To design and validate a clinical method for scoring irreversible long term articular damage in rheumatoid arthritis (RA).
The rheumatoid arthritis articular damage score (RAAD score) is based on examination of 35 large and small joints. Concise definitions were formulated to score each joint on a three point scale (0, no irreversible damage; 1, partially damaged; 2, severe damage, ankylosis, or prosthesis). The RAAD score was determined for 121 patients with RA with a large range of disease duration. Interobserver agreement was studied in 39 patients scored by three observers. Data on disease duration, Health Assessment Questionnaire, disease activity score, and Larsen score were collected for 121, 78, 47, and 45 patients, respectively.
The RAAD score correlated well with the Larsen score (r(s)=0.81) and disease duration (r(s)=0.68) and (as intended) not with disease activity (r(s)=0.10). Good interobserver agreement was found for total scores and individual joints. The wide range of RAAD scores for patients with the same disease duration suggested good discriminating power, especially after >10 years.
The RAAD score is a quick and feasible method for measuring the long term articular damage in large RA populations. It has good reliability and construct validity and deserves further study to assess its discriminant validity.