The effect of pain on outcomes in a trial of duloxetine treatment of major depressive disorder

Background. Patients with major depressive disorder (MDD) frequently report one or more pain symptoms. To explore the relationship between improvement in pain symptoms and MDD treatment outcomes, we conducted a secondary analysis of an approximately 12-week, open label trial of duloxetine in MDD. The primary objective was to test the hypothesis that a greater reduction in pain was associated with a higher probability of MDD remission. Methods. Adults with DSM-IV MDD were enrolled in the study if they had a Hamilton Depression Scale (HAMD-17) total score of 15 or more and a Clinical Global Impression of Severity (CGI-S) score of 4 or more. The duloxetine dose of patients could be titrated on the basis of the degree of response within the range from 60 to 120 mg given QD, with 90 mg QD as an intermediate dose. Remission of major depressive disorder was defined as a HAMD-17 total score of < 7. Core emotional symptoms of depression were determined by the HAMD-17 Maier subscale. Pain was assessed using a 100 mm visual analog scale (VAS) of overall pain severity over the last week (0 = no pain, 100 = pain as severe as I can imagine). For the primary analysis, mean change in VAS overall pain score over time was compared between remitters and non-remitters at endpoint using a mixed model repeated measures approach. Results. Two hundred forty nine patients were included in the analysis. A greater reduction in pain was associated with a significantly higher probability of remission of MDD, after accounting for changes in the core emotional symptoms. Greater pain reduction was associated with significant improvement in MDD core emotional symptoms. A greater improvement in pain was also associated with improvements in patient and clinician-rated global assessments. Conclusions. The effective treatment of pain symptoms in patients with major depressive disorder was associated with higher remission rates. The results underscore the importance of effectively treating painful symptoms associated with depression.