Efficacy of duloxetine in patients with fibromyalgia: pooled analysis of 4 placebo-controlled clinical trials.

OBJECTIVE

To investigate the efficacy of duloxetine in the treatment of pain and improvement in functional impairment and quality of life in patients with fibromyalgia from a pooled analysis of 4 placebo-controlled, double-blind, randomized trials.

METHOD

Patients were eligible for inclusion in the studies if they were at least 18 years of age, met criteria for fibromyalgia as defined by the American College of Rheumatology, and had specified minimum pain severity scores. Across all studies, 797 patients received duloxetine 60-120 mg/d and 535 patients received placebo. Pain was assessed by the Brief Pain Inventory (BPI) 24-hour average pain severity score; other efficacy measures included the Clinical Global Impressions-Severity of Illness scale (CGI-S), Patient Global Impressions-Improvement scale (PGI-I), 17-item Hamilton Depression Rating Scale (HDRS-17), Fibromyalgia Impact Questionnaire (FIQ) total score, BPI pain interference items, Sheehan Disability Scale (SDS), and Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) mental and physical components. Changes from baseline to endpoint (last observation carried forward) for most of the above efficacy measures were analyzed using an analysis-of-covariance model.

RESULTS

After 12 weeks of treatment, pain was significantly reduced in patients treated with duloxetine (P < .001) compared with placebo. In addition, duloxetine was superior to placebo in improving CGI-S (P < .001); PGI-I (P < .001); FIQ total (P < .001); HDRS-17 total (P = .003); SDS global functioning (P < .001), work/school (P = .018), and family life (P < .001); SF-36 mental (P < .001) and physical (P = .026) component; and BPI pain interference (P < .001) scores. Treatment-by-subgroup interactions were not significant for sex (P = .320), age (P = .362), or race (P = .180).

CONCLUSIONS

This pooled analysis provides evidence that 12 weeks of treatment with duloxetine 60-120 mg/d effectively improves fibromyalgia symptoms and may offer benefits beyond pain relief.