Bayesian comparative effectiveness study of four consensus treatment plans for initial management of systemic juvenile idiopathic arthritis: FiRst-Line Options for Systemic juvenile idiopathic arthritis Treatment (FROST).

FiRst-Line Options for Systemic juvenile idiopathic arthritis Treatment (FROST) will provide the first prospective comparison of Childhood Arthritis and Rheumatology Research Alliance's (CARRA's) consensus-derived non-biologic versus biologic management strategies in systemic juvenile idiopathic arthritis, performed in a real-world setting wherein each patient receives standard-of-care treatment selected by the treating physician. Outcomes include clinician- and patient-/family-reported outcomes, empowering both physician and patient decision making in new-onset systemic juvenile idiopathic arthritis.