Impact of shoulder, elbow, and knee joint involvement on assessment of rheumatoid arthritis using the American College of Rheumatology Core Data Set

Objective. To determine the most sensitive scoring method for assessment of rheumatoid arthritis (RA) disease activity using the American College of Rheumatology Core Data Set. Methods. The subjects were 4,530 patients with RA (mean age 57.9 years, mean disease duration 12.7 years) who participated in a large observational cohort study of RA patients. The 68 joints assessed were classified into 15 joint areas, and each joint variable was categorized based on the presence or absence of swelling or pain in these areas. Multiple linear regression and analysis of variance were used to evaluate the significance of effects of these 15 joint areas on variables for assessment of RA disease activity such as patient's assessment of pain on a visual analog scale (VAS), patient's and physician's global assessment of disease activity on a VAS, HAQ (Health Assessment Questionnaire), and Japanese HAQ. Results. Although the 3 most frequently affected joints were the wrist, metacarpophalangeal joints, and proximal interphalangeal joints, the 5 joints with the largest contributions to all of the variables assessed for disease activity were the shoulder, elbow, and knee joints, followed by the wrist and ankle joints. The combination of shoulder, elbow, and knee joints accounted for approximately 70% of the contribution to all the variables, while addition of the wrist and ankle joints increased this value to approximately 90%. Conclusion. Scoring for assessment of RA disease activity would be more sensitive if separate joints such as the shoulder, elbow, knee, wrist, and ankle joints were weighted differently.