Subtype frequencies, demographic features, and remission rates in juvenile idiopathic arthritis - 265 cases from a Turkish center.

Juvenile idiopathic arthritis (JIA) is the most common cause of chronic arthritis in children. It is a group of heterogeneous disorders that have chronic arthritis as a common feature. It has a worldwide distribution and many studies have shown that subtype frequencies in JIA seem to be showing geographical distribution. The aim of this study was to define subtype frequencies, demographic features, and the rates of macrophage activation syndrome, uveitis and remission in Turkish JIA patients. The files of all JIA patients (378 cases) that were being followed in Pediatric Rheumatology Clinic of our institution, between May 2010 and February 2016 were reviewed. Two hundred and sixty-five patients were included into the study. Gender, JIA subtype, age at diagnosis, age at the initial symptoms, JIA medications, uveitis presence, JIA status at the time of enrollment were recorded from the files. There were 87 enthesitis related arthritis, 87 oligoarthritis (81 persistent, 6 extended), 36 rheumatoid factor (RF) negative polyarthritis, 35 systemic arthritis, 10 RF-positive polyarthritis, 5 psoriatic arthritis and 5 undifferentiated arthritis cases. Mean age at diagnosis was 9.9 ± 4.9 years and male/female ratio was 1.05. Uveitis was found in 4.5% of the cases. Biologics were used in 26% of the patients. At the time of enrollment, 69% of the patients were under remission while 31% of them were active. Systemic arthritis and persistent oligoarthritis cases were the groups that most commonly achieved remission, while patients with polyarticular involvement, namely RF positive polyarthritis, RF negative polyarthritis and extended oligoarthritis patients were the groups with high number of active patients. In conclusion, JIA is a heterogeneous group of disorder, and differences in subtype frequencies from country to country make it even more heterogeneous disease. Patients with polyarticular involvement may need early and aggressive treatment to control the disease activity.