Psychometric properties of the Swedish version of the Scleroderma Health Assessment Questionnaire and the Cochin Hand Function Scale in patients with systemic sclerosis.

OBJECTIVES: To translate the visual analogue scales (VAS) in the Scleroderma Health Assessment Questionnaire (SSc HAQ) and the Cochin Hand Function Scale (CHFS) and to examine the reliability and validity of the Swedish versions of the instruments.

METHOD: The reproducibility, internal consistency, acceptability, and validity of the instruments were evaluated. Eighty-three consecutive patients participated in the evaluation of the SSc HAQ and 56 in the CHFS. Sixty-six per cent fulfilled the criteria for limited systemic sclerosis (lcSSc) and 29% for diffuse systemic sclerosis (dcSSc). The patients were assessed regarding disease parameters, hand involvement, and quality of life, the latter using the 36-item short form health survey (SF-36).

RESULTS: The reproducibility in the HAQ Disability Index (HAQ-DI), the VAS of pulmonary, digital ulcer, and overall disease severity, and in the CHFS was good (intra-class correlation coefficients, ICCs ≥ 0.75). The internal consistency was high in the HAQ-DI and the CHFS but lower in the VAS. The HAQ-DI showed higher correlations coefficients with physical-related scores in the SF-36 (rs = -0.600) than with mental-related dimensions (rs = -0.235). All VAS showed significant correlation with the item for general health (p < 0.05). The CHFS showed high correlation to hand-related items in the HAQ (rs = 0.858) and moderate correlation to the physical summary score in SF-36 (rs = -0.521). The instruments could not discriminate between lcSSc and dcSSc, although significant correlations between the CHFS and hand involvement (p < 0.05) indicate the ability of the CHFS to discriminate between mild and severe hand involvement.

CONCLUSIONS: The Swedish version of the SSc HAQ and the CHFS meet the requirements of reproducibility and concurrent validity. More studies are needed to examine the capacity of these instruments to discriminate between disease severities.