Regenstrief Institute

About: Regenstrief Institute is a nonprofit organization based out in Indianapolis, Indiana, United States. It is known for research contribution in the topics: Health care & Population. The organization has 742 authors who have published 2042 publications receiving 96966 citations.

Simultaneous variable selection for joint models of longitudinal and survival outcomes

Abstract: Joint models of longitudinal and survival outcomes have been used with increasing frequency in clinical investigations. Correct specification of fixed and random effects is essential for practical data analysis. Simultaneous selection of variables in both longitudinal and survival components functions as a necessary safeguard against model misspecification. However, variable selection in such models has not been studied. No existing computational tools, to the best of our knowledge, have been made available to practitioners. In this article, we describe a penalized likelihood method with adaptive least absolute shrinkage and selection operator (ALASSO) penalty functions for simultaneous selection of fixed and random effects in joint models. To perform selection in variance components of random effects, we reparameterize the variance components using a Cholesky decomposition; in doing so, a penalty function of group shrinkage is introduced. To reduce the estimation bias resulted from penalization, we propose a two-stage selection procedure in which the magnitude of the bias is ameliorated in the second stage. The penalized likelihood is approximated by Gaussian quadrature and optimized by an EM algorithm. Simulation study showed excellent selection results in the first stage and small estimation biases in the second stage. To illustrate, we analyzed a longitudinally observed clinical marker and patient survival in a cohort of patients with heart failure.

Sensible use of observational clinical data.

Abstract: Observational data sets offer many potential advantages for medical research including their low cost, large size and generalisability. Because they are collected for clinical care and health care operations purposes, observational data sets have some limitations that must be considered in order to perform useful analyses. Sensible use of observational data sets can yield valuable insights, particularly when clinical trials are impractical.

To what extent do educational interventions impact medical trainees' attitudes and behaviors regarding industry-trainee and industry-physician relationships?

Abstract: BACKGROUND. Recently, academic medical centers have been asked to take the lead in voluntarily instituting more stringent regulations regarding pharmaceutical industry interactions not only with physicians but also with medical trainees. OBJECTIVE. Our goal was to summarize the recent literature regarding the impact of educational interventions and regulatory policies on trainee perceptions of pharmaceutical industry interactions and/or pharmaceutical industry–related trainee behavior. METHODS. We searched Medline and the bibliographies of review articles for relevant studies. Articles published before the Accreditation Council for Continuing Medical Education standards for commercial support of continuing medical education were issued in 1991 were excluded. Two reviewers selected empiric studies that (1) reported empiric data about educational interventions that were meant to shape trainee knowledge, attitudes, or practices concerning the pharmaceutical industry or (2) evaluated the impact of regulatory policies on trainee attitudes or behaviors. RESULTS. From 247 identified articles, 12 met the inclusion criteria. In 2 of these studies, the impact of regulatory policies on trainee attitudes and/or behaviors was assessed. In the remaining 10 studies, the impact of various educational interventions developed by training programs or schools to shape trainee knowledge, attitudes, or practices concerning the pharmaceutical industry were evaluated. CONCLUSIONS. Although modest in size, a body of empirical research exists that might inform medical educators. Beyond institutional policy that excludes the pharmaceutical industry, the evidence reviewed suggests that well-designed seminars, role playing, and focused curricula can affect trainee attitudes and behavior, although it is not entirely clear whether these changes are sustainable over the long-term.