Purpose: To assess the efficacy of fluoxetine in the treatment of patients with fibromyalgia.
Subjects and methods: Sixty outpatients (all women, aged 21-71 years) with fibromyalgia were randomly assigned to receive fluoxetine (10-80 mg/d) or placebo for 12 weeks in a double-blind, parallel-group, flexible-dose study. The primary outcome measures were the Fibromyalgia Impact Questionnaire total score (score range, 0 [no impact] to 80) and pain score (score range, 0-10). Secondary measures included the McGill Pain Questionnaire, change in the number of tender points, and total myalgic score.
Results: In the intent-to-treat analysis, women who received fluoxetine (mean [+/- SD] dose, 45 +/- 25 mg/d) had significant (P = 0.005) improvement in the Fibromyalgia Impact Questionnaire total score compared with those who received placebo, with a difference of -12 (95% confidence interval [CI]: -19 to -4). They also had significant (P = 0.002) improvement in the Fibromyalgia Impact Questionnaire pain score (difference, -2.2 [95% CI: -3.6 to -0.9]), as well as in the Fibromyalgia Impact Questionnaire fatigue (P = 0.05) and depression (P = 0.01) scores and the McGill Pain Questionnaire (P = 0.01), when compared with subjects who received placebo. Although counts for the number of tender points and total myalgic scores improved more in the fluoxetine group than in the placebo group, these differences were not statistically significant.
Conclusions: In a 12-week, flexible-dose, placebo-controlled trial, fluoxetine was found to be effective on most outcome measures and generally well tolerated in women with fibromyalgia.