Background: Antidepressants have unequivocal efficacy as compared with placebo, but many patients have residual symptoms despite a robust response to antidepressant therapy. The purpose of this study is to assess residual symptoms in outpatients who respond acutely to fluoxetine.
Method: Two hundred and fifteen outpatients with major depressive disorder as assessed with the Structured Clinical Interview for DSM-III-R (SCID-P) were treated openly with fluoxetine 20 mg/day for 8 weeks. One hundred and eight (50.2%) were considered full responders (final 17-item Hamilton Rating Scale for Depression [HAM-D] score < or =7). Percentages of full responders who continued to have subthreshold or full major depressive disorder symptoms were calculated. The relationship between residual symptoms and Axis I and Axis II (assessed with SCID-II for personality disorders) comorbidity was assessed.
Results: Of the 108 responders, 19 (17.6%) had no subthreshold or threshold SCID-P major depressive disorder symptoms, while 28 (25.9%) had 1 symptom, and 61 (56.5%) had 2 or more symptoms. No statistically significant relationships were found between number of residual symptoms and selected Axis I comorbid conditions or total number of Axis II disorders.
Conclusion: Less than 20% of full responders to fluoxetine by HAM-D criteria were free of all SCID-P subthreshold and threshold major depressive disorder symptoms after 8 weeks of treatment. While depressed patients benefit from antidepressants, most continue to have some symptoms of depression. The high prevalence of residual symptoms among antidepressant responders suggests the need for further study including whether residual symptoms abate with longer treatment or increased dose of fluoxetine. Other strategies, such as cognitive behavioral therapy, may be needed to address residual symptoms.