Autoantibody positivity and subclinical syno- vitis are independent predictors of rheumatoid arthritis (RA) among patients presenting with undifferentiated large joint arthritis, according to a study published in Rheumatology. Research- ers examined clinical and serological features as- sociated 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 magnet- ic resonance imaging (MRI) of the hand and foot. Patients mainly presented with knee or ankle monoarthritis. Among participants, 17% 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 pre- dictive values were 63%, 55%, and 100% for autoantibodies, MRI-detected synovitis, and the combination of both features, respectively. Di- agnostic accuracy was improved with the addi- tion of MRI-detected synovitis to autoantibody- status (net reclassification index, 18.1%).