Validation of French version of the Scleroderma Health Assessment Questionnaire (SSc HAQ)

Abstract

The modified Scleroderma Health Assessment Questionnaire (SSc HAQ) is a functional score to assess systemic sclerosis (SSc) comprising the HAQ disease index (HAQ-DI) plus five specific visual analogue scales (VAS). Since it was validated in English-speaking patients only, its general use in any other language necessitates prior cross-cultural adaptation and validation. We designed this study to assess its value in French-speaking patients and to validate the French version according to international recommendations. We elaborated a French version using the "forward-backward" method. We then validated its psychometric properties with 100 consecutive SSc French-speaking patients who had undergone simultaneous clinical and paraclinical examination. In addition, we calculated the SSc HAQ score, a new outcome measure, which is obtained by pooling the eight domains from the HAQ-DI with the five organ VAS. Our study confirmed the psychometric properties of the SSc HAQ in non-English-speaking patients with (a) structural validity: the major component analysis, performed on the HAQ-DI and the five VAS, yielding a two-factor structure; (b) convergent validity: with high correlation coefficients between the SSc HAQ score and the physical component score of the SF-36 (r=-0.74, p<0.0001); (c) discriminant validity: the SSc HAQ score was better in patients with limited than with diffuse SSc (0.5+/-0.5 vs 1.1+/-0.7, respectively, p<0.0001) in relation to the number of clinical involvements; (d) reproducibility was high using the test-retest procedure (r=0.98). This study showed the value of the SSc HAQ, which is a simple, discriminant, reproducible self-administered questionnaire to evaluate French-speaking SSc patients. In addition, we suggest the use of a new outcome measure, the SSc HAQ score, to assess this systemic disease more accurately.