Predictors of Perceived Functional Status in Early Systemic Sclerosis: A Prospective Longitudinal Study of an Early Disease Cohort.

Abstract

The modified Health Assessment Questionnaire (M-HAQ) is a well-established patient-reported outcome measure in systemic sclerosis (SSc) studies that reflects how a patient functions in several categories of activities of daily living. This study analyzed clinical, demographic, and socioeconomic factors that predict M-HAQ scores over time. This study included 388 patients with baseline M-HAQ scores from the Genetics versus Environment in Scleroderma Outcome Study (GENISOS) early disease cohort with a mean disease duration of 2.5 years, mean follow-up time of 3.9 years, and median follow-up of 7.2 years. A total of 1,950 M-HAQ measurements were analyzed. Baseline disease characteristics were recorded, and the association of these characteristics with the M-HAQ score was analyzed at baseline and longitudinally. Lower income and education levels, older age, and more severe skin involvement at enrollment were independent predictors of worse perceived functional disability over time (i.e., higher longitudinal M-HAQ levels). Higher longitudinal modified Rodnan skin scores correlated with higher M-HAQ scores, whereas higher longitudinal forced vital capacity percentage predicted values correlated with lower M-HAQ scores over time (P < 0.001 for both univariable and multivariable analyses). Moreover, higher baseline M-HAQ scores predicted higher mortality (hazard ratio 1.29, 95% confidence interval 1.09-1.52, P=0.003). This large, longitudinal study of early disease SSc demonstrates that severity of skin disease and socioeconomic factors such as educational level and income are important predictors of perceived functional disability in SSc.