The persistence of the placebo response in antidepressant clinical trials.

Our objective was to assess the persistence of the placebo response during at least 12 weeks of continued placebo administration in depressed patients who have responded to 6-8 weeks of acute placebo treatment. We identified 8 placebo-controlled antidepressant trials with a total of 3,063 depressed patients in which, after acute phase placebo treatment, placebo was continued for more than 12 weeks. The number of patients entering the continuation phase and percentages relapsing during this phase were determined. Based on the total number of patients entering the continuation phase 79% of placebo responders remained well (did not meet relapse criteria) during this phase compared to 93% of antidepressant responders. Although significantly more patients on placebo than on antidepressants relapsed in the continuation phase, 4 out of 5 placebo responders stayed well. The widely held belief that the placebo response in depression is short-lived appears to be based largely on intuition and perhaps wishful thinking.