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*  "Propensity score methods : a simulation and case study involving breas" by John Craycroft
Observational data presents unique challenges for analysis that are not encountered with experimental data resulting from carefully designed randomized controlled trials. Selection bias and unbalanced treatment assignments can obscure estimations of treatment effects, making the process of causal inference from observational data highly problematic. In 1983, Paul Rosenbaum and Donald Rubin formalized an approach for analyzing observational data that adjusts treatment effect estimates for the set of non-treatment variables that are measured at baseline. The propensity score is the conditional probability of assignment to a treatment group given the covariates. Using this score, one may balance the covariates across treatment groups and obtain unbiased estimates of treatment effects. This paper has three objectives: to explain propensity scores, their assumptions, and their applications; to illustrate their use and several ...
http://ir.library.louisville.edu/etd/2460/
*  Health Outcomes with and without Use of Inotropic Therapy in Cardiac Surgery:Results of a Propensity Score-matched Analysis |...
Missing data could be a source of uncontrolled bias. However, due to the low range of missing data in our data, it is unlikely to influence the results significantly. It is also important to note that patients who only received vasopressor therapy were completely excluded from the analysis. This is a unique population that may actually do better than patients represented in the current article. Despite these limitations, we believe the results show an underlying signal regarding the potentially harmful effect of perioperative inotropic therapy. Our results support the findings of two other important observational studies. Fellahi et al. reported that catecholamine administration was associated with major cardiac morbidity. In an initial cohort of 667 patients, perioperative use of catecholamines was associated with increased cardiac morbidity measured as a combined endpoint of postoperative sustained ventricular arrhythmia, need for an intraaortic balloon pump in ICU or postoperative MI. The ...
http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1917759
*  Propensity score analysis in the Genetic Analysis Workshop 17 simulated data set on independent individuals | BMC Proceedings |...
Genetic Analysis Workshop 17 provided simulated phenotypes and exome sequence data for 697 independent individuals (209 case subjects and 488 control subjects). The disease liability in these data was influenced by multiple quantitative traits. We addressed the lack of statistical power in this small data set by limiting the genomic variants included in the study to those with potential disease-causing effect, thereby reducing the problem of multiple testing. After this adjustment, we could readily detect two common variants that were strongly associated with the quantitative trait Q1 (C13S523 and C13S522). However, we found no significant associations with the affected status or with any of the other quantitative traits, and the relationship between disease status and genomic variants remained obscure. To address the challenge of the multivariate phenotype, we used propensity scores to combine covariates with genetic risk factors into a single risk factor and created a new ...
https://bmcproc.biomedcentral.com/articles/10.1186/1753-6561-5-S9-S71
*  "Propensity score based methods for estimating the treatment effects ba" by Younathan Abdia
This dissertation consists of two interconnected research projects. The first project was a study of propensity scores based statistical methods for estimating the average treatment effect (ATE) and the average treatment effect among treated (ATT) when there are two treatment groups. The ATE is defined as the mean of the individual causal effects in the whole population, while ATT is defined as the treatment effect for the treated population. Propensity score based statistical methods, such as matching, regression, stratification, inverse probability weighting (IPW), and doubly robust (DR) methods were used to estimate the ATE and ATT. Simulation studies and case studies were conducted to examine the performances of propensity score based methods when propensity score was estimated using logistic regression and generalized boosted models (GBM). The aim of the second project ...
http://ir.library.louisville.edu/etd/2504/
*  Lecture 10b: More Examples of Propensity Score Adjustment - Module 4: Additional Topics in Regression | Coursera
Video created by Johns Hopkins University for the course 'Statistical Reasoning for Public Health 2: Regression Methods'. 2000+ courses from schools like Stanford and Yale - no application required. Build career skills in data science, computer ...
