Background: Despite of a high comorbidity of depressive and/or anxiety disorders with fibromyalgia, information on the clinical implications of this comorbidity is limited but antidepressants are commonly prescribed to treat fibromyalgia in clinical practice. We investigated whether a history of depressive and/or anxiety disorders was associated with response to paroxetine controlled release (CR) in the treatment of fibromyalgia.
Methods: One hundred sixteen (116) fibromyalgia subjects were randomized to receive paroxetine CR or placebo for 12 weeks. The primary outcome was treatment response defined as >or=25% reduction in the Fibromyalgia Impact Questionnaire (FIQ) score. In multivariate logistic regression, we determined if a history of depression and/or anxiety disorders was an independent predictor of response to paroxetine CR.
Results: In logistic regression, the history of depression and/or anxiety did not predict treatment response as measured by >or=25% reduction in Fibromyalgia Impact Questionnaire (FIQ) score (OR=0.66, 95% CI=.29-1.49, Wald=0.97, p=0.32), while the drug status (paroxetine CR) was significantly associated with treatment response (OR=2.57, CI=1.2-5.61, Wald=5.5, p=0.02).
Conclusion: A significant proportion of patients with fibromyalgia had a history of anxiety and or depressive disorders. However response to treatment of fibromyalgia symptoms with paroxetine CR was not associated with a history of depressive and/or anxiety disorders. Our findings need to be confirmed in more adequately-powered and well-designed subsequent studies.