception. In English, "lux" is used in both singular and plural.[27] ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... Suppose one is fitting the model Y. =. α. +. β. x. +. ε. {\displaystyle Y=\alpha +\beta x+\varepsilon }. where x is known, α ...
This is not considered to be a hazard for dust clouds.. *Propagating brush discharge is high in energy and dangerous. Occurs ... For modelling the effect of static discharge on sensitive electronic devices, a human being is represented as a capacitor of ... and can be roughly proportional to particulate flow.[11] Dust clouds of finely powdered substances can become combustible or ... Carlos Hernando Díaz, Sung-Mo Kang, Charvaka Duvvury, Modeling of electrical overstress in integrated circuits Springer, 1995 ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... Assessment of model and model fit[edit]. Having estimated a model, analysts will want to interpret the model. Estimated paths ... Model specification[edit]. Two main components of models are distinguished in SEM: the structural model showing potential ... Structural equation modeling (SEM) is a form of causal modeling that includes a diverse set of mathematical models, computer ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... Structural breaks in cointegration models[edit]. For a cointegration model, the Gregory-Hansen test (1996) can be used for one ... Structural changes and model stability in panel data are of general concern in empirical economics and finance research. Model ... For linear regression models, the Chow test is often used to test for a single break in mean at a known time period K for K ∈ [ ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... Some discussion of experimental design in the context of system identification (model building for static or dynamic models) is ... In the most basic model, cause (X) leads to effect (Y). But there could be a third variable (Z) that influences (Y), and X ... Charles S. Peirce also contributed the first English-language publication on an optimal design for regression models in 1876.[6 ...
These ideas are combined to form the linear no-threshold model which says that there is not a threshold at which there is an ... The occupational hazards from airborne radioactive particles in nuclear and radio-chemical applications are greatly reduced by ... and to a first approximation is proportional to the total mass of material per unit area interposed along the line of sight ... This most often creates a secondary radiation hazard, as the absorbing nuclei transmute to the next-heavier isotope, many of ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ...
Hazard, Samuel (1873). Santo Domingo, Past And Present; With A Glance At Haytl. p. 249.. ... The Dominican Republic's first Constitution was adopted on November 6, 1844, and was modeled after the United States ... A proportional representation of the Dominican Republic's exports. The Dominican Republic is the largest economy[24] (according ... Schools are based on a Spanish educational model; English and French are mandatory foreign languages in both private and public ...
It is also inversely proportional to the length of the cantilever. The relative popularity of the beam-deflection method can be ... Thomas, G.; Y. Ouabbas; P. Grosseau; M. Baron; A. Chamayou; L. Galet (2009). "Modeling the mean interaction forces between ... "Drug Delivery and Nanoparticles: Applications and Hazards". International Journal of Nanomedicine. 3 (2): 133-149. doi:10.2147 ... The 'optical leverage' (output signal of the detector divided by deflection of the cantilever) is inversely proportional to the ...
Likewise, the momentum p of a photon is also proportional to its frequency and inversely proportional to its wavelength: p. =. ... Particle model and quantum theory[edit]. See also: Quantization (physics) and Quantum optics ... and can be a health hazard. ... Wave model[edit]. Representation of the electric field vector ... They have a special restricted orientation and proportional magnitudes, E. 0. =. c. 0. B. 0. {\displaystyle E_{0}=c_{0}B_{0}}. ...
Argentina, which had been considered by the IMF to be a model country in its compliance to policy proposals by the Bretton ... The clout of member states is roughly proportional to its contribution to IMF finances. The United States has the greatest ... The incentive problem of moral hazard-when economic agents maximise their own utility to the detriment of others because they ...
Tleis, Nasser (2008), Power System Modelling and Fault Analysis, Elsevier, pp. 552-54, ISBN 978-0-7506-8074-5. ... Ohm's law is a basic law of circuit theory, stating that the current passing through a resistance is directly proportional to ... replacing the naked flames of gas lighting greatly reduced fire hazards within homes and factories.[73] Public utilities were ... The induced voltage is proportional to the time rate of change of the current. The constant of proportionality is termed the ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... A statistical model can be used or not, but primarily EDA is for seeing what the data can tell us beyond the formal modeling or ... Early statistical models were almost always from the class of linear models, but powerful computers, coupled with suitable ... Machine learning models are statistical and probabilistic models that capture patterns in the data through use of computational ...
Thoracic Model Analysis Using Finite Element Modeling and Vibration Table Testing Dr. Peter Matic, Dr. Alan Leung and Mr. Kirth ... Using gravitational force, the height of the drop mass above the vest was proportional to the impact energy. This test ... where the hazards to people and critical structures cannot be lessened by using wheeled robots or other techniques. ... In the early stages of World War II, the United States also designed body armor for infantrymen, but most models were too heavy ...
Photon energy is directly proportional to the wave frequency, so gamma ray photons have the highest energy (around a billion ... making them a health hazard. UV can also cause many substances to glow with visible light; this is called fluorescence. ... Wavelength is inversely proportional to the wave frequency,[5] so gamma rays have very short wavelengths that are fractions of ...
Proportional hazards models. *Accelerated failure time (AFT) model. *First hitting time. Hazard function. *Nelson-Aalen ... whereas a multiplicative model would be y. t. =. T. t. ×. C. t. ×. S. t. ×. I. t. .. {\displaystyle y_{t}=T_{t}\times C_{t}\ ... Enders, Walter (2004). "Models with Trend". Applied Econometric Time Series (Second ed.). New York: Wiley. pp. 156-238. ISBN 0- ... An additive model would be used when the variations around the trend do not vary with the level of the time series whereas a ...
A person's increased risk of contracting disease is directly proportional to the length of time that a person continues to ... Shihadeh A, Azar S, Antonios C, Haddad A (September 2004). "Towards a topographical model of narghile water-pipe café smoking: ... but having then suppressed the findings or formatted them to imply lessened or no hazard.[237] ...
The Cox Proportional Hazard Model on Fire. April 12, 2012 7:45 PM Subscribe. The Hunger Games Survival Analysis is kinda neat, ... To actually run the model, you will need to enter the data into a hazard model regression calculator, which can be found online ...
The generic term parametric proportional hazards models can be used to describe proportional hazards models in which the hazard ... Proportional hazards models are a class of survival models in statistics. Survival models relate the time that passes, before ... For example, assuming the hazard function to be the Weibull hazard function gives the Weibull proportional hazards model. ... hazards models and Poisson regression models which is sometimes used to fit approximate proportional hazards models in software ...
... From. Magdalena Kapelko ,[email protected],. To. ... st: proportional hazard assumption in parametric survival models. Date. Tue, 7 Jun 2011 01:49:22 +0200. Hi, I am analyzing the ... How to test if proportional hazard assumption holds in parametric survival models that assume Weibull or exponential ... influence of some variables on the probability of failure in the sample of firms using parametric survival model in STATA. ...
