Clinical trials of antidepressants: "enrichment strategies".

To the Editor: I read with great interest the article by Merlo-Pich and colleagues titled “A New Population-Enrichment Strategy to Improve Efficiency of Placebo-Controlled Clinical Trials of Antidepressant Drugs.”1 Because one in two clinical trials of US Food and Drug Administration–approved antidepressants fails,2 the authors suggest that the efficiency and accuracy of studies should be improved to reduce the frequency of failed and uninformative trials. They further propose that the exclusion of data from sites showing extremely high or extremely low placebo effects may help to achieve this goal. After the authors applied a post hoc enrichment-window model, the probability of a successful antidepressant trial increased from 50% to 90%. I respectfully disagree with the premise of this article. Instead, I argue that, in order for antidepressant trials to demonstrate greater benefit, the efficacy of the drug itself should be “enriched,” thereby avoiding the need for data manipulation and cherry picking to arrive at a biased conclusion. The article is particularly concerning because three of the four authors clearly have a vested interest in the success of these trials. We would all do well to remember that the goal of clinical trials is to arrive at the truth, not necessarily to achieve success.