IL1B and juvenile idiopathic arthritis: 1050 (91%) of 1152 patients started initial treatment with a TNFi, although among the 97 patients with systemic juvenile idiopathic arthritis, IL-6 and IL-1 inhibitors were the most common first biologic therapy (55 [57%] patients initiated treatment with the IL-6 inhibitor tocilizumab; 28 [29%] patients initiated treatment with an IL-1 inhibitor).