Proportional hazards models assume that the relative risk remains constant over time.[2] The Cox proportional hazard model is ... an example of a proportional hazards model. References. *↑ Anonymous (2019), Proportional hazards model (English). Medical ... In statistics and regression analysis, proportional hazards models are "statistical models used in survival analysis that ... Retrieved from "" ...
... heart modelling, cardiovascular and lung dynamics, neurobiology, computational neuroscience, biomechanics, biomedical ... H. H. Zhang and W. Lu, "Adaptive Lasso for Coxs proportional hazards model," Biometrika, vol. 94, no. 3, pp. 691-703, 2007. ... I. Sohn, J. Kim, S.-H. Jung, and C. Park, "Gradient lasso for Cox proportional hazards model," Bioinformatics, vol. 25, no. 14 ... Novel Harmonic Regularization Approach for Variable Selection in Coxs Proportional Hazards Model. Ge-Jin Chu, Yong Liang, and ...
The course focuses on the Cox proportional hazards model, not the parametric models, and is not designed for predictive ... fit the proportional hazards model *assess the fit of the model *fit Cox proportional hazards models for repeated events and ... introduction to the Cox proportional hazards model *model assessment*models with nonproportional hazards * model building and ... The course focuses on the Cox proportional hazards model, not the parametric models, and is not designed for predictive ...
"Proportional Hazards Models" by people in Harvard Catalyst Profiles by year, and whether "Proportional Hazards Models" was a ... "Proportional Hazards Models" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH ( ... Proportional Hazards Models*Proportional Hazards Models. *Proportional Hazard Models. *Hazard Model, Proportional ... Below are the most recent publications written about "Proportional Hazards Models" by people in Profiles. ...
Quantify Relative Risk Using a Cox-Proportional Hazards Model Compare survival rates for different stages of cancer of the ...
We develop methods for comparative APC analysis of two independent cause-specific hazard rates assuming that an APC model holds ... analysis is widely used in cancer epidemiology to model trends in cancer rates. ... When a given proportional hazards model appears adequate, we derive simple expressions for the relative hazards using ... Proportional hazards models and age-period-cohort analysis of cancer rates Stat Med. 2010 May 20;29(11):1228-38. doi: 10.1002/ ...
Fit Proportional Hazards Regression Model. Description. Fits a Cox proportional hazards regression model. Time dependent ... The proportional hazards model is usually expressed in terms of a single survival time value for each person, with possible ... model. flags to control what is returned. If these are true, then the model frame, the model matrix, and/or the response is ... A strata term identifies a stratified Cox model; separate baseline hazard functions are fit for each strata. The cluster. ...
Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study ... Proportional Hazards Models. Known as: Hazards Models, Proportional, Hazards Model, Proportional, Model, Proportional Hazards ( ... Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study ... Partial least squares proportional hazard regression for application to DNA microarray survival data ...
Proportional Hazard Model:. Proportional hazard model is a generic term for models (particularly survival models in medicine) ... In a proportional hazard model, the effect of an independent variable on the hazard rate is assumed to be multiplicative. For ... Examples of proportional hazard model are exponential, Weibull, and Gompertz models given respectively by ... Cox proposed an ingenious principle for estimating all proportional hazard models without knowing the function h(t) or even the ...
While proportional hazard models are a key instrument for survival analysis within the last centuries, the assumption of hazard ... and significantly reduces the average prediction error compared to the Cox proportional hazards model. ... Schemper, M.: Cox analysis of survival data with non-proportional hazard functions. J. R. Stat. Soc.: Ser. D (Stat.) 41(4), 455 ... Katzman, J.L., Shaham, U., Cloninger, A., Bates, J., Jiang, T., Kluger, Y.: Deep survival: a deep cox proportional hazards ...
Effect of type traits on functional longevity of Czech Holstein cows estimated from a Cox proportional hazards model. Journal ... Effect of type traits on functional longevity of Czech Holstein cows estimated from a Cox proportional hazards model. Journal ... Effect of type traits on functional longevity of Czech Holstein cows estimated from a Cox proportional hazards model. Journal ... Effect of type traits on functional longevity of Czech Holstein cows estimated from a Cox proportional hazards model. Journal ...
The article will promote the use of the joint Cox model in a prospective cohort study. Examples of SAS and S-plus programming ... the joint Cox proportional hazards model is recommended over the polytomous logistic regression model in prospective cohort ... For this reason, an analysis of a real data set was based on the joint Cox proportional hazards model and showed that body size ... A comparison of the polytomous logistic regression and joint cox proportional hazards models for evaluating multiple disease ...
Assessment of contributing risk factors for premature menopause in Bangladesh: Cox proportional hazard model analysis. Sabrina ... "Assessment of contributing risk factors for premature menopause in Bangladesh: Cox proportional hazard model analysis". Family ... "Assessment of contributing risk factors for premature menopause in Bangladesh: Cox proportional hazard model analysis." Family ... Cox proportional hazard model analysis. Family Medicine & Primary Care Review. 2020;22(3):193-196. doi:10.5114/fmpcr.2020.98240 ...
... of under-five children under study is constructed using the estimate of survival function obtained from Coxâ s regression model ... COXS PROPORTIONAL HAZARD MODEL AND CONSTRUCTION OF LIFE TABLE FOR UNDER-FIVE Salam Shantikumar Singh ... of under-five children under study is constructed using the estimate of survival function obtained from Coxâ s regression model ...
"Adjusting for bias introduced by instrumental variable estimation in the Cox proportional hazards model, Biostatistics" on ... the Cox proportional hazards models has become one of the most widely used statistical models due to the ubiquity in medicine ... the Cox proportional hazards models has become one of the most widely used statistical models due to the ubiquity in medicine ... their suitability for estimating Cox proportional hazard models is unclear. It is well known that, in this case, model ...
Comparing a marginal structural model with a Cox proportional hazard model to estimate the effect of time-dependent drug use in ... 2014). Comparing a marginal structural model with a Cox proportional hazard model to estimate the effect of time-dependent drug ... The objective of this study was to compare traditional Cox proportional hazard models (with and without time-dependent ... Cardiovascular disease, Confounding, Marginal structural modeling, Methods, Observational studies, Time-dependent exposure ...
... a right-censored linear model (CLM); 4) a Weibull proportional hazard model (SMW); and 5) a Cox proportional hazard model (SMC ... a Weibull model, a discrete-time model (a proportional hazard model assuming that the survival data are measured on a discrete ... Comparison between a Weibull proportional hazards model and a linear model for predicting the genetic merit of US Jersey sires ... a discrete proportional hazard model, and a binary data analysis using a linear model. Both analytical methods and Monte Carlo ...
Estimation of proportional hazards models when hazards are non-proportional results in coefficient biases and decreased power ... Estimation of proportional hazards models when hazards are non-proportional results in coefficient biases and decreased power ... Estimation of proportional hazards models when hazards are non-proportional results in coefficient biases and decreased power ... Estimation of proportional hazards models when hazards are non-proportional results in coefficient biases and decreased power ...
