Fibromyalgia is a chronic disorder that affects approximately 3.4% of women and 0.5% of men in the United States. It is characterized as widespread musculoskeletal pain, fatigue, and a reduced threshold for pain. Treatment can be complicated by the comorbid depressive moods that often accompany fibromyalgia. Three double-blind, placebo-controlled studies examined the correlation between treatment effect on pain and levels of depression/anxiety in fibromyalgia patients.

Arnold L et al. (NR7–090) presented pooled data from 3 trials that compared pregabalin 150, 300, 450, and 600 mg/day with placebo after 8–14 weeks of treatment in >1500 fibromyalgia patients. Significant (p<0.001) reductions in pain (≥30% reduction on the pain diary score) with 450 and 600 mg/day doses of pregabalin were reported at the study endpoint. Significant changes, relative to baseline, were also seen on the Hospital Anxiety and Depression Scale (HADS) (450 and 600 mg doses; p<0.01), the Multidimensional Assessment of Fatigue (MAF), and the Patient Global Impression of Change (PGIC) (all p<0.05). Patients also reported significant (p<0.001) improvement in sleep quality (300–600 mg doses). Changes in pain relative to sleep and PGIC scores were highly correlated, pain and MAF were moderately correlated, while pain and HAD scores had little correlation. Adverse events occurring in greater frequency in pregabalin-treated patients were dizziness, somnolence, weight increase, blurred vision, and dry mouth.

Gendreau RM et al. (NR7–091) evaluated the impact of baseline depression severity on the efficacy of milnacipran (100 or 200 mg/day) as treatment for fibromyalgia in a 6-month study. Milnacipran (100 and 200 mg/day) significantly improved the composite score for pain (≥30% reduction on the pain diary score + PGIC score) at 3 (p<0.03) and 6 months (p<0.05). Maximum pain relief was achieved within 9 weeks of beginning treatment and was maintained for the duration of the study. Pain relief was independent of depression, as indicated by baseline Beck Depression Inventory scores. Mild to moderate nausea and headaches were commonly reported adverse events among all patients.

Arnold LM et al. (NR3–069) presented pooled data from 4 duloxetine (combined scores for 60 or 120 mg/day) studies in fibromyalgia patients with and without depression. Significant (p<0.05) improvement versus placebo was noted on the Brief Pain Inventory average score, the Fibromyalgia Impact Questionnaire, the clinician GI-S and patient GI-I scores in patients with and without comorbid depression beginning at Week 1. HAM-D17 scores showed significant improvement in depressed patients (−5.77 vs −4.39; p<0.05) who were treated with duloxetine versus placebo. Common adverse events included nausea, headache, constipation, and somnolence, which were significantly (p<0.05%) higher with duloxetine in both depressed and nondepressed patients.

All three drugs improved pain, patients' impression of change in their disease state, and their self-reported ability to function, regardless of their baseline depression score.