Validation of RAPID3 using a Japanese version of Multidimensional Health Assessment Questionnaire with Japanese rheumatoid arthritis patients: Characteristics of RAPID3 compared to DAS28 and CDAI

Objectives. To validate Routine Assessment of Patient Index Data 3 (RAPID3) using a Japanese version of Multidimensional Health Assessment Questionnaire (MDHAQ) with Japanese rheumatoid arthritis (RA) patients and to describe the characteristics of RAPID3 by comparison with Disease Activity Score 28 (DAS28) and Clinical Disease Activity Index (CDAI). Methods. The original MDHAQ was translated into Japanese with minor cultural modifications and was translated back in English. Test-retest reliability was evaluated in 50 Japanese RA patients and further validation was performed in 350 Japanese RA patients recruited by seven rheumatologists. RAPID3, CDAI, and DAS28 were assessed on two consecutive visits. Results. The test-retest reliability and the internal reliability of RAPID3 were excellent. Spearman's correlation coefficients between RAPID3 score versus CDAI score and DAS28 score were 0.761 and 0.555. However, the agreement measured by kappa (weighted) for RAPID3 category versus CDAI category and for RAPID3 category versus DA28 category were 0.225 (0.382) and 0.187 (0.336). The sensitivity and specificity of "RAPID3 <= 3 and swollen joint <= 1 "for predicting Boolean remission were 90.0% and 93.4%, respectively. Conclusions. RAPID3 obtained by Japanese MDHAQ was validated with Japanese RA patients and the remission criteria were found to have excellent clinical utility in usual care.