title: A note on randomization and selection bias in maintenance therapy clinical trials.
abstract: In this article we demonstrate that even in randomized controlled clinical trials, unobserved confounding variables can bias the outcome of a study. For the case of a two-phase maintenance therapy trial where patients who respond to treatment during the acute phase are then randomized to a maintenance therapy, we show explicitly the role that confounding may play in biasing the interpretation of the results of such a trial. We suggest an alternative design to deal with the problem of a selection effect for treatment responders in the acute phase of the trial by randomizing patients at the outset of the study to both an acute and maintenance therapy.
authors.affiliation: Department of Statistics, Carnegie Mellon University, Pittsburgh, PA 15213.
authors.forename: J B
authors.initials: JB
authors.lastname: Greenhouse
authors.forename: M M
authors.initials: MM
authors.lastname: Meyer
mesh_terms: D015982:Bias; D004358:Drug Therapy; D006801:Humans; D011897:Random Allocation; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012107:Research Design