Objective. - To test the reliability and validity of a modified and translated version of the original Health Assessment Questionnaire (HAQ) on patients with rheumatoid arthritis (RA).

Method. - A cohort of 184 RA patients from different Arabic countries (Egypt, Saudi Arabia, Sudan, Syria, Bahrain, Kuwait and Morocco) were recruited and asked to participate in the study. Two questions had been changed to suit the Arabic culture and to tackle some aspects that are commoner to be performed in the Arabic culture. After modification, translation and retranslation of the questionnaire, it was administered to the selected patients and tested for internal consistency, reliability and construct validity by correlating the yield of the questionnaire with other disease activity parameters. The questionnaire was administered again after a 1-week interval for evaluation of the reliability of this test. The modified questions were tested for their loyalty to the principal component and comparing their correlation with that of the other unchanged items.

Results. - Test-retest showed strong reliability with a high percentage of agreement and high values for Kappa. Internal consistency showed a high value for standardized alpha (Cronbach's): 0.979 that did not show any significant change if any of the 20 items had been eliminated. The modified questionnaire had shown a strong validity when correlating its results with other disease activity parameters. This correlation was the strongest with tender joint count (TJC), Ritchie articular index (RAI), morning stiffness (MS) and visual analogue scale (VAS) and the least (but still significant) with rheumatoid factor (RF).

Conclusion. - The Arabic HAQ is a reliable and valid instrument that can be self-administered to Arabic RA patients to evaluate their functional disability. Its measurement properties were comparable to versions in other languages.