Correlates of the disability index of the health assessment questionnaire - A measure of functional impairment in systemic sclerosis

Objective. To evaluate functional impairment in systemic sclerosis (SSc) pa tients with diffuse cutaneous scleroderma at the time of entry into a trial of a therapeutic intervention (D-penicillamine). Methods. The 20-item Disability Index of the Health Assessment Questionnair e (HAQ-DI) was administered to 134 patients as they entered a multicenter t rial of high-dose versus low-dose D-penicillamine, All patients had diffuse SSc of <18 months' duration. SSc patients who had severe organ system invo lvement and recent renal crisis and who were receiving prednisone >10 mg/da y were excluded from entry. Logistic regression modeling was used to examin e the relationship of HAQ-DI scores to SSc skin and organ system involvemen t. Odds ratios (OR) and 95% confidence intervals (95% CI) were used to esti mate effects. Results. The mean (+/-SD) HAQ-DI score at entry was 1.04 +/- 0.67. Fifty-th ree percent of patients had HAQ-DI scores greater than or equal to 1.0 (sig nifying moderate-to-severe functional impairment). Multivariate logistic re gression demonstrated that impaired fist closure greater than or equal to 2 3 mm (OR 4.24, 95% CI 1.68-10.70), reduced handspread less than or equal to 175 mm (OR 4.5, 95% CI 1.80-11.24), joint tenderness count greater than or equal to 1.0 (OR 2.93, 95% CI 1.16-7.40), age greater than or equal to 43 years (OR 2.44, 95% CI 1.01-5.95), platelet count greater than or equal to 330,000/mm(3) (OR 2.30, 95% CI 0.96-5.57), and female sex (OR 2.43, 95% CI 0.77-7.73) were the most important correlates of HAQ-DI scores greater than or equal to 1.0. Conclusion. Increased HAQ-DI scores at baseline were correlated,with reduce d fist closure, reduced handspread, elevated platelet count, presence of te nder joints, older age, and female sex. The most important contributor to f unctional impairment was hand dysfunction, Even within the first 18 months after SSc onset, moderate-severe functional impairment (HAQ-DI scores great er than or equal to 1.0) was frequent (53% in this group of diffuse SSc pat ients. In early diffuse SSc, the self-administered HAQ-DI is therefore a va luable assessment of function that correlates with objective physical and l aboratory measures of SSc disease involvement. Abnormal HAQ-DI scores may s upport patient claims of functional impairment, help to focus physician att ention on implementing measures to reduce functional impairment, and be use ful in reflecting the disease course over time.