History of depressive and/or anxiety disorders as a predictor of treatment response: A post hoc analysis of a 12-week, randomized, double-blind, placebo-controlled trial of paroxetine controlled release in patients with fibromyalgia

BackgroundDespite 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.MethodsOne hundred sixteen (116) fibromyalgia subjects were randomized to receive paroxetine CR or placebo for 12 weeks. The primary outcome was treatment response defined as ≥ 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.ResultsIn logistic regression, the history of depression and/or anxiety did not predict treatment response as measured by ≥ 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).ConclusionA 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.