https://www.coursera.org/learn/statistical-reasoning-2/lecture/9WRs1/lecture-10b-more-examples-of-propensity-score-adjustment
*  Most recent papers with the keyword "Propensity score" statin | Read by QxMD
The use of retrospective healthcare claims datasets is frequently criticized for the lack of complete information on potential confounders. Utilizing patient's health status-related information from claims datasets as surrogates or proxies for mismeasured and unobserved confounders, the high-dimensional propensity score algorithm enables us to reduce bias. Using a previously published cohort study of post-myocardial infarction statin use (1998 - 2012), we compare the performance of the algorithm with a number of popular machine learning approaches for confounder selection in high-dimensional covariate spaces: random forest, least absolute shrinkage and selection operator, and elastic net ...
https://www.readbyqxmd.com/keyword/105240
*  Increased Stroke Risk among Patients with Open-Angle Glaucoma: A 10-Year Follow-up Cohort Study | IOVS | ARVO Journals
Purpose : Although several studies showed the correlation between the stroke and open angle glaucoma (OAG), there have not been enough large population based longitudinal studies. In this study, we investigated the risk of subsequent stroke development after initial OAG diagnosis over a 10-year follow-up period. Methods : We performed a retrospective nationwide propensity score-matched cohort study. OAG and comparison groups were selected from a large database from the Korean National Health Insurance Service, comprising 1,025,340 random subjects. The OAG group comprised patients with an initial diagnosis of OAG between January 2004 and December 2007 (n = 1,520), and the comparison group comprised randomly selected patients (five per glaucoma patient; n = 7,570). Patients who were diagnosed with stroke before the enrollment date were excluded. Each cohort was tracked until 2013 for stroke development. Cox proportional hazard regression analysis was performed to determine ...
http://iovs.arvojournals.org/article.aspx?articleid=2561028
*  Propensity scores
Propensity score gives the probability of a subject in a population to belong to a group of interest such as a treatment group. Then comparing subjects with the same propensity scores across treatment and no-treatment groups enables the researcher to infer on the effect of the treatment regarding a given outcome even if he works…
https://philippehavinh.wordpress.com/2014/07/25/propensity-scores/
*  ALCOHOL REPORTS: Effects of admission and treatment strategies of DWI courts on offender outcomes
The study used data from 8 DWI courts, 7 from Michigan and 1 from North Carolina. Using a 2-way classification system based on court casemix severity and program intensity, we selected participants in 1 of the courts, and alternatively 2 courts as reference groups. Reference group courts had relatively severe casemixes and high service intensity. We used propensity score matching to match participants in the other courts to participants in the reference group court programs. Program outcome measures were the probabilities of participants': failing to complete the court's program; increasing educational attainment; participants improving employment from time of program enrollment; and re-arrest. ...
http://alcoholreports.blogspot.com/2013/03/effects-of-admission-and-treatment.html
*  Increased risk of vascular disease associated with gout: A retrospective, matched cohort study in the UK Clinical Practice...
Objective To compare the effectiveness, safety and costs of standard versus individually tailored reduced doses of anti-tumour necrosis factor (TNF) drugs in patients with ankylosing spondylitis (AS) after achieving low-disease activity. Methods This was a single-centre prospective observational study performed within the ATTRA registry. The anti-TNF dose tapering strategy was chosen by treating physicians, without prespecified protocol. We used propensity score (PS) methodology to identify two cohorts of patients matched for relevant baseline characteristics who were treated with either reduced (n=53) or standard (n=83) doses of TNF inhibitors. One-year outcomes and costs of anti-TNF drugs were compared between both PS-matched cohorts. Results In the reduced dosing group, the median dose of TNF inhibitor corresponded to 0.67 and 0.5 of the standard dose initially and at 12 months respectively, and 21% of patients required return to standard dosing regimen. The mean change ...
https://www.phc.ox.ac.uk/publications/483682
*  Plus it
Our study had several methodological strengths, including the matching process of villages across the implementation boundaries. While we used propensity score matching using census data from several years before the study, we found that the villages matched well on multiple observed dimensions not used in the matching process, suggesting that the villages were matched on unobserved variables as well. We also focused on health outcomes proximal to the services covered by the scheme, as its circumscribed set of covered services enabled measurement of changes in cause specific mortality even if changes in general population health were difficult to measure.. This study was, however, also limited in several ways. First, it was quasi-experimental in that the scheme was not randomly assigned to villages. This posed several methodological challenges but also presented opportunities for using rigorous approaches designed to reduce selection bias. The northern portion of Karnataka ...
