Filling the Gap: Toward a Disease Activity Tool for Systemic Juvenile Idiopathic Arthritis Systemic juvenile idiopathic arthritis (sJIA) accounts for 5%–15% of all children with chronic arthritis seen in… jrheum.org Clinical Juvenile Arthritis Disease Activity Score proves to be a useful tool in treat-to-target therapy in juvenile idiopathic arthritis ard.bmj.com