The Rheumatoid and Arthritis Outcome Score (RAOS) was recently developed to evaluate functional disability and quality of life in rheumatoid arthritis (RA) patients suffering from lower limb symptoms. The aims of this study were to cross-culturally adapt the RAOS into French and to assess its psychometric properties, in particular, responsiveness following intra-articular therapy.
The French RAOS was developed according to cross-cultural guidelines and was then evaluated in symptomatic RA patients with lower limb joint involvement. The psychometric properties assessed were - feasibility: percentage of missing data and floor and ceiling effects; reliability: intra-class correlation coefficients (ICC, and Bland and Altman representation; internal consistency: Cronbach's alpha; construct validity by correlation with the SF-36 and HAQ (Spearman's rank test); responsiveness to intra-articular corticosteroid injection (hip, knee, hindfoot) using standardised response mean (SRM) and effect size.
Sixty patients were included (mean age 50.1±10.5 years). Neither floor nor ceiling effects were observed. Reliability was good with ICC for different RAOS subscales ranging from 0.76 to 0.91. Results for internal consistency (Cronbach's alpha ranging from 0.73 to 0.91) and construct validity were good. The responsiveness was moderate to large with SRMs ranging from 0.75 to 0.87 and effect sizes from 0.77 to 1.75 at two weeks following intra-articular corticosteroid injection.
The French version of the RAOS demonstrated good psychometric properties to capture functional disability and quality of life in RA. Moreover, the results suggest that the RAOS could be used as an outcome in trials evaluating single joint intra-articular injections.