http://www.bmj.com/content/349/bmj.g5114
*  Impacto do Programa Bolsa Família no estado nutricional de crianças e adolescentes de duas regiões brasileiras
DISCUSSION. The results indicated that the PBF had a positive impact on the nutritional status of children and adolescents aged 5 to 19 years in both study regions. In the Northeast the beneficiary families had a smaller proportion of underweight children and adolescents, and in the Southeast, they had a smaller proportion of overweight/obese children and adolescents. These results, especially those that regard the Northeast, rectify the appropriate focus of the program as this region concentrates the country's highest prevalence of food insecurity [10]. Families that live in food insecurity may have difficulties to access adequate and healthy food, which may contribute to unfavorable nutritional diagnoses, such as malnutrition, for example. Assessment of public policies provides scientific evidence for political decision making. However, impact assessment studies must use the appropriate methodology, especially regarding sampling and confounder control. The present study used propensity ...
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-52732017000400477&lng=pt&nrm=iso&tlng=en
*  Comparison of "Risk-Adjusted" Hospital Outcomes | Circulation
We first estimated a propensity score model in which the dependent variable was multinomial, assuming 13 distinct values corresponding to the 13 hospitals (1 hospital is the reference group). The specific clinical variables included in the model were selected from a literature review of existing models and expert opinion from a panel of senior cardiac surgeons. A multinomial logistic regression model was estimated, and predictions for each patient in the sample were subsequently obtained. Thus, each patient had 14 estimated probabilities, each reflecting the likelihood that the patient would undergo CABG at 1 specific hospital rather than 1 of the remaining 13 hospitals. For this reason, the sum of the 14 estimated probabilities for each patient was 1.. To compare the performance of each hospital with that of its peers, it is necessary to assess whether the population of patients undergoing surgery at a particular hospital is comparable to that of all other Massachusetts ...
http://circ.ahajournals.org/content/117/15/1955
*  Clinics - vol.68 issue4
Effect of intraoperative HES 6% 130/0.4 on the need for blood transfusion after major oncologic surgery: a propensity-matched analysis ...
http://www.scielo.br/scielo.php?script=sci_issuetoc&pid=1807-593220130004&lng=en&nrm=iso
*  Patent US20080109445 - Systems and methods of enhancing leads - Google Patents
A client transmits one or more lead records to a lead enhancement module that is configured to enhance the received lead records and return enhanced lead records to the client. The lead enhancement module may return a contactability score for each lead record, indicating a likelihood that the individual identified in the lead may be contacted using the contact information provided in the lead record and/or additional contract information located by the lead enhancement module. The lead enhancement module may also receive additional data items associated with leads from one or more data sources. Additionally, statistical models that may be customized for each client may be applied to information associated with lead records in order to determine one or more propensity scores for each of the lead records, where a propensity score indicates a likelihood that an individual will take a particular action, such as purchasing ...
http://www.google.co.uk/patents/US20080109445
*  This supplementary material has been provided by the authors to give readers additional information about their work. - PDF
SUPPLEMENTAL MATERIAL Table S1. The logistic regression model used to calculate the propensity score. Table S2. Distribution of propensity score among the treat and control groups of the full and matched
http://docplayer.net/23820031-This-supplementary-material-has-been-provided-by-the-authors-to-give-readers-additional-information-about-their-work.html
*  Optimal Propensity Score Matching, Part 2 of 2 | Children and Family Futures
Sponsored by Children's Bureau, Office on Child Abuse and Neglect.. Tuesday, September 7, 2010 10:00 AM - 11:30 AM PST (1:00 PM - 2:30 PM EST). To learn more about this webinar, please contact Hanh Dao at hdao@cffutures.org. ...
