Background/Purpose: Fibromyalgia is a contested disorder whose diagnosis depends largely on self-report. It is reportedly also associated with a high rate of work disability, but there have been no detailed studies of work disability in fibromyalgia. In addition, disabled status is difficult to determine because there are no clearly observable abnormalities or reliable assessments methods to determine work disability. In this study we determined the rate of a work disability award and its predictors.

Methods : For up to 13 years, we studied a cohort of 2,322 fibromyalgia patients, who were between the ages of 21 and 64 years, using mailed and Internet questionnaires at 6-month intervals. 591 patients were receiving US Social Security disability (SSD) awards at entry to the cohort, and were not studied further. The remaining 1,730 constituted the study sample and were evaluated using Cox regression.

Results : For the entire sample (N=2,322) the prevalence of SSD was 34.8% (95% CI 32.9, 36.8). Over 13 years of follow-up of the non-disabled sample at study entry, a SSD prevalence of 25.5% was noted. The annual incidence rate for this group was 3.4% (3.0, 3.9%) annually and 25% of patients were disabled at 9.0 years (Figure 1). As shown in Table 1, a wide variety of univariate predictors (adjusted for age and sex) at the first observation were associated with future work disability, including younger age, abnormal mood, functional status as measured by the Health Assessment Questionnaire disability index (HAQ), increased BMI, current smoking, the polysymptomatic distress scale (PSD (“fibromyalgianess)), meeting ACR 2010 criteria, the SF-36 PCS and MCS scales, VAS fatigue, VAS pain, and rating one’s self as being disabled or being unemployed. College education was protective against future SSD. In multivariable Cox regression, only HAQ disability (Relative Risk 2.5 (1.8, 3.6)), rating one’s self as disabled (RR 5.9 (3.6, 9.7), and being unemployed (RR 3.3 (1.9, 5.8) were significant predictors of future SSD.

Conclusion: The receipt of a SSD award is common in fibromyalgia, with an annual incidence of 3.4% (3.0, 3.9%). Although many variables were predictive of SSD in univariate models, only self-report of functional status and current unemployment and/or self-reported disability predicted future SSD. One explanation for the few predictors is that BMI, smoking, education and symptoms contribute to functional status, which then dominates all other predictors.

Table 1. Univariate predictors of SSD, adjusted for age and sex

No ethnicity groups were statistically significant predictors.