Objective: To determine the validity and usefulness of a modified Health Assessment Questionnaire (HAQ) for measurement of disease status and changes in disease status over time in patients with systemic sclerosis (SSc).
Methods: Since 1985, 1,250 patients attending the University of Pittsburgh Scleroderma Clinic have completed a modified HAQ annually. In addition to the standard HAQ questions about disability, the questionnaire includes visual analog scales (VAS) to evaluate SSc organ system symptoms, Raynaud's phenomenon, gastrointestinal (GI) tract and lung involvement, pain, and overall disease severity. In this study, the disability index (DI) (from the HAQ) and the VAS scores (on a 0-3 scale) were compared with various clinical and laboratory features recorded within 3 months of administration of the HAQ and VAS, using t-tests and Spearman's correlation tests.
Results: The HAQ DI correlated directly with skin involvement, scleroderma heart or kidney disease, tendon friction rubs, hand contractures, and proximal muscle strength. Over time, the DI correlated with changes in skin score and was a good predictor of survival. There was a significant improvement in the DI during a 2-year time period in patients treated with D-penicillamine. The VAS for digital ulcers, GI symptoms, and lung symptoms correlated very closely with subjective and objective findings for these organ systems. The presence of new digital ulcers or improvement in digital ulcers showed significant associations with the Vascular scale, new GI symptoms or improvement in GI symptoms and institution of H2-blockers showed appropriate strong correlations with the GI scale, and changes in the forced vital capacity had an excellent correlation with the Lung scale (r = 0.58, P < 0.001). By Cox regression analysis, the HAQ DI was one of the best predictors of survival.
Conclusion: These data provide convincing evidence that a self-administered questionnaire is an accurate and inexpensive tool to measure disease status changes in SSc. Prospective studies with the HAQ administered at regular intervals, as in controlled trials, should be performed to further assess the benefits and limitations of this instrument.