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Patient-Centered Rheumatoid Arthritis Disease Activity Assessment by a Modified RADAI

BURKHARD F. LEEB, PIA M. HAINDL, ADIL MAKTARI, THOMAS NOTHNAGL, and BERNHARD RINTELEN

ABSTRACT.

Objective. To evaluate the psychometric properties and validity of a modified version of the Rheumatoid Arthritis Disease Activity Index (RADAI) without joint counts in order to facilitate rapid and easy RA activity assessment in daily routine.

Methods. One hundred sixty-nine outpatients with RA completed the original RADAI and the modified RADAI-5. Simultaneously, the Disease Activity Score-28-erythrocyte sedimentation rate (DAS28-ESR) and C-reactive protein (DAS28-CRP) and the Simplified Disease Activity Index (SDAI) and Clinical DAI (CDAI) were applied. Cronbach's alpha, as a measure for internal consistency, and Spearman's rho, to evaluate the linear relationship of the different disease activity scales, were calculated. Rho was determined for the RADAI-5 and the core set measures to assess convergent validity. For agreement analysis, kappa statistics were calculated. An attempt was made to estimate the modified questionnaire's sensitivity to change.

Results. Means for the RADAI and the RADAI-5 were 2.8 (range 0.0–9.12) and 3.07 (0–10), respectively. Other means were as follows: DAS28-ESR 3.51 (0.28–6.67), DAS28-CRP 3.19 (1.12–5.83), CDAI 11.53 (0.0–44.6), and SDAI 12.36 (0.1–44.9). Cronbach's alpha was highest for the RADAI-5 (0.917) and lowest for the DAS28-CRP (0.510). The RADAI-5 was highly significantly correlated (all p < 0.0001) to all other instruments. However, kappa was < 0.65 for the relation of the RADAI-5 and all other scores except the RADAI. Changes of the RADAI-5, DAS28-ESR, and CDAI were significantly correlated (p < 0.001).

Conclusion. The RADAI-5, refraining from joint counts, was shown to be capable of measuring RA activity. Reliability and convergent validity could be proven. (First Release May 15 2008; J Rheumatol 2008;35:1294–9)

Key Indexing Terms:

RHEUMATOID ARTHRITIS
DISEASE ACTIVITY ASSESSMENT
QUESTIONNAIRE

From the 1st and 2nd Department of Medicine, Center for Rheumatology, Lower Austria; State Hospital Stockerau; Karl Landsteiner-Institute for Clinical Rheumatology, Stockerau, Austria.

B.F. Leeb, MD; P.M. Haindl, MD; A. Maktari, MD; T. Nothnagl, MD; B. Rintelen, MD.

Address reprint requests to Dr. B.F. Leeb, Karl Landsteiner-Institute for Clinical Rheumatology, Landstrasse 18, A-2000 Stockerau, Austria. E-mail: burkhard.leeb@stockerau.lknoe.at

Accepted for publication February 10, 2008.