title: Assessing apparent treatment--covariate interactions in randomized clinical trials.
abstract: In the context of clinical trials, a qualitative treatment--covariate interaction occurs when a patient's preferred treatment depends on his covariates. In this paper I review the nature and interpretation of various kinds of interactions, compare the use of overall tests for interaction to subset analysis, present some examples of apparent treatment-covariate interactions that have arisen in actual randomized clinical trials, and discuss some recent work by others related to significance testing, estimation and assessment of apparent treatment-covariate interactions.
mesh_terms: D000704:Analysis of Variance; D002986:Clinical Trials as Topic / Q000379:methods*; D004054:Diethylstilbestrol / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology; D011897:Random Allocation; D012107:Research Design
chemical_list: D004054:Diethylstilbestrol