Association Between Bipolar Spectrum Features and Treatment Outcomes in Outpatients With Major Depressive Disorder

CONTEXT: It has been suggested that patients with major depressive disorder (MDD) who display pretreatment features suggestive of bipolar disorder or bipolar spectrum features might have poorer treatment outcomes. OBJECTIVE: To assess the association between bipolar spectrum features and antidepressant treatment outcome in MDD. DESIGN: Open treatment followed by sequential randomized controlled trials. SETTING: Primary and specialty psychiatric outpatient centers in the United States. PARTICIPANTS: Male and female outpatients aged 18 to 75 years with a DSM-IV diagnosis of nonpsychotic MDD who participated in the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study. INTERVENTIONS: Open treatment with citalopram followed by up to 3 sequential next-step treatments. MAIN OUTCOME MEASURES: Number of treatment levels required to reach protocol-defined remission, as well as failure to return for the postbaseline visit, loss to follow-up, and psychiatric adverse events. For this secondary analysis, putative bipolar spectrum features, including items on the mania and psychosis subscales of the Psychiatric Diagnosis Screening Questionnaire, were examined for association with treatment outcomes. RESULTS: Of the 4041 subjects who entered the study, 1198 (30.0%) endorsed at least 1 item on the psychosis scale and 1524 (38.1%) described at least 1 recent maniclike/hypomaniclike symptom. Irritability and psychoticlike symptoms at entry were significantly associated with poorer outcomes across up to 4 treatment levels, as were shorter episodes and some neurovegetative symptoms of depression. However, other indicators of bipolar diathesis including recent maniclike symptoms and family history of bipolar disorder as well as summary measures of bipolar spectrum features were not associated with treatment resistance. CONCLUSION: Self-reported psychoticlike symptoms were common in a community sample of outpatients with MDD and strongly associated with poorer outcomes. Overall, the data do not support the hypothesis that unrecognized bipolar spectrum illness contributes substantially to antidepressant treatment resistance.