Efficacy of venlafaxine and placebo during long-term treatment of depression: a pooled analysis of relapse rates.

The objective of this analysis was to determine the efficacy of venlafaxine in comparison with that of placebo during long-term treatment. A pooled analysis of relapse rates in outpatients with major depression continuing long-term treatment (up to 12 months) after responding to short-term treatment (6 weeks) was performed combining the data from four randomized, double-blind, placebo-controlled clinical trials. Relapses were defined as two consecutive Clinical Global Impression (CGI) severity scores greater than 3 (mildly ill), as a CGI severity score greater than 3 at withdrawal regardless of the reason for withdrawal, or as withdrawal due to lack of efficacy. Data from 304 patients (185 venlafaxine, 119 placebo) well balanced for baseline characteristics were included in the pooled analysis. Percentages of patients completing the long-term phase were 38% venlafaxine and 26% placebo (p = 0.034). Cumulative relapse rates by 6 months of long-term treatment were 11% venlafaxine and 23% placebo (p = 0.019). Cumulative relapse curves for the venlafaxine and placebo groups over the 1-year long-term treatment differed significantly (p = 0.022). The results from this analysis indicate that long-term treatment with venlafaxine in patients with major depressive disorder is effective in maintaining the initial response compared with placebo and suggest that venlafaxine will be effective in the prevention of relapse.