Kavanaugh A, Lee SJ, Weng HH, et al, University of California, San Diego, La Jolla, California, and other centers. Patient-derived joint counts are a potential alternative for determining disease activity score. J Rheumatol. 2010;37:1035-1041.
Patient-derived tender and swollen joint counts may be used to help determine disease activity in patients with rheumatoid arthritis (RA). Stronger correlations have been observed between physicians and patients for tender joints than for swollen joints.
Kavanaugh and colleagues compared physician- and patient-derived tender and swollen joint counts and Disease Activity Score using a 28-joint count (DAS28) in patients enrolled in a 24-week open trial of etanercept(Drug information on etanercept) alone versus etanercept plus methotrexate(Drug information on methotrexate) (MTX). Clinical Disease Activity Index (CDAI) and Simplified Disease Activity Index (SDAI) composite scores were calculated. Joint counts were performed at baseline, week 12, and week 24 by the physician and patient independently.
At baseline, mean DAS28 and patient-derived DAS28 were similar between the etanercept and etanercept plus MTX arms. The results of physician-derived tender and swollen joint counts were strongly correlated with the results of the patient-derived counts. The DAS28, CDAI, and SDAI all showed a high degree of correlation when calculated using physician or patient joint counts during the 24 weeks. The largest variation between physician and patient assessments occurred at intermediate levels of joint involvement.
The authors noted that using data collected from the patient may reduce the variation in joint counts that occurs even among trained medical professionals with RA experience but that they are not a substitute for physician-based assessments.
