Validity and reliability of a revised Japanese version of the Arthritis Impact Measurement Scales version 2 (AIMS2)

Abstract This study aims to evaluate the validity and reliability of a Japanese version of the Arthritis Impact Measurement Scales, version 2 (AIMS2) for patients with rheumatoid arthritis (RA). The Japanese version of the AIMS2 questionnaire was administered to 1643 patients with classical or definite RA at 11 hospitals nationwide in Japan. Reliability was assessed by a test-retest procedure, 4 weeks apart, using 75 randomly selected patients. Internal consistency was measured by Cronbach's α, and factor analysis was used to obtain the proportion of variance explained by the first factor in principal component analysis. The validity of the AIMS2 scales was assessed by internal standards. Internal consistency (α coefficients, 0.84-0.94), test-retest reliability (intraclass correlation coefficients, 0.75-0.93), and factor analysis (0.62-0.85) of the AIMS2 health status scales proved that they are highly reliable in the Japanese version. Validity, as measured by the relationships among the scores on the questionnaire items, was also sufficiently secured. The validity and reliability of the Japanese version of the AIMS2 are sufficient for all practical purposes when compared with the original and with other translated versions of the questionnaire.