title: Performance of informative priors skeptical of large treatment effects in clinical trials: A simulation study.
abstract: One of the main advantages of Bayesian analyses of clinical trials is their ability to formally incorporate skepticism about large treatment effects through the use of informative priors. We conducted a simulation study to assess the performance of informative normal, Student- t, and beta distributions in estimating relative risk (RR) or odds ratio (OR) for binary outcomes. Simulation scenarios varied the prior standard deviation (SD; level of skepticism of large treatment effects), outcome rate in the control group, true treatment effect, and sample size. We compared the priors with regards to bias, mean squared error (MSE), and coverage of 95% credible intervals. Simulation results show that the prior SD influenced the posterior to a greater degree than the particular distributional form of the prior. For RR, priors with a 95% interval of 0.50-2.0 performed well in terms of bias, MSE, and coverage under most scenarios. For OR, priors with a wider 95% interval of 0.23-4.35 had good performance. We recommend the use of informative priors that exclude implausibly large treatment effects in analyses of clinical trials, particularly for major outcomes such as mortality.
authors.affiliation: Center for Clinical Research and Evidence-Based Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Pedroza
authors.affiliation: Center for Clinical Research and Evidence-Based Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.
authors.forename: Weilu
authors.initials: W
authors.lastname: Han
authors.affiliation: Center for Clinical Research and Evidence-Based Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.
authors.forename: Van Thi Thanh
authors.initials: VTT
authors.lastname: Truong
authors.affiliation: Center for Clinical Research and Evidence-Based Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Green
authors.affiliation: Center for Clinical Research and Evidence-Based Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.
authors.forename: Jon E
authors.initials: JE
authors.lastname: Tyson
mesh_terms: D001499:Bayes Theorem; D015982:Bias; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data; D003198:Computer Simulation; D015233:Models, Statistical; D012044:Regression Analysis; D016896:Treatment Outcome
keywords: Bayesian analysis; binary data; clinical trial; informative priors; large treatment effects; robust priors