Assessing hand and global disability in a cohort of Algerian patients with systemic sclerosis: Construct validities of the Arab Hand Function Index and the Arabic Health Assessment Questionnaire

Objective: The study aimed to assess the construct validity of the Arab Hand Function Index and the Arabic Health Assessment Questionnaire in Algerian patients with systemic sclerosis. Methods: Consecutive Algerian patients who fulfilled the American College of Rheumatology/European League Against Rheumatism criteria for systemic sclerosis were included. In addition to disease characteristics, global disability and hand disability were assessed using the Arabic Health Assessment Questionnaire and the Arab Hand Function Index, respectively. Construct validity was assessed by convergent and divergent validity (Spearman's rank correlation coefficient) and factor analysis. The scale reliability was assessed using the Cronbach's alpha. Results: We evaluated 100 systemic sclerosis patients (83 females) of mean +/- standard deviation age 46.7 +/- 12.3 years, including 59 limited cutaneous systemic sclerosis and 41 diffuse cutaneous systemic sclerosis. Raynaud's phenomenon was detected in 99 patients and digital ulcers in 25. Gastrointestinal tract involvement and interstitial lung disease were detected in 86/100 (86%) and 46/72 (63.9%) patients, respectively. Anti-topoisomerase I and anti-centromere antibodies were detected in 33/76 (43.4%) and 23/76 (30.3%) patients, respectively. The Arab Hand Function Index had a good construct validity with a total score explaining 61% of the variance of the Arabic Health Assessment Questionnaire which also had a good construct validity. Factor analysis of the Arab Hand Function Index and the Arabic Health Assessment Questionnaire items extracted two factors explaining 64% of the variance for the Arab Hand Function Index and one factor explaining 55% of the variance for the Arabic Health Assessment Questionnaire. The Arab Hand Function Index and the Arabic Health Assessment Questionnaire were reliable questionnaires with a Cronbach's alpha >0.8. Conclusion: In Algerian patients with systemic sclerosis, Arab Hand Function Index and Arabic Health Assessment Questionnaire have a good construct validity and reliability.