Rheumatoid arthritis predictors found in undifferentiated large joint arthritis

Navkiran Sidhu, from the Leiden University Medical Center in the Netherlands, and colleagues examined clinical and serological features associated with RA development in patients with an undifferentiated mono- or oligo-articular large joint arthritis. A total of 221 consecutive patients with new-onset, undifferentiated large joint arthritis were followed; 45 had magnetic resonance imaging (MRI) of the hand and foot.

Patients mainly presented with knee or ankle monoarthritis. The researchers found that 17 percent of patients developed RA during the 12 months of follow-up. In multivariable analysis, autoantibody-positivity (anticitrullinated protein antibodies and/or rheumatoid factor) and MRI-detected synovitis in hands and feet were independently associated with RA-development (odds ratios, 10.29 and 7.88, respectively). The positive predictive value was 63, 55, and 100 percent for autoantibodies, MRI-detected synovitis, and the combination of both features, respectively. Diagnostic accuracy was improved with the addition of MRI-detected synovitis to autoantibody-status (net reclassification index, 18.1 percent).

“These findings demonstrate the increasing utility and importance of MRI in research and clinical practice,” the authors write. “Further work is required to design clinical algorithms in which there will be a cost-benefit ratio of using high resolution imaging.”