An observational study of duloxetine versus SSRI monotherapy for the treatment of painful physical symptoms in Japanese patients with major depressive disorder: primary analysis

OBJECTIVE The objective of this study was to assess the effectiveness of duloxetine monotherapy, in comparison with selective serotonin reuptake inhibitor (SSRI) monotherapy, in the treatment of painful physical symptoms (PPS) in Japanese patients with major depressive disorder (MDD) in real-world clinical settings. METHODS This was a multicenter, 12-week prospective, observational study. This study enrolled MDD patients with at least moderate PPS, defined as a Brief Pain Inventory-Short Form (BPI-SF) average pain score (item 5) ≥3. Patients were treated with duloxetine or SSRIs (escitalopram, sertraline, paroxetine, or fluvoxamine) for 12 weeks, and PPS were assessed by BPI-SF average pain score. The primary outcome was early improvement in the BPI-SF average pain score at 4 weeks post-baseline. RESULTS A total of 523 patients were evaluated for treatment effectiveness (duloxetine N=273, SSRIs N=250). The difference in BPI-SF average pain score between the two groups was not statistically significant at 4 weeks post-baseline, the primary endpoint (least-squares mean change from baseline [95% confidence interval]: duloxetine, -2.8 [-3.1, -2.6]; SSRIs, -2.5 [-2.8, -2.3]; P=0.166). There was a numerical advantage for duloxetine in improvement from 4 to 12 weeks post-baseline, and the difference was statistically significant at 8 weeks post-baseline (least-squares mean change from baseline [95% confidence interval]: duloxetine, -3.6 [-3.9, -3.3]; SSRIs, -3.1 [-3.4, -2.8]; P=0.023). The 30% and 50% responder rates were significantly higher in patients treated with duloxetine at 4 and 8 weeks post-baseline. There were no serious adverse events experienced by duloxetine-treated patients. The rate of discontinuations due to adverse events was similar for duloxetine and the SSRIs (1.0% and 0.8% of patients, respectively). CONCLUSION In this observational study, BPI-SF improvement was not significantly different at 4 weeks, the primary endpoint; however, patients treated with duloxetine tended to show better improvement in PPS compared to those treated with SSRIs.