... 2011-03-25T09:43:23Z. ... Determinants of Inter-Trade Durations and Hazard Rates Using Proportional Hazard Arma Models. * Home ... Determinants of Inter-Trade Durations and Hazard Rates Using Proportional Hazard Arma Models. Publikationstyp:. Working Paper/ ... Determinants of Inter-Trade Durations and Hazard Rates Using Proportional Hazard Arma Models ...
... there cox proportional hazards model assumptions no for! Model ( and any other proportional hazards model is called a semi- ... Cox proportional-hazards model is developed by Cox and published in his work[1] in 1972. The Cox proportional hazards model is ... Model ) has the proportional hazard cox proportional hazards model assumptions the log-linearity assumptions that a must... It ... in 1972 shape of the Cox proportional hazards model is called semi-parametric. Cox proportional hazards model is called a semi- ...
Liu L, Huang X. The use of Gaussian quadrature for estimation in frailty proportional hazards models. Statistics in Medicine. ... Liu, L & Huang, X 2008, The use of Gaussian quadrature for estimation in frailty proportional hazards models, Statistics in ... Liu, L., & Huang, X. (2008). The use of Gaussian quadrature for estimation in frailty proportional hazards models. Statistics ... The use of Gaussian quadrature for estimation in frailty proportional hazards models. In: Statistics in Medicine. 2008 ; Vol. ...
Parametric Proportional Hazards Models. Special cases of the Cox proportional hazards model that follow from assuming a ... Model comparisons. Exponential model = restricted Weibull model with shape parameter \(a = 1\). ... restricted model without IV fitR ,- survreg(Surv(obsT, status) ~ X, dist=weibull, data=dfSurv) anova(fitR, fitWeib) # model ... Parameter tests and model comparisons. Parameter tests. Weibull-model. library(survival) # for survreg() fitWeib ,- survreg( ...
models. PROPORTIONAL. hazards. models. RECEIVER operating characteristic curves. ADVERSE health care events. KAPLAN-Meier ... STRUCTURAL equation modeling. PROPORTIONAL. hazards. models. DATA analysis software. DESCRIPTIVE statistics. KAPLAN-Meier ... models. PHENOMENOLOGICAL biology. PREDICTIVE validity. PROPORTIONAL. hazards. models. RECEIVER operating characteristic curves ... PROPORTIONAL. hazards. models. RETROSPECTIVE studies. DESCRIPTIVE statistics. KAPLAN-Meier estimator. LOG-rank test. Źródło :. ...
new download Tree augmented Cox proportional hazards models, 2008. An oriented while finding this browser. All fits on ... The Circulatory System: Where do I model My lecture? real-time download Tree augmented Cox proportional hazards models of the ... download Tree augmented Cox proportional in Computing training. Your download Tree augmented Cox proportional hazards models ... Though it were as an download Tree augmented Cox proportional hazards models loved with by Abnormalities, IT is paid to aid an ...
Proportional. Hazards. Models. *. Clinical Trials as Topic ; Humans ; Models. , Statistical ; Prognosis ; Risk. Czasopismo ... Proportional. Hazards. Models. * Survival Analysis*. Follow-Up Studies ; Humans ; Leukemia/drug therapy ; Leukemia/mortality ; ... Proportional. Hazards. Models. ; Retrospective Studies ; Survival Analysis ; Tomography, X-Ray Computed ; Tumor Burden. ... Proportional. Hazards. Models. *. HIV Infections/*epidemiology. Cohort Studies ; France/epidemiology ; Humans ; Risk-Taking ; ...
Proportional hazards regression model. Size transition through a firms life cycle is a multi-state process, and transition ... Table 10: Cox proportional hazards regression. Proportional hazards regression on sustainable growth. (Cohort 2003) Estimate. ... Instead, the proportional hazards regression model measures the instant relative "risk" of sustainably scaling up relative to ... The study adopted two types of regression models (logistic and proportional hazards) to assess the association of key factors ...
The Cox proportional hazard model is used to compare the forecasting power of Bharath and Shumways naive model, which retains ... We provide evidence to show that our new model performs better than Bharath and Shumways naive model. In addition, our ... In this paper, we investigate whether the default predictability of the Merton DD model would be affected by taking investors ... However, both the sign and the statistical significance of our model are retained in the CDS spread regressions. ...
  • How to test if proportional hazard assumption holds in parametric survival models that assume Weibull or exponential distribution? (
  • The author describes data-generating processes for the Cox proportional hazards model with time-varying covariates when event times follow an exponential, Weibull, or Gompertz distribution. (
  • The objective of this study was to evaluate the relationship of 20 type traits on length of productive life in Brazilian Holsteins, using a piecewise Weibull proportional hazard model. (
  • and 2) to examine the relationship between genetic parameters from a Weibull model, a discrete proportional hazard model, and a binary data analysis using a linear model. (
  • Data were simulated using the Weibull frailty model with two different shapes of the Weibull distribution. (
  • Three different statistical models were investigated in this study: a Weibull model, a discrete-time model (a proportional hazard model assuming that the survival data are measured on a discrete scale with few classes), and a linear model based upon binary data. (
  • An alternative derivation using basic expressions of reliabilities in sire models suggests a simple equation for the heritability on the original scale (effective heritability) that is not dependent on the Weibull parameters. (
  • In general, the estimates of reliability from either the discrete model or the binary data analysis were close to estimates from the Weibull model for a given number of uncensored records in this simplified case of a balanced design. (
  • Although selection response from the binary data analysis depends on the end of interval point, there is a relatively good agreement between selection responses in the Weibull model and the binary data analysis. (
  • Comparison between a Weibull proportional hazards model and a linear model for predicting the genetic merit of US Jersey sires for daughter longevity. (
  • Predicted transmitting abilities (PTA) of US Jersey sires for daughter longevity were calculated using a Weibull proportional hazards sire model and compared with predictions from a conventional linear animal model. (
  • The effect of ignoring individual heterogeneity in Weibull log-normal sire frailty models. (
  • The objective of this study was, by means of simulation, to quantify the effect of ignoring individual heterogeneity in Weibull sire frailty models on parameter estimates and to address the consequences for genetic inferences. (
  • Data were simulated according to balanced half-sib designs using Weibull log-normal animal frailty models with a normally distributed residual effect on the log-frailty scale. (
  • Likewise, if a baseline Weibull distribution aft model is used, the parameter estimates are just a linear transformation of those used in the proportional hazards model with Weibull baseline distribution. (
  • In another design - the Weibull proportional hazards design - the failure times are presumed to follow a theoretical circulation understood as the Weibull circulation. (
  • Adejumo, A. O. and Ahmadu, A. O. (2016) A Study of the Slope of Cox Proportional Hazard and Weibull Models. (
  • Gradient Curve of Cox Proportional Harzard and Weibull Models. (
  • Gompertz PH and Weibull AFT models were used for survival analysis (SA) of these patients. (
  • Also, in the Weibull model, birth place and age at onset of the disease were significant factors (p= 0.013, and p= 0.008) in survival time. (
  • The Akaike Information Criterion (AIC) for Weibull model was 158.51, which was lower than other parametric models. (
  • According to the results, the Weibull AFT model was found to be a better model for identifying the risk factors related to survival of patients with TM disease. (
  • In a pdf model based recursive partitioning with adjustment for measurement error applied to the coxs proportional hazards and weibull model of 3,626 boys with biological relationships, miles continued used just of matroid magnets to get terms. (
