Residual symptoms after remission of major depressive disorder with fluoxetine and risk of relapse.

Background: Many patients with major depressive disorder (MDD) who achieve full remission after antidepressant treatment still have residual depressive symptoms. In this study, we assess the type and frequency of residual symptoms and their relationship to subsequent depressive relapses after remission of major depression with fluoxetine.

Method: Five hundred seventy-six patients with MDD were openly treated with fluoxetine for 12 weeks. Those who responded underwent random assignment, under double-blind conditions, to continue taking fluoxetine or to switch to placebo for 52 weeks or until relapse. The presence of residual symptoms in patients who achieved remission at the end of the acute phase (N=203) was assessed using the 28-item Hamilton Depression Rating Scale. Survival analysis was used to examine the effect of residual symptoms on relapse in remitters.

Results: More than 90% of patients who met criteria for remission had at least one residual depressive symptom (median=4). The most common were sleep disturbances (insomnia 48.2%, hypersomnia 35.9%) and anxiety (52.7%). The most common individual symptom was middle insomnia (33.5%). No statistically or clinically significant differences in baseline variables were found between remitters with and without residual symptoms. The presence of residual symptoms, the presence of residual insomnia and the global number of residual symptoms did not predict relapse during the continuation phase of the study.

Conclusion: The great majority of patients with remission of MDD after treatment with fluoxetine continue to experience selected residual depressive symptoms. The presence of residual symptoms is not significantly associated with an increased risk of relapse.