Clinical Features and Treatment of Systemic JIA in Children (CST-SJIA)

Systemic juvenile idiopathic arthritis (sJIA) is a chronic inflammatory disease of childhood characterized by systemic manifestations such as recurrent fever, evanescent rash, lymphadenopathy, hepatosplenomegaly, and serositis, with or without arthritis. The disease may have a variable clinical course and can be associated with significant complications, including macrophage activation syndrome (MAS).

This study aims to clinically characterize children with sJIA and describe the different therapeutic modalities used in their management. The study will include children younger than 18 years who fulfill the 2019 PRINTO classification criteria for systemic juvenile idiopathic arthritis.

Clinical and laboratory data will be collected, including demographic characteristics, presenting manifestations, disease activity, inflammatory markers, relevant laboratory investigations, complications, and treatment modalities. Information regarding corticosteroids, conventional disease-modifying antirheumatic drugs, and biologic therapies will be documented according to the treatment received as part of routine clinical care.

Participants will be followed prospectively to assess their clinical course, disease activity, response to treatment, treatment-related outcomes, and occurrence of complications. The study is observational; treatment decisions will not be assigned by the study protocol and will remain according to the treating physician's clinical judgment.

The study will provide a clinical characterization of sJIA in children and describe outcomes associated with the different therapeutic modalities used in routine clinical practice.