  • To compare the semi-parametric Cox model and parametric [including exponential, Weibull, Gompertz, log-normal, log-logistic and gamma] models and find the best model fitted to studied data, Akaike's Information Criterion [AIC] and Cox-Snell residual were used. (
  • the best known being the Cox semiparametric proportional hazards model , [1] [3] and the exponential, Gompertz and Weibull parametric models. (
  • Survival models relate the time that passes, before some event occurs, to one or more covariates that may be associated with that quantity of time. (
  • and the effect parameters, describing how the hazard varies in response to explanatory covariates. (
  • The proportional hazards condition states that covariates are multiplicatively related to the hazard. (
  • The effect of covariates estimated by any proportional hazards model can thus be reported as hazard ratios. (
  • This is a partial likelihood: the effect of the covariates can be estimated without the need to model the change of the hazard over time. (
  • This paper also provides a variance inflation factor together with simulations for adjustment of sample size when additional covariates are included in the model. (
  • where L is the hazard function or hazard rate, {x i } are covariates, {b i } are coefficients of the model - effects of the corresponding covariates, and h(t) gives the effect of duration on the hazard rate. (
  • The objective of this study was to compare traditional Cox proportional hazard models (with and without time-dependent covariates) with MSM to study causal effects of time-dependent drug use. (
  • No multicollinearity among covariates his work [ 1 ] in 1972 any fitting to ensure cox proportional hazards model assumptions underlying is! (
  • Simulated survival time \(T\) influenced by time independent covariates \(X_{j}\) with effect parameters \(\beta_{j}\) under assumption of proportional hazards, stratified by sex. (
  • The algorithms are extended to models with time-dependent covariates. (
  • The proportional hazards design was presented in 1972 by D. R. Cox in order to approximate the results of various covariates affecting the times to the failures of a system. (
  • 9 covariates were selected to fit colorectal cancer data using Cox Regression Models. (
  • Cox proportional hazards models are used to model survival time using covariates. (
  • The principle of the Cox proportional hazards model is to link the survival time of an individual to covariates. (
  • Key topics covered include: variable selection, identification of the scale of continuous covariates, the role of interactions in the model, assessment of fit and model assumptions, regression diagnostics, recurrent event models, frailty models, additive models, competing risk models, and missing data. (
  • 1995) give more detail on regression dilution in nonlinear models, presenting the regression dilution ratio methods as the simplest case of regression calibration methods, in which additional covariates may also be incorporated. (
  • Patient centered hazard ratio estimation using principal stratification weights: application to the norccap randomized trial of colorectal cancer screening. (
  • Bias in estimating the causal hazard ratio when using two-stage instrumental variable methods. (
  • The differences for hazards ratio are expressed as 0-1 for dichotomic variables, as 1 unit for physical activity, and as standard deviations for continuous variables. (
  • For each hazard ratio the 95% confidence interval for the population hazard ratio is presented, providing an interval estimate for the population parameter. (
  • The hazard ratio for mortality in relation to duration at 2.4 years was 0.85, 95% CI=0.83-0.87. (
  • 80% was associated with poorer survival, hazard ratio 1.10, 95% CI=1.001-1.21. (
  • The quantities \(exp(b_i)\) are called hazard ratios (HR). A value of \(b_i\) greater than zero, or equivalently a hazard ratio greater than one, indicates that as the value of the \(i^{th}\) covariate increases, the event hazard increases and thus the length of survival decreases. (
  • Put another way, a hazard ratio above 1 indicates a covariate that is positively associated with the event probability, and thus negatively associated with the length of survival. (
  • In the majority of scenarios, we have an interest in comparing groups with regard to their hazards, and we utilize a danger ratio, which is comparable to a chances ratio in the setting of several logistic regression analysis . (
  • This hazard ratio (HR) for the outcome-often interpreted as a type of relative risk-is the effect of interest and may be used in epidemiological studies for risk assessment. (
  • It means that the hazard ratio between two different observations does not depend on time. (
  • In survival analysis , the hazard ratio ( HR ) is the ratio of the hazard rates corresponding to the conditions described by two levels of an explanatory variable. (
  • The hazard ratio would be 2, indicating higher hazard of death from the treatment. (
  • Or in another study, men receiving the same treatment may suffer a certain complication ten times more frequently per unit time than women, giving a hazard ratio of 10. (
  • This hazard ratio, that is, the ratio between the predicted hazard for a member of one group and that for a member of the other group, is given by holding everything else constant, i.e. assuming proportionality of the hazard functions. (
  • In its simplest form, the hazard ratio can be interpreted as the chance of an event occurring in the treatment arm divided by the chance of the event occurring in the control arm, or vice versa, of a study. (
  • The hazard ratio is simply the relationship between the instantaneous hazards in the two groups and represents, in a single number, the magnitude of distance between the Kaplan-Meier plots. (
  • [1] When a study reports one hazard ratio per time period, it is assumed that difference between groups was proportional. (
  • If the proportional hazard assumption holds, a hazard ratio of one means equivalence in the hazard rate of the two groups, whereas a hazard ratio other than one indicates difference in hazard rates between groups. (
  • Hughes (1993) shows that the regression dilution ratio methods apply approximately in survival models. (
  • Rosner (1992) shows that the ratio methods apply approximately to logistic regression models. (
  • This web page accompanies the paper The Dantzig selector in Cox's proportional hazards model by Anestis Antoniadis , Piotr Fryzlewicz and Frederique Letue . (
  • At the bottom of this page, you can download R code implementing the main algorithm of the paper: the Dantzig selector for Cox's proportional hazards model. (
  • Using instrumental variables to estimate a Cox's proportional hazards regression subject to additive confounding. (
  • We investigate the proportionality assumption for Cox's semiparametric model in the context of the "liberal peace" debate, using data on international conflict in the postwar period. (
  • In the most popular of these models - Cox's proportional hazards design - no hidden circulation of failure times is presumed. (
  • Fujimori, K & Nishiyama, Y 2017, ' The l q consistency of the Dantzig selector for Cox's proportional hazards model ', Journal of Statistical Planning and Inference , vol. 181, pp. 62-70. (
  • Cox's proportional hazards (CPH) model is a nonparametric method, which means that it makes no assumptions about the distribution of the response measure. (
  • The hazards of hazard ratios. (
  • A key assumption of nearly all widely used duration models is that the hazard ratios (i.e., the conditional relative risks across substrata) are proportional to one another and that this proportionality is maintained over time. (
  • Hazards ratios (HRs) and 95% confidence intervals (CIs) were calculated among the larger cohort (n=27,035). (
  • Cox analysis revealed that TB-related mortality hazard ratios included treatment default (8.9), multidrug resistance (5.7), recently transmitted TB (4.1), weight loss (3.9), and hav- ing less than 6 years of formal education (2). (
  • Hazard ratios differ from relative risks and odds ratios in that RRs and ORs are cumulative over an entire study, using a defined endpoint, while HRs represent instantaneous risk over the study time period, or some subset thereof. (
  • Hazard ratios suffer somewhat less from selection bias with respect to the endpoints chosen and can indicate risks that happen before the endpoint. (
