Standard Disease Activity Measures May Underestimate Foot Synovitis in RA

The 28-joint Disease Activity Score using the erythrocyte sedimentation rate, Clinical Disease Activity Index, and Simplified Disease Activity Index-disease activity measures that do not provide a direct assessment of the foot-perform poorly in detecting foot synovitis in patients with rheumatoid arthritis. This is in contrast to the 1981 American College of Rheumatology (ACR) and 2011 ACR/European League Against Rheumatism (EULAR) remission criteria, which use full joint counts.

Wechalekar and coworkers assessed 123 patients at baseline and 6 months after the start of a response-driven combination disease-modifying antirheumatic drug protocol. Remission was assessed using the disease activity measures and Boolean-based criteria. The prevalence of foot synovitis and the mean swollen/tender foot joint count were estimated in patients who met any of these criteria.

Application of the 1981 ACR criteria and the 2011 ACR/EULAR criteria classified the least number of patients as being in remission and evidence of foot synovitis was minimal. Ongoing foot synovitis was present in a substantial proportion of patients who met the 28-joint count criteria for remission.

The authors noted that if treatment decisions are made solely on the basis of criteria that omit foot joint assessment, patients may be at risk for ongoing damage.