Predicting treatment outcomes of major depressive disorder by early improvement in painful physical symptoms: a pooled analysis of double-blind, placebo-controlled trials of duloxetine

OBJECTIVE: We determined if early improvement in painful physical symptoms (PPS) can be a predictor of remission in the treatment of major depressive disorder (MDD). METHODS: We included randomized, double-blind, parallel-group clinical trials of duloxetine (40–60 mg/day) versus placebo for the acute treatment of MDD with associated PPS. Only those studies using the Montgomery–Åsberg Depression Rating Scale (MADRS) and the Brief Pain Inventory – Short Form (BPI-SF) were included. Three studies met all criteria and included male or female outpatients aged ≥18 years who met the diagnostic criteria for MDD, had a MADRS total score ≥20, and had at least moderate pain (BPI-SF average pain score ≥3). Positive predictive values (PPVs) and negative predictive values (NPVs) of early improvement in PPS for remission were analyzed. PPVs were the proportion of patients with remission (MADRS total score ≤10) at week 8 out of patients who experienced early improvement in BPI-SF average pain score (≥30% decrease from baseline at week 1, 2, or 4). NPVs were the proportion of patients without remission (MADRS total score >10) at week 8 out of patients who did not experience early improvement in PPS. RESULTS: Data from 1,320 patients were analyzed (duloxetine N=641 and placebo N=679). The overall remission (MADRS total score ≤10 at week 8) rate for the duloxetine group was significantly higher than the placebo group (38.5% vs 21.8%; P<0.0001). For both treatment groups, PPVs of early improvement in BPI-SF (30% improvement from baseline) were higher than the overall remission rate for all weeks examined (weeks 1, 2, and 4); in general, NPVs of early improvement in BPI-SF for nonremission were higher than the overall nonremission rate. CONCLUSION: Early improvement in PPS can be a useful clinical indicator of subsequent treatment outcome for MDD patients with associated PPS.