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

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 ...