title: A Bayesian sensitivity model for intention-to-treat analysis on binary outcomes with dropouts.
abstract: Intention-to-treat (ITT) analysis is commonly used in randomized clinical trials. However, the use of ITT analysis presents a challenge: how to deal with subjects who drop out. Here we focus on randomized trials where the primary outcome is a binary endpoint. Several approaches are available for including the dropout subject in the ITT analysis, mainly chosen prior to unblinding the study. These approaches reduce the potential bias due to breaking the randomization code. However, the validity of the results will highly depend on untestable assumptions about the dropout mechanism. Thus, it is important to evaluate the sensitivity of the results across different missing-data mechanisms. We propose here a Bayesian pattern-mixture model for ITT analysis of binary outcomes with dropouts that applies over different types of missing-data mechanisms. We introduce a new parameterization to identify the model, which is then used for sensitivity analysis. The parameterization is defined as the odds ratio of having an endpoint between the subjects who dropped out and those who completed the study. Such parameterization is intuitive and easy to use in sensitivity analysis; it also incorporates most of the available methods as special cases. The model is applied to TRial Of Preventing HYpertension.
authors.affiliation: Center for Human Growth and Development, University of Michigan, Ann Arbor, MI 48109, USA. nicola@umich.edu
authors.forename: Niko A
authors.initials: NA
authors.lastname: Kaciroti
authors.forename: M Anthony
authors.initials: MA
authors.lastname: Schork
authors.forename: Trivellore
authors.initials: T
authors.lastname: Raghunathan
authors.forename: Stevo
authors.initials: S
authors.lastname: Julius
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage; D001499:Bayes Theorem; D001562:Benzimidazoles / Q000008:administration & dosage; D015982:Bias; D001713:Biphenyl Compounds; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000517:prevention & control; D016015:Logistic Models; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D016017:Odds Ratio; D010352:Patient Dropouts / Q000706:statistics & numerical data*; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012680:Sensitivity and Specificity; D013777:Tetrazoles / Q000008:administration & dosage
chemical_list: D000959:Antihypertensive Agents; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D013777:Tetrazoles; C081643:candesartan