Validity and reliability of the twenty-eight-joint count for the assessment of rheumatoid arthritis activity

Abstract
Objective. To investigate the validity of the 28‐joint count for assessment of joint involvement in patients with rheumatoid arthritis (RA). Methods. Joint involvement as determined by the 28‐ and the 66/68‐joint count was compared using data from 735 prospectively studied RA patients. Results. The joints included in the 28‐joint count were more commonly involved than other joints, and findings from the 28‐joint count correlated highly with those from the 66/68‐joint count in all analyses. Conclusion. The 28‐joint count is a reliable and valid measure for joint assessment. It is easier to perform than the 66/68‐joint count, and it addresses the joints that are critically involved.