Factors predicting reduced antidepressant response: Experience with the SNRI duloxetine in patients with major depression

Background: To identify putative demographic and clinical variables that correlate with antidepressant response to the SNRI duloxetine in major depression. Methods: The effect of 130 candidate treatment outcome predictors was examined on 3 dependent treatment outcome measures related to depression: 1) depression symptom outcome measured by HAMD-17 total and HAMD-17 percent change from baseline to endpoint, 2) remission (HAMD-17 ≤ 7 at endpoint) and response (≥ 50% reduction in HAMD-17 from baseline to endpoint) rates, and 3) time to response (days to ≥ 50% reduction in HAMD-17). Results: Eleven variables had an overall predictive index of ≥ 20% and were associated with poorer treatment outcome: HAMD-17 total, duration of current MDD episode, leaden paralysis, fatigue, HAMA total, HAMA items 2 and 8, HAMD-17 anxiety/somatization subscale, anxiety-related comorbid conditions, and VAS overall pain and pain while awake. Conclusions: Our results highlight the clinical relevance of more severe and/or persistent levels of depression, psychiatric and medical comorbidity, and symptoms characteristic of atypical depression (leaden paralysis and fatigue) and confirm findings from other studies that such patients may respond less well or take longer to respond to pharmacotherapy. Consistent with previous SNRI studies, we found no significant association between age, gender, and race/ethnicity and treatment outcome.