Objective: To compare the Routine Assessment of Patient Index Data 3 (RAPID3) on a Multidimensional Health Assessment Questionnaire (MDHAQ) with the Disease Activity Score (DAS28), Clinical Disease Activity Index (CDAI), and individual core data set measures for correlations, agreement of activity levels, and time to score.
Methods: Four rheumatologists each assessed 50 patients with rheumatoid arthritis in "real-time" clinical care. Patients completed an MDHAQ. The rheumatologist then calculated RAPID3 (physical function, pain, patient global estimate), performed a 28-joint count, assigned a physician global estimate, and scored a CDAI, each timed by an observer. Erythrocyte sedimentation rate (ESR) was tested on the same date, and the DAS28-ESR was computed later, again timed by an observer. Spearman's rank-order correlations and comparisons of patients classified as high activity, moderate activity, low activity, and remission according to the DAS28, CDAI, and RAPID3 were computed and compared with kappa statistics. A second study of 25 "paper patients" was also performed to compare time to score the DAS28, CDAI, and RAPID3 on a 0-10 versus 0-30 scale. Mean and median times to score each index were computed.
Results: The 3 indices were correlated significantly, including agreement for >80% of patients for high/moderate activity. The mean time to perform a 28-joint count was 94 seconds, and the mean times to score the DAS28, CDAI, RAPID3 on a 0-10 scale, and RAPID3 on a 0-30 scale were 114, 106, 9.6, and 4.6 seconds, respectively.
Conclusion: RAPID3 scores provide similar quantitative information to DAS28 and CDAI, while calculated on a 0-30 scale in about 5% of the time.