History of early abuse as a predictor of treatment response in patients with fibromyalgia: A post-hoc analysis of a 12-week, randomized, double-blind, placebo-controlled trial of paroxetine controlled release

Objectives. We conducted a post-hoc analysis to determine whether a history of physical or sexual abuse was associated with response to treatment in a double-blind, randomized, placebo-controlled trial of paroxetine controlled release (CR) in fibromyalgia. Methods. A randomized, double-blind, placebo-controlled trial of paroxetine controlled release (CR) (dose 12.562.5 mg/day) was conducted in patients with fibromyalgia for 12 weeks. A total of 112 subjects provided complete information on childhood history of abuse that was recorded using the Sexual and Physical Abuse Questionnaire and randomized to treatments. Outcome evaluations in the abuse subgroup were identical to those in the entire sample. Health Status was determined using the 36-Item Short Form Health Survey (SF-36), the Sheehan Disability Scale (SDS), and the Perceived Stress Scale (PSS). Fibromylagia symptom severity was determined using the Fibromyalgia Impact Questionnaire (FIQ) and the Visual Analogue Scale for Pain (VAS). The primary outcome was treatment response defined as ≥25% reduction in the FIQ-total score. Secondary outcomes include changes in scores on the Clinical Global Impression-Severity and Improvement (CGI-S and CGI-I respectively) and SF-36. Results. The rate of childhood physical and/or sexual abuse was 52.7% (n=59). The baseline characteristics (health status, perceived stress, symptom severity) were not associated with abuse history. In logistic regression, the history of abuse did not predict treatment response as measured by ≥25% reduction in FIQ-total score (OR = 1.16, 95% CI = 1.181.60, P = 0.35), while the drug status (paroxetine CR) was significantly associated with treatment response (OR = 2.51, 95% CI = 1.125.64, P = 0.02). Abuse history did not predict CGI-I (P = 0.32) or CGI-S (P = 0.74) improvements during treatment. After 12 weeks of treatment, subjects with sexual abuse history showed significantly lower mean change in health status (SF-36) than those without sexual abuse history (P = 0.04). Conclusions. Although, a significant proportion of patients with fibromyalgia reported a history of abuse, it does not appear to have any significant clinical correlates at baseline. History of abuse did not predict response to treatment in patients with fibromyalgia participating in a controlled trial of paroxetine controlled release. Prospective, well-designed studies are needed to confirm whether selective serotonin uptake inhibitors are effective in patients with fibromyalgia irrespective of their abuse history.