Joint counts to assess rheumatoid arthritis for clinical research and usual clinical care: advantages and limitations

Abstract

A joint examination is prerequisite to a diagnosis of rheumatoid arthritis (RA), and quantitative counts of swollen and tender joints are the most specific of the 7 RA Core Data Set measures for patient assessment. Therefore, joint counts are weighted of greater importance than the other 5 Core Data Set measures in American College of Rheumatology response criteria and all RA indices in which it is included. Nonetheless, several limitations to the joint count have been recognized: (1) poor reproducibility with a requirement to be performed by the same observer at each visit; (2) likelihood to improve with placebo treatment as much or more than the other 5 RA Core Data Set measures; (3) similar or lower relative efficiencies than global and patient measures to document differences between active and control treatments in clinical trials; (4) improvement over 5 years while joint damage and functional disability may progress; (5) lower sensitivity in detecting inflammatory activity than ultrasound and magnetic resonance imaging. Most visits to a rheumatologist do not include a formal quantitative joint count. Quantitative patient self-report data are as sensitive to change and as informative about prognosis and outcomes as joint counts. It may be suggested that a careful qualitative (nonquantitative) joint examination, supplemented by quantitative self-report questionnaire scores to interpret physical examination findings, may be adequate to monitor patients and document changes in status in busy clinical settings.