Systemic Juvenile Idiopathic Arthritis

The reason for this study is to see if the study drug baricitinib is safe and effective in participants from 1 year to less than 18 years old with systemic juvenile idiopathic arthritis (sJIA). Participants are assigned to 1 of 2 cohorts. In cohort 1, participants will receive baricitinib or tocilizumab reference. In cohort 2, participants will receive baricitinib.

This study aims to assess and characterize the treatment patterns, and long-term clinical outcomes and demographic characteristics of patients diagnosed with Familial Mediterranean fever (FMF) and Still's disease (including systemic juvenile idiopathic arthritis \[SJIA\] and adult-onset Still's disease \[AOSD\]) that received canakinumab for at least 6 months.