Reliability, validity, and responsiveness of the Persian version of the rheumatoid and arthritis outcome score (RAOS) in patients with rheumatoid arthritis

Abstract

The aims of this study were to cross-culturally translate the original rheumatoid and arthritis outcome score (RAOS) into Persian and evaluate its reliability, validity, and responsiveness in a group of patients with rheumatoid arthritis (RA). The questionnaire was translated through a standard forward-backward translation. A sample of 103 patients was asked to complete the Persian RAOS, the Short Form-36 (SF-36), and the arthritis impact measurement scale-short form (AIMS2-SF). To determine test-retest reliability, the Persian RAOS was readministered to a sample of 50 patients, 3-6 days after the first visit. To evaluate responsiveness, 50 patients completed the Persian RAOS at baseline and at the end of a pharmacological intervention. Test-retest reliability and internal consistency were assessed using intraclass correlation coefficient (ICC) and Cronbach's alpha, respectively. Construct validity was assessed by comparing the results of the RAOS with the Persian SF-36 and AIMS2-SF using Spearman's correlation coefficient. Responsiveness was assessed by the calculation of effect size (ES) and standardized response means (SRM). The acceptable level of ICC > 0.70 and Cronbach's alpha > 0.70 were obtained for the most RAOS subscales. As expected, moderate to strong correlations were observed between subscales of the RAOS and the SF-36/AIMS2-SF intended to measure similar constructs. The ES range of 0.18 to 0.51 and the SRM range of 0.25 to 0.91 were obtained for the RAOS subscales. In conclusion, the Persian RAOS is a reliable, valid, and responsive outcome measure for patients with RA suffering from arthritis in the lower limb joints.