Management of Juvenile Idiopathic Arthritis

Classification and Disease Activity Assessment

The American College of Rheumatology defines JIA as arthritis of unknown etiology beginning before age 16 years and persisting for at least 6 weeks, with other known conditions excluded 2
For treatment purposes, patients are grouped by clinical phenotypes rather than strict ILAR categories: polyarthritis (≥5 joints), sacroiliitis, and enthesitis 1, 3
Disease activity is assessed using the clinical Juvenile Disease Activity Score based on 10 joints (cJADAS-10), with low disease activity defined as cJADAS-10 ≤2.5 with ≥1 active joint, and moderate/high disease activity defined as cJADAS-10 >2.5 3

The American College of Rheumatology conditionally recommends methotrexate as first-line DMARD therapy for polyarticular JIA, with subcutaneous administration preferred over oral route 1, 3
The American College of Rheumatology recommends adding a biologic DMARD for inadequate response to methotrexate, with combination therapy with methotrexate plus a biologic conditionally recommended over biologic monotherapy for most biologics 1, 3
Biologic options include TNF inhibitors (etanercept, adalimumab, golimumab), IL-6 receptor inhibitor (tocilizumab), and T-cell co-stimulation modulator (abatacept) 1
For sacroiliitis, TNF inhibitors are conditionally recommended as initial therapy over NSAIDs or methotrexate, with physical therapy conditionally recommended for patients with or at risk for functional limitations 4
For enthesitis, NSAIDs are conditionally recommended as initial therapy, with TNF inhibitors conditionally recommended for patients with active enthesitis despite NSAIDs, and physical therapy conditionally recommended for patients with or at risk for functional limitations 4

The primary goal is achieving low disease activity or remission to prevent joint damage and disability, with therapeutic escalation recommended to achieve low disease activity 2, 4
Regular monitoring of disease activity, functional status, and treatment-related adverse effects is essential, with treatment decisions considering patient values, preferences, and comorbidities 2

For systemic JIA, recent evidence supports IL-1 inhibitors and IL-6 receptor inhibitors as having the highest level of evidence for efficacy and safety, with high-dose glucocorticoids combined with IL-1 or IFN-γ inhibition appearing to be the best available strategy for macrophage activation syndrome (MAS) 6