Effectiveness of Duloxetine Monotherapy Compared to Combination Therapy with Other Antidepressants in Patients with Major Depressive Disorder: A Short-Term, Retrospective Study

OBJECTIVE: The purpose of this study was to compare duloxetine monotherapy to combination therapy with other antidepressants in patients with major depressive disorder in a clinical, real world setting. METHODS: An eight-week, retrospective, multi-center study of outpatients with major depressive disorder was undertaken. After screening 415 patients, enrolled in this study from July 2009 to June 2014 were 82 patients from among three centers who had been taking duloxetine with or without other antidepressant and not administered with atypical antipsychotics. We compared the mean changes of the Clinical Global Impression-Severity Scale (CGI-S) as a primary measure and the discontinuation rate as a secondary measure between the duloxetine monotherapy group (n=36, 43.9%) and the combination therapy with other antidepressants group (n=46, 56.1%) at baseline, one, two, four and eight weeks. RESULTS: There were no significant differences across the demographic characteristics between two groups. There was, however, a statistically greater improvement on the CGI-S at weeks 2, 4 and 8 in the combination group compared with the monotherapy group. There were no significant differences in discontinuation rate and adverse events between two groups. No serious adverse events were reported in both groups during the study period. CONCLUSION: This result suggests that the duloxetine combination therapy with other antidepressants could improve effectiveness and have comparable tolerability with the monotherapy in the treatment of outpatients with major depressive disorders in a naturalistic setting. Adequately powered, well-controlled clinical trials are strongly warranted to confirm our findings due to methodological shortcomings.