Juvenile idiopathic arthritis (JIA) in infants is a very rare disease and diagnosis may be challenging.

This study aims to characterize JIA in infancy in terms of initial symptoms, diagnostic delay, JIA categories, drug treatment and clinical outcomes, and to compare these features with those of patients with later onset of JIA. Patients with JIA onset in the first year of life can be included if they have at least one follow-up visit within the first 2 years after disease-onset.

This study is coordinated by the pediatric rheumatology centers of Technical University Dresden and Charité Berlin as well as Deutsches Rheuma-Forschungszentrum (DRFZ) Berlin in Germany.

JIR-centers that enroll at least one patient will have one co-authorship per center for the planned publication.