Work Disability in Scleroderma is Greater than in Rheumatoid Arthritis and is Predicted by High HAQ Scores

OBJECTIVES: To estimate the frequency of work disability (WD) in a cohort of patients with Systemic Sclerosis (SSc) vs an internal control group of patients with rheumatoid arthritis (RA) with a known high frequency of WD; and to investigate the association between WD and other factors including Health Assessment Questionnaire Disability Index (HAQ-DI) scores, HAQ pain, age, sex, disease duration and education level. METHODS: Cross-sectional data on WD status were obtained from a questionnaire sent to all SSc (n = 35 limited [lcSSc], 26 diffuse [dcSSc]) and a subset of RA patients (n=104) from a rheumatology practice. WD data, HAQ-DI scores, and demographic/clinical features (age, sex, high school education, disease duration and SSc disease subtype [dcSSc vs lcSSc]) were recorded. RESULTS: The proportion with WD was 0.56 in SSc (95% CI: 0.43-0.68) vs 0.35 in RA (95% CI: 0.25-0.44), p= 0.009. HAQ-DI scores were significantly higher in work-disabled SSc and RA patients vs those who were employed (p=0.0001, and p <0.0001). Multivariate logistic regression analysis demonstrated that higher HAQ-DI scores (β=1.78, p <0.001), disease type (dcSSc, lcSSc, RA) (β=1.32 for dcSSc, p=0.032), and self-reported disease duration (β=0.04, p=0.042) were significantly associated with WD (R(2)=0.311). Adding a work-related factor (self-reported physically demanding work) improved the regression model (R(2)=0.346) and strengthened the HAQ-DI (β=1.86, p <0.001) and lcSSc (β=1.24, p=0.024) coefficients. CONCLUSION: The frequency of WD in SSc was high and was greater than in RA. SSc (and dcSSc) had significantly more WD than RA. The HAQ-DI was strongly associated with WD in SSc.