Efficacy of antidepressants

In February 2008, Kirsch and colleagues reported a meta-analysis of the efficacy of antidepressants using data from clinical trials submitted to the Food and Drug Administration.1 They provocatively concluded, “there seems little evidence to support the prescription of antidepressant medication to any but the most severely depressed patients.”

In January this year, we published an article about the selective publication of antidepressant trials and its influence on apparent efficacy,2 in which we also used FDA data. Our main finding was that antidepressant drugs are much less effective than is apparent from journal articles. From the FDA data we derived an overall effect size of 0.31. Kirsch and colleagues used FDA data from four of the 12 drugs we examined and calculated an overall effect size of 0.32.

Although these two sets of results were in excellent agreement, our interpretations of them were quite different. In contrast to Kirsch and colleagues’ conclusion that antidepressants are ineffective, we concluded that each drug was superior to placebo. The difference in our interpretations stems from …