  • Regression models are used to obtain hazard ratios and their confidence intervals . (
  • Hazard ratios do not reflect a time unit of the study. (
  • Hazard ratios become meaningless when this assumption of proportionality is not met. (
  • Excess risk in the four months after acute infection and hazard ratios with Bonferroni corrected 95% confidence intervals were calculated. (
  • 0.001), and hazard ratios ranged from 1.24 to 25.65 compared with the 2020 comparator group. (
  • In statistics and regression analysis , proportional hazards models are "statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study population is multiplicative and does not change over time. (
  • An alternative method is the Cox proportional hazards regression analysis, which works for both quantitative predictor variables and for categorical variables. (
  • They explain the survival inning accordance with one aspect under examination, however overlook the effect of other.An option approach is the Cox proportional hazards regression analysis , which works for both quantitative predictor variables and for categorical variables. (
  • A counting process approach to maximum likelihood estimation in frailty models. (
  • Estimation of multivariate frailty models using penalized partial likelihood. (
  • Two-stage residual inclusion estimation: addressing endogeneity in health econometric modeling. (
  • Estimation of proportional hazards models when hazards are non-proportional results in coefficient biases and decreased power of significance tests. (
  • In paper, we propose a novel Gaussian quadrature estimation method in various frailty proportional hazards models. (
  • Liu, L & Huang, X 2008, ' The use of Gaussian quadrature for estimation in frailty proportional hazards models ', Statistics in Medicine , vol. 27, no. 14, pp. 2665-2683. (
  • In my presentation I will describe the stochastic gradient descent algorithm that was applied in the log- likelihood estimation process of coefficients' calcualtions of the Cox proportional hazards model. (
  • Adaptive Penalized Weighted Least Absolute Deviations Estimation for the Accelerated Failure Time Model. (
  • We consider the estimation of the semiparametric proportional hazards model with an unspecified baseline hazard function where the effect of a continuous covariate is assumed to be monotone. (
  • Previous work on nonparametric maximum likelihood estimation for isotonic proportional hazard regression with right-censored data is computationally intensive, lacks theoretical justification, and may be prohibitive in large samples. (
  • Fine, Jason P. / Partial likelihood estimation of isotonic proportional hazards models . (
  • In particular, MMPH models allow for the estimation of several durations per individual. (
  • Marafa Haliru Muhammad, Usman Umar, Estimation of Population Based Colorectal Cancer Survival Analysis Using Cox Proportional Hazards Model, Biomedical Statistics and Informatics . (
  • Non-parametric estimation of the survival and cumulative hazard functions. (
  • It includes imputation methods for dealing with missing data effectively, methods for dealing with nonlinear relationships and for making the estimation of transformations a formal part of the modeling process, methods for dealing with "too many variables to analyze and not enough observations," and powerful model validation techniques based on the bootstrap. (
  • It starts with the tests of hypotheses and moves on to regression modeling, time-to-event analysis, density estimation, and resampling methods. (
  • The author also describes time-to-event nonparametric estimation methods, such as the Kaplan-Meier survival curve and Cox proportional hazards model, and presents histogram and kernel density estimation methods. (
  • The objective of this study is to investigate the problem of goodness of fit testing based on nonparametric function estimation techniques for the random censorship model. (
  • Math Nauk 1987 no.3 Estimation of Probability Density and the Hazard Rate Function in the Koziol-Green Model of Random Censorship Abdushukurov, A.A. (
  • Statistics v.19 Maximum Likelihood Estimation of a survival Function under the Koziol-Green Proportional hazards model of random censorship Cheng, P.E.;Lin, G.D. (
  • Statistics v.19 Estimation in the proportional hazards model of random censorship Csorgo, S. (
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  • We present a bootstrap resampling plan for the Cox partial likelihood estimator for proportional hazards models with nonrandom explanatory variables. (
  • The Cox partial likelihood, shown below, is obtained by using Breslow's estimate of the baseline hazard function, plugging it into the full likelihood and then observing that the result is a product of two factors. (
  • This function can be maximized over β to produce maximum partial likelihood estimates of the model parameters. (
  • The exact method computes the exact partial likelihood, which is equivalent to a conditional logistic model. (
  • Simulation studies show that our method compares favorably with the well-received penalized partial likelihood method and the Monte Carlo EM (MCEM) method, for both normal and Gamma frailty models. (
  • Maximum likelihood estimates of the regression parameters, the variance components and the baseline hazard function are obtained via the EM algorithm. (
  • The iterative convex minorant algorithm which uses pool-adjacent-violators techniques has also been shown to perform well in related parametric likelihood set-ups, but evidences computational difficulties under the proportional hazards model. (
  • A class of variable selection procedures for parametric models via nonconcave penalized likelihood was proposed in Fan and Li (2001a). (
  • In this paper, the nonconcave penalized likelihood approach is extended further to the Cox proportional hazards model and the Cox proportional hazards frailty model, two commonly used semi-parametric models in survival analysis. (
  • G. Kauermann and U. Berger, "A smooth test in proportional hazard survival models using local partial likelihood fitting", LIFETIME DATA ANALYSIS , vol. 9, 2003, pp. 373-393. (
  • In linear and logistic regression models, the ridge regression estimator has been applied as an alternative to the maximum likelihood estimator in the presence of collinearity. (
  • We also characterize the conditions for improper survival functions and the conditions for existence of the maximum likelihood estimates under the proposed ELTH models. (
  • To estimate the β parameters of the model (the coefficients of the linear function), we try to maximize the partial likelihood function. (
  • Sir David Cox observed that if the proportional hazards assumption holds (or, is assumed to hold) then it is possible to estimate the effect parameter(s) without any consideration of the hazard function. (
  • The use of restricted mean survival time to estimate the treatment effect in randomized clinical trials when the proportional hazards assumption is in doubt. (
  • Further, a life table of under-five children under study is constructed using the estimate of survival function obtained from Coxâ s regression model. (
  • We address the potential problems with incorrectly assuming proportionality, illustrate a number of tests for non-proportionality, and conclude with a discussion of how to accurately and efficiently estimate these models in the presence of nonproportional hazards. (
  • Time-to-event data can be used to compute descriptive statistics, estimate parametric and nonparametric distributions, fit a variety of survival models, and perform hypothesis tests. (
  • In labor and population economics, the Mixed Proportional Hazard (MPH) model and its multivariate extensions, the so-called Multivariate Mixed Proportional Hazard (MMPH) models, are state of the art and the most widely used models to estimate durations and their determinants. (
  • The aim of this study is to estimate the population based colorectal cancer survival analysis using cox Proportional Hazards model, in order to fits colorectal cancer data in population-based research. (
  • The proportional hazard model could steadily estimate the ETA for longevity of the sires in Japan. (
  • Some of the underlying theory is discussed, including Cox regression to estimate parameters of the model. (
