- Enthesitis related arthritis. Subjects with polyarticular course JIA (ie, extended oligoarthritis, polyarthritis RF+, polyarthritis RF , systemic JIA with active arthritis but without active systemic features) must have a minimum of 5 active joints (an active joint is defined as a joint with swelling or, in the absence of swelling, limited range of motion accompanied by either pain on motion or tenderness) at screening and baseline to be eligible for study entry.