Clinical features of children with juvenile idiopathic arthritis using the ILAR classification criteria: A community-based cohort study in Taiwan

Background/Purpose: The aim of the study was to describe the clinical features of children affected by juvenile idiopathic arthritis (JIA) under the International League of Associations for Rheumatology-derived classification criteria in a community-based setting. Methods: Consecutive cases of JIA from defined geographic areas of Taiwan were diagnosed and followed in an observational cohort from 1995 to 2010. In addition to the clinical and laboratory data required for the International League of Associations for Rheumatology system, information about the medication and disease activity during the study period was also recorded. Results: Out of 292 children with chronic joint pain, 195 were diagnosed as JIA: systemic arthritis (19%), oligoarthritis (persistent 16.4%; extended 6.7%), polyarthritis rheumatoid factor-negative (11.8%), polyarthritis rheumatoid factor-positive (4.6%), psoriatic arthritis (1.5%), enthesitis-related arthritis (ERA; 37.4%), and undifferentiated arthritis (2.6%). Human leukocyte antigen-B27 was positive in 82.2% of patients with ERA. Uveitis was observed in 6.7% of patients. Disease-modifying anti-rheumatic drugs, including biologic medications, were used in 73.3% of children during the observational period. At the last follow-up, 40% of patients experienced a continuously active or relapsing course. Conclusion: Compared with previous reports on Western populations, a remarkably high prevalence was found in the ERA of the Chinese cohort, but a relatively low rate of uveitis. Ongoing disease activity was evident in a substantial number of children. These results provided a good starting point in understanding the epidemiology of this serious disease in the Chinese population.