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

To investigate whether differences in antidepressant efficacy are moderated by an interaction of age and gender.

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 < or =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: > or =50). Among older women, the impact of hormone replacement therapy (HRT) on remission rates also was examined.

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%.

These findings provide further evidence that age, gender, and HRT moderate response to antidepressant medications.