Adaptation and validation of an Arabic version of a 10‐item patient‐reported outcome measure of physical function in rheumatoid arthritis

Abstract

Aim To adapt and validate an Arabic version of the short form of physical function measure (PF‐10a), a generic questionnaire for physical function, in Egyptian patients with rheumatoid arthritis (RA). Methods After standardized linguistic validation of the Arabic version of PF‐10a, with forward and backward translation, the questionnaire was completed by 70 Egyptian RA patients who were diagnosed according to American College of Rheumatology/European League Against Rheumatism 2010 classification criteria, on two occasions 3‐5 days apart. The internal consistency and test–retest reliability were evaluated using Cronbach's alpha and intra‐class correlation. The content validity of the Arabic PF‐10a was tested against Health Assessment Questionnaire Disability Index (HAQ‐DI), Clinical Disease Activity Index (CDAI) and Disease Activity Score in 28 joints using erythrocyte sedimentation rate (DAS28‐ESR). In addition, serology results, hand radiographs, and treatments received were all recorded. Results Most of our patients were female (88.6%) with a mean age of 49.2 ± 10.5 years. They had a mean disease duration of 7.3 ± 7 years and an active disease with a mean CDAI of 33.1 ± 12.6. The mean value of PF‐10a was 34.6 ± 6.2. The Cronbach's alpha for Arabic PF‐10a was 0.904. Intra‐CLASS CORRELATION was 0.897. Arabic PF‐10a correlated strongly with HAQ‐DI (−0.746), moderately with CDAI, patient global assessment, and pain (−0.457, −0.417, and −0.371 respectively). Conclusion The validation study showed that the Arabic PF‐10a had acceptable psychometric characteristics, in terms of internal consistency and construct validity. The Arabic PF‐10a is a reliable and valid instrument to be used by Arabic RA patients.