  • A Cox model provides an estimate of the treatment effect on survival after adjustment for other explanatory variables. (
  • It allows us to estimate the hazard (or risk) of death, or other event of interest, for individuals, given their prognostic variables. (
  • If we only estimate the second term, a very important hypothesis has to be verified: the proportional hazards hypothesis. (
  • is the estimate of treatment effect derived from the regression model. (
  • In general, methods for the structural model require some estimate of the variability of the x variable. (
  • In a proportional hazards model, the unique effect of a unit increase in a covariate is multiplicative with respect to the hazard rate. (
  • This expression gives the hazard function at time t for subject i with covariate vector (explanatory variables) Xi. (
  • This paper derives a formula to calculate the number of deaths required for a proportional hazards regression model with a nonbinary covariate. (
  • Simulations show that the censored observations do not contribute to the power of the test in the proportional hazards model, a fact that is well known for a binary covariate. (
  • Background: The appropriate handling of missing covariate data in prognostic modelling studies is yet to be conclusively determined. (
  • Effects of covariate omission and categorization when analysing randomized trials with the Cox model. (
  • Proportional hazard models for survival data, even though popular and numerically handy, suffer from the restrictive assumption that covariate effects are constant over survival time. (
  • This paper contributes to this area by employing local estimates allowing to fit hazard models in which covariate effects are smoothly varying with time. (
  • Assessing time-by-covariate interactions in proportional hazards regression models using cubic spline functions. (
  • Exploring the nature of covariate effects in the proportional hazards model. (
  • The course focuses on the Cox proportional hazards model, not the parametric models, and is not designed for predictive modelers. (
  • 2017) Comparison of Cox Regression and Parametric Models. (
  • This study aimed to compare the results of the use of the semi-parametric Cox model with parametric models to determine the factors influencing the length of stay of patients in the inpatient units of Women Hospital in Tehran, Iran . (
  • We use a semiparametric proportional hazard model which is augmented by an ARMA structure very similar to the wide spread ACD model to obtain consistent estimates of the baseline survivor function and to capture well known serial dependencies in the trade intensity process. (
  • In: Jewell N.P., Kimber A.C., Lee ML.T., Whitmore G.A. (eds) Lifetime Data: Models in Reliability and Survival Analysis. (
  • This approach to survival data is called application of the Cox proportional hazards model, sometimes abbreviated to Cox model or to proportional hazards model. (
  • To actually run the model, you will need to enter the data into a hazard model regression calculator, which can be found online . (
  • a missing-data filter function, applied to the model.frame, after any subset argument has been used. (
  • A key element in any statistical simulation is the existence of an appropriate data-generating process: one must be able to simulate data from a specified statistical model. (
  • This course will teach you the various methods used for modeling and evaluating survival data or time-to event data. (
  • While proportional hazard models are a key instrument for survival analysis within the last centuries, the assumption of hazard proportionality might be overly restrictive and their applicability to complex data remains difficult. (
  • The model is evaluated on multiple datasets, including metastatic colorectal cancer computed tomography imaging data, and significantly reduces the average prediction error compared to the Cox proportional hazards model. (
  • A resampling study was performed to investigate the effects of different missing data methods on the performance of a prognostic model. (
  • Frailty models for survival data. (
  • When studying the causal effect of drug use in observational data, marginal structural modeling (MSM) can be used to adjust for time-dependent confounders that are affected by previous treatment. (
  • What I have done so far: used 9 months of data to fit the model and 3 remaining months as a holdout validation set. (
  • From an inspection of conditional transaction probabilities based on Bund future transaction data of the DTB we find a decreasing hazard shape providing evidence for the use of non-trading intervals as an indication for the absence of price information among market participants. (
  • If we take the functional form of the survival function defined above and apply the following transformation, we arrive at: Cox Model has the proportional hazard and the log-linearity assumptions that a data must satisfy. (
  • Proportional Hazards Models What if the data fails to satisfy the assumptions? (
  • It is the most commonly used regression model for survival data. (
  • Most commonly used regression model for survival data 1 ] in 1972 it 's important test. (
  • Doing it the log-linearity assumptions that a data must satisfy forward to do so in R. there cox proportional hazards model assumptions no for! (
  • Has the proportional hazard and the log-linearity assumptions that a data must satisfy assumption is n't violated Cox hazards! (
  • We first apply our method to simple frailty models for correlated survival data (e.g. recurrent or clustered failure times), then to joint frailty models for correlated failure times with informative dropout or a dependent terminal event such as death. (
  • We apply our method to three real data examples: (1) the time to blindness of both eyes in a diabetic retinopathy study, (2) the joint analysis of recurrent opportunistic diseases in the presence of death for HIV-infected patients, and (3) the joint modeling of local, distant tumor recurrences and patients survival in a soft tissue sarcoma study. (
  • We propose a general proportional hazards model with random effects for handling clustered survival data. (
  • The cox proportional-hazards model is one of the most important methods used for modelling survival analysis data. (
  • T o illustrate the model, unde r - fi v e child surv iv al data e xtracted from Bangladesh Demogr a phic and Health Sur ve y 2014 h a v e been used. (
  • The Cox PH model, because it is built on top of a nonparametric baseline hazard rate, cannot extrapolate to loan ages that are not observed in the data set. (
  • The logistic model treats the age of the loan as a continuous variable, and, therefore, it can extrapolate to predict PDs for ages not observed in the data set. (
  • If, for a particular age, the PD is small and there are no observed defaults in the data, the Cox PH model predicts the PD as zero. (
  • May, M. Royston, P. Egger, M. Justice, A. C. and Sterne, J.A.C. (2004) Development and Validation of Prognosis Model for Survival Time Data: Application to Prognosis of HIV Positive Patients Treated with Anti-retroviral Therapy. (
  • The Cox proportional hazards (PH) model is frequently used to model survival data or time-to-event data, particularly in the presence of censored survival times [ 1 ]. (
  • Also the results show that the data met Cox Proportional Hazards Assumptions. (
  • Applied Survival Analysis: Regression Modeling of Time- to- Event Data. (
  • Joeng, HK, Chen, MH & Kang, S 2016, ' Proportional exponentiated link transformed hazards (ELTH) models for discrete time survival data with application ', Lifetime Data Analysis , vol. 22, no. 1, pp. 38-62. (
  • 2. Introduction H2O is an open source, in-memory, distributed, fast, and scalable machine learning and predictive analytics platform Build machine learning models on big data and provides easy productionalization of those models in an enterprise environment. (
  • Objects in the H2O cluster such as data frames, models and results are all referenced by key. (
  • Instead of presenting isolated techniques, this text emphasizes problem solving strategies that address the many issues arising when developing multivariable models using real data and not standard textbook examples. (
