Has the rising placebo response impacted antidepressant clinical trial outcome? Data from the US Food and Drug Administration 1987‐2013

• Published in: World psychiatry 2017-06, Vol.16 (2), p.181-192
• Main Authors: Khan, Arif, Fahl Mar, Kaysee, Faucett, Jim, Khan Schilling, Shirin, Brown, Walter A.
• Format: Article
• Language: English
• Subjects: Antidepressants; antidepressant‐placebo difference; Clinical trials; effect size; enhanced interview techniques; Placebo effect; placebo response; Research Report; Research Reports; Studies; success rate
• ISSN: 1723-8617; 2051-5545
• DOI: 10.1002/wps.20421

More than fifteen years ago, it was noted that the failure rate of antidepressant clinical trials was high, and such negative outcomes were thought to be related to the increasing magnitude of placebo response. However, there is considerable debate regarding this phenomenon and its relationship to outcomes in more recent antidepressant clinical trials. To investigate this, we accessed the US Food and Drug Administration (FDA) reviews for sixteen antidepressants (85 trials, 115 trial arms, 23,109 patients) approved between 1987 and 2013. We calculated the magnitude of placebo and antidepressant responses, antidepressant‐placebo differences, as well as the effect sizes and success rates, and compared these measures over time. Exploratory analysis investigated potential changes in trial design and conduct over time. As expected, the magnitude of placebo response has steadily grown in the past 30 years, increasing since 2000 by 6.4% (r=0.46, p