Validity and responsiveness of a self-administered foot evaluation questionnaire in rheumatoid arthritis

Objectives. A self-administered foot evaluation questionnaire (SAFE-Q) was developed by the Japanese Society for Surgery of the Foot (JSSF). The aim of this study is to evaluate the validity and responsiveness of the SAFE-Q in patients with rheumatoid arthritis (RA). Methods. In total, 180 patients with RA answered the SAFE-Q. Of 180 patients, 34 answered the SAFE-Q twice, preoperatively and postoperatively, to assess responsiveness. Construct validity was tested by comparing the 5 SAFE-Q subscales and the JSSF standard rating system for the RA foot and ankle scale (JSSF-RA), a Japanese version of the Health Assessment Questionnaire (JHAQ), disease activity score in 28 joints (DAS28), simplified disease activity index (SDAI), and clinical disease activity index (CDAI). Responsiveness was examined by calculating the standardized response mean (SRM) and effect size (ES) 3 months after surgery. Results. There were moderate correlations between the SAFE-Q and the JSSF-RA and JHAQ. Conversely, a low correlation was observed between the SAFE-Q and DAS28, SDAI, and CDAI. The responsiveness was high, with an SRM of 0.9 and ES of 0.7 for pain subscales. Conclusion. SAFE-Q is a useful tool for assessing the foot and ankle in RA patients.