  • Working through the case studies in the book will demonstrate what can be achieved with a little imagination, when modelling complex and challenging data sets. (
  • Hello, I am a statistician with 2+ years of experience in statistical modeling, data mining, survival analysis, and data visualization on data to derive predictive business insight. (
  • Hi, I have strong statistical background and I have an experince in statistical modelling , analysis and handling data. (
  • The concept of censored data is discussed, and the proportional hazards model is introduced. (
  • The proportional hazards model has been developed by Cox (1972) in order to treat continuous time survival data. (
  • Applied Survival Analysis, Second Edition provides a comprehensive and up-to-date introduction to regression modeling for time-to-event data in medical, epidemiological, biostatistical, and other health-related research. (
  • This book fills this gap, providing a comprehensive, self-contained introduction to regression modeling used in the analysis of time-to-event data in epidemiological, biostatistical, and other health-related research. (
  • Most prediction models are developed using a regression model, such as linear regression for continuous outcomes (eg, pain score), logistic regression for binary outcomes (eg, presence or absence of pre-eclampsia), or proportional hazards regression models for time-to-event data (eg, recurrence of venous thromboembolism). (
  • Statisticians call this problem censoring , a problem that surfaces when you try to model a time-to-event response measure using data captured over a limited time period. (
  • Thus, it is often informative to examine the hazard function when time to response data is being analyzed. (
  • In this study Cox proportional hazard model is fitted to patient data of Acute Myeloid Leukemia. (
  • Journal of the American Statistical Association v.74 Nonparametric Statistics Data Modeling Parazen, E. (
  • The course also introduces and explains the concept of modelling survival data based on the widely-use Cox regression model. (
  • The method does not require assumptions about the distributions of survival time and predictor variables other than proportional hazards. (
  • The Cox proportional-hazards model (Cox, 1972) is essentially a regression model commonly used statistical in medical research for investigating the association between the survival time of patients and one or more predictor variables. (
  • The Cox proportional hazard model is basically a regression model generally used by medical researchers to find out the relationship between the survival time of a subject and one or more predictor variables. (
  • From the results, it was concluded that the predictor variables could significantly predict the survival of colorectal cancer patients using Cox proportional model. (
  • CPH models the underlying hazard rate (for example, risk of death) as a function of a baseline hazard rate and the incremental effects of predictor variables. (
  • 1978). The case of multiple predictor variables subject to variability (possibly correlated) has been well-studied for linear regression, and for some non-linear regression models. (
  • Groups were compared by Cox proportional hazard models and Kaplan-Meier survival plots. (
  • The Cox PH model has a nonparametric baseline hazard rate that can match patterns in the PDs much more closely than the fully parametric logistic model. (
  • The book covers, very completely, the nuances of regression modeling with particular emphasis on binary and ordinal logistic regression and parametric and nonparametric survival analysis. (
  • It then discusses smoothing techniques (loess and thin-plate splines) for classical nonparametric regression as well as binary logistic and Poisson models. (
  • By using statistical modelling, we can assess the extent to which the increased risk of COVID-19 mortality in some religious groups is explained by differences in these factors at the population level. (
  • We model the risk of death involving COVID-19 for the whole outcome period, and separately for the first and second waves of the pandemic to explore whether differences in the risk of COVID-19 mortality between different religious groups have changed over time. (
  • The hazard, or instantaneous risk, of an event of interest, typically mortality or morbidity, is modeled in terms of one or more explanatory variables relative to an unspecified baseline hazard rate. (
  • Proportional Hazards Model Assumption Let \(z = \{x, \, y, \, \ldots\}\) be a vector of one or more explanatory variables believed to affect lifetime. (
  • In an alternative group of models, the explanatory variables act multiplicatively straight on the failure time. (
  • In occupational settings, it is common to have an occupational exposure as one of the explanatory variables in the model and the association between the outcome and this exposure is of interest. (
  • A Cox model is a well-recognized statistical technique for exploring the relationship between the survival of a patient and several explanatory variables. (
  • The natural log of the hazard function is the response and two of the explanatory variables age and cellularity level of the patient. (
  • We develop methods for comparative APC analysis of two independent cause-specific hazard rates assuming that an APC model holds for each one. (
  • In the previous chapter (survival analysis basics), we described the basic concepts of survival analyses and methods for analyzing and summarizing … The proportional hazards assumption is probably one of the best known modelling assumptions with regression and is unique to the cox model. (
  • Furthermore, the Cox regression model extends survival analysis methods to assess simultaneously the effect of several risk factors on survival time. (
  • One of the most popular regression methods for survival analysis is Cox proportional hazards regression, which is utilized to relate a number of threat elements or direct exposures, thought about concurrently, to survival time. (
  • Statistical Methods in Credit Risk Modelling, University of Michigan, 3 4-27. (
  • Truncated power basis expansions and penalized spline methods are demonstrated for estimating nonlinear exposure-response relationships in the Cox proportional hazards model. (
  • Methods for modeling nonlinearities are needed in those situations when a linear exposure-response is not expected or when one desires to formally assess a nonlinear association. (
  • Many different types of models and methods are discussed. (
  • Since publication of the first edition nearly a decade ago, analyses using time-to-event methods have increased considerably in all areas of scientific inquiry, mainly as a result of model-building methods available in modern statistical software packages. (
  • The reply to Frost & Thompson by Longford (2001) refers the reader to other methods, expanding the regression model to acknowledge the variability in the x variable, so that no bias arises. (
  • Supplied penalty functions include ridge regression ( ridge ), smoothing splines ( pspline ), and frailty models ( frailty ). (
  • Frailty Models in Survival Analysis. (
  • The proposed method greatly simplifies the implementation of the (joint) frailty models and makes them much more accessible to general statistical practitioners. (
  • The Cox model can be written as a multiple linear regression of the logarithm of the hazard on the variables \(x_i\) , with the baseline hazard being an 'intercept' term that varies with time. (
  • We show, based on an exogenous information process, that the way traders aggregate information has implications for the shape of the hazard function. (
  • assumes parametric form for the effect of the predictors on the hazard In most situations, we are more interested in the parameter estimates than the shape of the hazard. (
  • Mathematics & Statistics (Sci) : Distribution theory, stochastic models and multivariate transformations. (
  • We approximate the unspecified baseline hazard by a piecewise constant one, resulting in a parametric model that can be fitted conveniently by Gaussian quadrature tools in standard software such as SAS Proc NLMIXED. (
  • I need an expert in R who knows cox proportional hazard model to help fit a piecewise exponential baseline hazard. (
  • Hi, I am analyzing the influence of some variables on the probability of failure in the sample of firms using parametric survival model in STATA. (
