Baseline Clinical Features and Biomarker Profiles of the Childhood Arthritis and Rheumatology Research Alliance Systemic Juvenile Idiopathic Arthritis-Associated Lung Disease Cohort

Objectives: Chronic lung disease is a potentially life-threatening complication of systemic juvenile idiopathic arthritis (SJIA-LD). However, its natural history, etiology, and effective management are unclear. We aimed to describe the baseline characteristics and biomarker profiles of the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry SJIA-LD cohort. Methods: Baseline data from all CARRA Registry patients with SJIA and those with SJIA-LD were included and analyzed. Lung disease–specific data were obtained using a standardized case report form through REDCap Cloud. Plasma biomarker profiles were determined using a custom Luminex panel. Results: A total of 37 patients with SJIA-LD from 16 CARRA sites were identified and compared to all 928 patients with SJIA without known LD in the CARRA Registry. Patients with SJIA-LD were significantly younger at disease onset and were more likely to be of Asian descent. A higher medication burden was also found. Patients with SJIA-LD had higher levels of multiple lung injury biomarkers, cytokines, and chemokines compared to patients with both active and inactive SJIA without LD and healthy controls. Cluster analysis proposed three groups of SJIA-LD patients with distinct biomarker patterns reflecting differences in proinflammatory cytokines, type II chemokines, and markers of macrophage activation syndrome (MAS). Conclusions: The CARRA SJIA-LD Cohort exhibits distinct clinical features, higher medication burden, frequent MAS, and plasma biomarker patterns specific to SJIA-LD compared to patients with SJIA without LD. A study is ongoing to assess more detailed clinical features, disease progression, patient-reported outcomes, and associated immune biomarkers.