Systemic Sclerosis Causes Increased Disability Over Time

Disability worsens over time in patients with systemic sclerosis (SSc). Diffuse disease and severity of breathing problems are the strongest determinants of disability; others include joint pain and contractures, fatigue, and depression.

Schnitzer and associates performed a multicenter, longitudinal study of 745 patients with SSc in the Canadian Scleroderma Research Group registry. The Health Assessment Questionnaire (HAQ) was used to assess disability. The baseline characteristics of interest were age, sex, disease duration, and disease subset. The time-dependent variables included study visit number and 5 disease-specific questions developed to be administered with the HAQ. Two types of models were used to determine the overall trend of the HAQ over time.

Disability in SSc worsened over time in all study models. The raw, or undifferentiated, change in HAQ score was 0.022 per year. After accounting for various levels of informative patient dropout, the increase in HAQ score ranged from 0.039 per year to 0.071 per year. Using the most conservative of these estimates, this was equivalent to an increase in the HAQ score of 0.12 over 3 years.

The authors noted that their data provide important prognostic information and have ramifications for future studies using the HAQ as the outcome measure.