Epidemiologic investigation of juvenile rheumatoid arthritis: a ten-year study.

Background: Juvenile Rheumatoid Arthritis (JRA) is the most common chronic pediatric rheumatologic disease. There is a wide range of variation in disease subgroup distribution and evolution according to different populations, environments and genetic predisposition. This study was designed to evaluate epidemiologic characteristics of JRA in Iran. Methods: A cross-sectional studies was performed on children suffering from JRA according to American College of Rheumatology during 10 year (2002-2011). Patients' data was recorded in hospital questionnaires; Patients' age at the first presentation and time of diagnosis, sex, ethnicity, early clinical and constitutional presentations, joint involvement pattern and presence of associated diseases were evaluated. Results: In this study, 171 children (91 boys and 80 girls) were enrolled. The mean age of patients was 5.2±3.5 years at the time of presentation and 5.7±3.6 years when the diagnosis was confirmed. The most common type of disease was polyarticular arthritis (41.9%). The prevalence of pauciarticular and systemic onset subtype were 31.6% and 19.3%, respectively. According to ethnicity, the most common incidence was seen in Fars and Turk populations respectively. The most common constitutional presentation was fever. Fever and morning stiffness was significantly higher in polyarticular patients. Extra articular manifestation was seen in 40.4% patients. Among extra-articular manifestations, skin involvement was seen more than others. There was no correlation between sex and type of chronic arthritis. Uveitis was detected in 5.8% of our cases. The mean age was significantly higher in polyarticular group (6.04 year) in comparison to pauciarticular and systemic group (4.4 year in both groups) (P=0.005). There was no correlation between sex and type of chronic arthritis. Conclusion: The prevalence of JRA subgroups was different in Iran comparing with western countries and polyarticular disease was the most common subgroup in this study. Uveitis was less common in this study in comparison to studies in other countries. There is no sex predilection in each subgroup of JRA. [ABSTRACT FROM AUTHOR]