Adaptation, reliability and validity testing of a Persian version of the Health Assessment Questionnaire-Disability Index in Iranian patients with rheumatoid arthritis.

Objective: The aim of the present study was to culturally adapt and evaluate reliability and validity of Health Assessment Questionnaire-Disability Index (HAQ-DI) in Iranian patients with rheumatoid arthritis (RA).

Methods: 234 patients with RA for validation study, Eighty-six participants for reliability study. Methods: Test-retest relative reliability and internal consistency of Persian version of HAQ-DI were examined by intraclass correlation coefficient (ICC) and Cronbach's alpha, respectively. Additionally, HAQ-DI construct validity (Spearman's correlation) was examined using Persian version of Short-Form 36 Health survey (SF-36), activity and severity parameters.

Results: Persian version of HAQ-DI total score showed excellent test-retest reliability (ICC = 0.98) and internal consistency (Cronbach's alpha = 0.95). Spearman's correlations between the total PHAQ-DI score and activity and severity parameters were above 0.55. Correlation between PHAQ-DI and SF-36 Physical Health were higher as compared with SF-36 Mental Health.

Conclusions: Persian version of HAQ-DI is a reliable and valid culturally-adapted instrument in order to measure functional limitations in Iranian people with RA.