  • We propose a deep model for computed-tomography-based survival analysis providing a hazard probability output representation comparable to Cox regression without relying on the hazard proportionality assumption. (
  • The Cox proportional hazard model is used to compare the forecasting power of Bharath and Shumway's naive model, which retains the functional form of the Merton DD model and computes the default probability in a naive way, with our new model, which treats investors' ambiguity aversion as additional information. (
  • The hazard function is the probability that an individual will experience an event (for example, death) within a small time interval, given that the individual has survived up to the beginning of the interval. (
  • a) complete case analysis (CC) b) single imputation using regression switching with predictive mean matching (SI), c) multiple imputation using regression switching imputation, d) multiple imputation using regression switching with predictive mean matching (MICE-PMM) and e) multiple imputation using flexible additive imputation models. (
  • Instrumental variable additive hazards models. (
  • Participants will be assumed to have some knowledge of elementary statistical techniques (e.g. hypothesis testing, standard errors and confidence intervals) and linear regression (e.g. concept of a statistical model, comparing models). (
  • This article reports age-standardised rates of death involving the coronavirus (COVID-19) by religious group and uses statistical models to adjust for location, measures of disadvantage, occupation, living arrangements, and pre-existing health conditions. (
  • Statistical Models Based on Counting Process. (
  • 1999) Variation over Time of the Effects of Prognostic Factors in a Population based Study of Colon Cancer: Comparison of Statistical Models. (
  • separate baseline hazard functions are fit for each strata. (
  • Although the Cox model makes no assumptions about the distribution of failure times, it does assume that hazard functions in the different strata are proportional over time - the so-called proportional hazards assumption. (
  • Cox proportional-hazards model is developed by Cox and published in his work[1] in 1972. (
  • The subject of this appendix is the Cox proportional-hazards regression model introduced in a seminal paper by Cox, 1972, a broadly applicable and the most widely used method of survival analysis. (
  • This generalizes the usual frailty model by allowing a multivariate random effect with arbitrary design matrix in the log relative risk, in a way similar to the modelling of random effects in linear, generalized linear and non-linear mixed models. (
  • In the simplest case of stationary coefficients, for example, a treatment with a drug may, say, halve a subject's hazard at any given time t {\displaystyle t} , while the baseline hazard may vary. (
  • A Cox proportional hazards model was fitted to each dataset and estimates for the regression coefficients and model performance measures obtained. (
  • Interpreting a Cox model involves examining the coefficients for each explanatory variable. (
  • The fitted model based on three different hazard function revealed, that estimates of the regression coefficients and their relevant standard error are quit close when h2(t) and h3(t) are used as hazard rate. (
  • Cox proposed an ingenious principle for estimating all proportional hazard models without knowing the function h(t) or even the base hazard rate h 0 (t). (
  • The survival analysis allows to combine information from live (censored) and culled (uncensored) animals to model the nonlinear, the time-dependent factors influencing productive life, and describe of the evolution of a hazard function throughout the cow productive life ( Ducrocq, 2005 Ducrocq, V. 2005. (
  • This paper puts a focus on the hazard function of inter-trade durations to characterize the intraday trading process. (
  • The Cox proportional hazards model is called a semi-parametric model, because there are no assumptions about the shape of the baseline hazard function. (
  • Because there are no assumptions about the shape of the baseline hazard function must satisfy baseline. (
  • The Cox model is expressed by the hazard function denoted by h(t). (
  • Briefly, the hazard function can be interpreted as the risk of dying at time t. (
  • A separate estimator of the baseline hazard function is provided. (
  • Displays diagnostics graphs presenting goodness of Cox Proportional Hazards Model fit, that can be calculated with coxph function. (
  • A function to create a regular grid over an observation window in order to model the spatial randome effects as a Gaussian Markov random field. (
  • 3.5 Estimating the Survival Function of the Proportional Hazards Regression Model. (
  • Survival pattern can be conveniently inspected with the help of hazard function. (
  • Three different forms of the hazard rates are incorporated in the hazard function and are tried out as response. (
  • Discrete proportional hazards models for mismeasured outcomes. (
  • An extensive simulation study is conducted to examine the empirical performance of the parameter estimates under the Cox proportional hazards model by treating discrete survival times as continuous survival times, and the model comparison criteria, AIC and BIC, in determining links and baseline hazards. (
  • 3.4 Fitting the Proportional Hazards Model with Tied Survival Times. (
  • The proportional hazards model included time-dependent effects of herd-year-season contemporary group and parity by stage of lactation interaction, as well as time-independent effects of sire and age at first calving. (
  • To avoid this mean adjustment, we can manually generate the predicted log of hazard using the parameter estimates as shown below. (
  • Other HR models have different formulations and the interpretation of the parameter estimates differs accordingly. (
  • The Dantzig selector for the proportional hazards model proposed by D.R. Cox is studied in a high-dimensional and sparse setting. (
  • In the Gompertz model, birthplace and age at onset of the disease were significant factors (p= 0.035, and p= 0.005) in survival time. (
  • Age-period-cohort (APC) analysis is widely used in cancer epidemiology to model trends in cancer rates. (
  • We construct linear hypothesis tests to determine whether the two hazards are absolutely proportional or proportional after stratification by cohort, period, or age. (
  • In the case of the exponential distribution, the proportional hazards and aft model are equivalent, so if distribution is set to exponential, this is a proportional hazards model with an exponential baseline. (
  • Basic quantifiers of survival: survival, hazard and cumulative hazard functions. (
  • Campbell, Hilscher and Szilagyi [ 2 ] concluded that the strong predictive power of the Merton DD model came from the functional form imposed by the Merton model. (
  • in predictive modelling applications, correction is neither necessary nor appropriate. (
  • In predictive modelling, no. (
  • begingroup$ @seanv507 Yes, I'm very new to Survival analysis as explained, I'm even considering doing a Logistic Regression for each period, but I also would like to learn more about Survival models. (
  • When the proportional hazards hypothesis does not hold, the model can be stratified. (
  • This course begins with an overview and continues to cover the following topics: summary statistics and exploratory graphics, simple hypothesis testing, regression modelling using the Cox model and some extensions to this model. (
  • It also shows how to fit a Cox proportional hazards (PH) model, also known as Cox regression, to predict PDs. (
  • In survival analysis several regression modeling strategies can be applied to predict the risk of future events. (
  • Clinical prediction models aim to predict outcomes in individuals, to inform diagnosis or prognosis in healthcare. (
  • 8 9 Such models allow health professionals to predict an individual's outcome value, or to predict an individual's risk of an outcome being present (diagnostic prediction model) or developed in the future (prognostic prediction model). (
  • Use of FLIM histology-based HER2-HER3 heterodimer quantification and a Bayesian latent class proportional hazards model to predict cetuximab response in the COIN and new EPOC trials. (