Relationship between probability of receiving placebo and probability of prematurely discontinuing treatment in double-blind, randomized clinical trials for MDD: a meta-analysis.

An increased likelihood of receiving placebo in randomized clinical trials has been found to predict greater chances of trial success. However, patients who are less likely to receive active therapy (and more likely to receive placebo) may be at increased risk of attrition which, in turn, can limit the statistical power of a study. Therefore, in the present work, we sought to investigate the relationship between the probability of receiving placebo and the likelihood of prematurely discontinuing treatment. Medline/Pubmed publication databases were searched for RCT in MDD. A meta-regression established that the likelihood of receiving placebo did not predict either antidepressant discontinuation rates, placebo-discontinuation rates or the risk ratio of discontinuing antidepressants versus placebo. An increased likelihood of receiving placebo did not inflate discontinuation rates which did not influence the degree of antidepressant-placebo "separation". Copyright 2010 Elsevier B.V. and ECNP. All rights reserved.