http://www.cffutures.org/webinars/webinar-optimal-propensity-score-matching
*  Overview of Propensity Score Matching, Part 1 of 2 | Children and Family Futures
Sponsored by Children's Bureau, Office on Child Abuse and Neglect.. Wednesday, September 1, 2010 10:00 AM - 11:30 AM PST (1:00 PM - 2:30 PM EST). To learn more about this webinar, please contact Hanh Dao at hdao@cffutures.org.. ...
http://www.cffutures.org/webinars/webinar-overview-propensity-score-matching
*  Caduet in an Untreated Subject Population - Full Text View - ClinicalTrials.gov
Subjects who were recently diagnosed with both hypertension and dyslipidemia and who are not yet taking any medications for these conditions OR subjects with both hypertension and dyslipidemia who were previously treated with antihypertensive and/or lipid lowering medications but discontinued these medications for at least 3 months prior to the Screening visit ...
https://clinicaltrials.gov/ct2/show/NCT00332761
*  New heart disease risk score will help minimize health in...( A new score for predicting the risk of...)
Health,...A new score for predicting the risk of heart disease gives a more accu...The study published on bmj.com on July 6 estimates that in the gener...The study comes as the governments drugs watchdog the National Instit...A persons chance of developing heart disease is estimated using standa...,New,heart,disease,risk,score,will,help,minimize,health,inequalities,medicine,medical news today,latest medical news,medical newsletters,current medical news,latest medicine news
http://news.bio-medicine.org/medicine-news-3/New-heart-disease-risk-score-will-help-minimize-health-inequalities-224-1/
*  Software | GARY KING
MatchingFrontier is an easy-to-use R Package for making optimal causal inferences from observational data. Despite their popularity, existing matching approaches leave researchers with two fundamental tensions. First, they are designed to maximize one metric (such as propensity score or Mahalanobis distance) but are judged against another for which they were not designed (such as L1 or differences in means). Second, they lack a principled solution to revealing the implicit bias-variance trade off: matching methods need to optimize with respect to both imbalance (between the treated and control groups) and the number of observations pruned, but existing approaches optimize with respect to only one; users then either ignore the other, or tweak it, usually suboptimally, by hand.. MatchingFrontier resolves both tensions by consolidating previous techniques into a single, optimal, and flexible approach. It calculates the matching solution with maximum balance for each possible ...
https://gking.harvard.edu/software?page=1
*  New Originlab GraphGallery
Q-Q plot using Normal distribution and the Benard Score method. Observed values are plotted on the X axis with expected values on the Y axis ...
https://www.originlab.com/www/products/MyGraphGallery.aspx?s=1&e=0&t=Q-Q%20Plot&k=probability%20distribution,Reference%20Line
*  Patent US7342581 - Method and apparatus for displaying 3-D state indicators - Google Patents
A method for presenting a user selected status of an object in a three dimensional graphic display is disclosed. The method includes the step of receiving a request to select a property of an object for display. The method further includes the step of displaying at least one property which may be displayed for the object. A selection of a property is received and the value of the selected property for the object is determined. The method further includes the step of generating a status indicator based on the value of the selected property. The status indicator is then displayed relative to the object. In a preferred embodiment, the form of the status indicator is automatically determined by the system. An apparatus for implementing the method is also disclosed.
http://www.google.co.uk/patents/US7342581
*  Need help on approach to physics education | Physics Forums - The Fusion of Science and Community
It's funny that you mention Randall D. Knight because I quite frankly think that his 'Physics for Scientists and Engineers' is really among the best science books I have ever read (not finished yet, but I'm working on it!). Granted he does drag it out a bit sometimes, but I'd rather have a book too thorough than a book too short and hasty; you can always glimpse through passages if you're sure that you got the idea, however you cannot with your imagination fill in segments of a textbook that is heavily concentrated. Several of my friends didn't like it, but I love the way he writes, the examples and approach to the whole thing. Now we just need those teaching concepts taken to the next level for more advanced stuff and more calculus and advanced mathematics. This is the only point where I really find the book a bit lacking, it's the absence of more advanced calculus. But it's already more than 1300 pages, so the idea for Knight would be to write a 'sequal' and take the whole thing to the next ...
https://www.physicsforums.com/threads/need-help-on-approach-to-physics-education.238159/