Relative antidepressant efficacy of venlafaxine and SSRIs: Sex-age interactions

Objective: To investigate whether differences in antidepressant efficacy are moderated by an interaction of age and gender. Methods: A pooled dataset from eight randomized, controlled trials of patients with major depressive disorder (MDD) was reanalyzed to compare remission rates following therapy with venlafaxine (n = 851), one of several selective serotonin reuptake inhibitors (SSRIs) (n = 748), or placebo (n = 446). Remission was defined as a final Hamilton Rating Scale for Depression (HAM-D) score <= 7. Pairwise comparisons were conducted using stepwise multiple logistic regression models with main effect and interaction terms for treatment, sex, and age (younger: < 50; older: >= 50). Among older women, the impact of hormone replacement therapy (HRT) on remission rates also was examined. Results: Remission rates on venlafaxine therapy were not affected by age, sex, or HRT use. Among women, but not men, there was a significant interaction reflecting poorer SSRI response in the older age group (Wald chi-square = 4.21, df = 1, p = 0.04); HRT appeared to eliminate this difference. Whereas the advantage in remission rates favoring venlafaxine was modest for men and younger women (6% - 9%), the difference among older women not taking HRT was 23%. Conclusions: These findings provide further evidence that age, gender, and HRT moderate response to antidepressant medications.