PT - JOURNAL ARTICLE AU - Gladman, Dafna D. AU - Ye, Justine Y. AU - Chandran, Vinod AU - Lee, Ker-Ai AU - Cook, Richard J. TI - Oligoarticular vs Polyarticular Psoriatic Arthritis: A Longitudinal Study Showing Similar Characteristics AID - 10.3899/jrheum.210434 DP - 2021 Dec 01 TA - The Journal of Rheumatology PG - 1824--1829 VI - 48 IP - 12 4099 - http://www.jrheum.org/content/48/12/1824.short 4100 - http://www.jrheum.org/content/48/12/1824.full SO - J Rheumatol2021 Dec 01; 48 AB - Objective The objectives of this study were to determine whether patients with oligoarticular presentation differ from those with polyarticular presentation and to identify potential predictors for evolution of oligoarthritis to polyarthritis in patients with psoriatic arthritis (PsA).Methods Patients who entered the University of Toronto PsA clinic between 1978 and 2018 within 12 months of diagnosis were identified. Only patients with ≥ 2 clinic visits were included. Patients were followed at 6- to 12-month intervals according to standard protocol, which included demographics, clinical history, detailed clinical examination, laboratory information, and patient questionnaires. Radiographs were done at 2-year intervals. Oligoarthritis was defined by the presence of ≤ 4 inflamed joints and progression as an increase to ≥ 5 joints. Statistical analyses included logistic regression models as well as Weibull regression models, adjusted for age, disease duration, and sex.Results Of 407 patients, 192 (47%) presented with oligoarthritis. Whereas demographic features were similar to those with polyarthritis, more patients with polyarthritis presented with dactylitis and enthesitis. Similar joint distribution was observed, with small joints of the hands and feet being most commonly affected. Patients with polyarthritis had higher Health Assessment Questionnaire and lower 36-item Short Form Health Survey (SF-36) scores. Of the 192 oligoarticular patients, 117 (61%) remained oligoarticular and 75 (39%) progressed to polyarthritis. A lower SF-36 mental component summary (MCS) score was the predictor for progressing to polyarthritis.Conclusion Oligoarticular PsA occurs in 47% of patients with PsA and is similar to polyarticular disease, with most patients having small joint involvement. The only predictor for progression to polyarthritis was lower SF-36 MCS.