Objective. The purposes of this study were to assess the clinical characteristics of patients with juvenile idiopathicarthritis (JIA) who fulfill the ClASsification criteria for Psoriatic ARthritis (CASPAR) 18 years after disease onset in apopulation-based setting and to identify features likely to predict psoriatic arthritis (PsA).

Methods. Patients with JIA from defined geographic regions of Denmark, Finland, Norway, and Sweden with dis-ease onset from 1997 to 2000 were enrolled prospectively and followed up for 18 years. Clinical, laboratory, and hered-ity data for psoriasis were collected. Patients were classified according to the International League of Associations forRheumatology (ILAR) criteria at baseline, and we applied ILAR and CASPAR criteria at 18 years. Logistic regressionwas performed to study the effects of JIA-related characteristics and heredity for psoriasis on being classified for PsA.

Results. Among the 510 patients enrolled, 434 participated in the 18-year follow-up, 28 (6.5%) met the ILAR cri-teria, and 41 (9.4%) fulfilled the CASPAR criteria. Patients with wrist or subtalar joint involvement at onset had higherodds of being classified with PsA at 18 years (odds ratio [OR] 3.3, P = 0.02 and OR 12.9, P = 0.01, respectively). Pres-ence of psoriasis, nail abnormalities, or dactylitis showed significant association with development of PsA (OR 20.2,P < 0.001; OR 11.6, P = 0.002; and OR 43.4, P < 0.001, respectively).

Conclusion. CASPAR criteria identify more patients with PsA compared with ILAR criteria and may better capturethe heterogeneous nature of the disease. Presence of psoriasis and dactylitis at disease onset were the strongest pre-dictors for the development of PsA. Further studies on the utility of CASPAR criteria in patients with JIA are needed