Social security work disability and its predictors in patients with fibromyalgia

To determine prevalence and incidence of US Social Security Disability and Supplemental Security Income (SSD) in patients with fibromyalgia and to investigate prediction of SSD.

Over a mean of 4 years (range 1-13 years), we studied 2,321 patients with physician-diagnosed fibromyalgia (prevalent cases) and applied modified American College of Rheumatology (ACR) 2010 research criteria to identify criteria-positive patients.

During the study, 34.8% (95% confidence interval [95% CI] 32.9-36.8%) of fibromyalgia patients received SSD. The annual incidence of SSD among patients not receiving SSD at study enrollment was 3.4% (95% CI 3.0-3.9%), and 25% were estimated to be work disabled at 9.0 years of followup. By comparison, the prevalence of SSD in rheumatoid arthritis (RA) patients with concomitant fibromyalgia was 55.6% (95% CI 54.3-57.0%) and was 42.4% in osteoarthritis (OA). By study conclusion, 31.4% of SSD awardees were no longer receiving SSD. In univariate models, incident SSD in patients with fibromyalgia was predicted by sociodemographic measures and by symptom burden; but the strongest predictor was functional status (Health Assessment Questionnaire disability index [HAQ DI]). In multivariable models, the HAQ DI and the Short Form 36-item health survey physical and mental component summary scores, but no other variables, predicted SSD. Fibromyalgia criteria-positive patients had more SSD, but the continuous scale, polysymptomatic distress index derived from the ACR criteria was a substantially better predictor of SSD than a criteria-positive diagnosis.

The prevalence of SSD is high in fibromyalgia, but not higher than in RA and OA patients who satisfy fibromyalgia criteria. The best predictors of work disability are functional status variables.