Objective: To evaluate the measurement properties of the Health Assessment Questionnaire (HAQ) disability index (DI) for group comparisons in scleroderma trials, and to determine if the Scleroderma Health Assessment Questionnaire (SHAQ) visual analog scales confer any measurement advantage over the HAQ DI.
Methods: A computer search for articles describing the use of the HAQ DI and SHAQ in scleroderma was performed. Evidence supporting the sensibility, reliability, validity, and responsiveness of these measures was evaluated.
Results: The SHAQ has incremental face and content validity over the HAQ DI because it addresses scleroderma-specific manifestations that also contribute to disability. The HAQ DI has good concurrent validity, construct validity, and predictive validity. Whether SHAQ confers incremental construct, concurrent, or predictive validity over the HAQ DI is uncertain. The HAQ DI appears more reliable than the SHAQ; however, reliability studies provide insufficient data to ascertain if minimum standards have been achieved. Responsiveness of the HAQ DI subscales has been demonstrated.
Conclusion: The SHAQ has incremental face and content validity over the HAQ DI. The HAQ DI has greater reliability and demonstrated construct, concurrent, and predictive validity. Further investigation into the measurement properties of the HAQ DI and SHAQ visual analog scales, and their relation to the required standards of measurement is needed.