Systemic-onset juvenile idiopathic arthritis
ICD-10 M08 · ICD-11 FA24.4

Systemic JIA in Patients Under 18 Without MAS: What to Do When Initial Monotherapy Has Not Resolved Systemic Features

This protocol applies to systemic juvenile idiopathic arthritis in patients under 18 years of age, without macrophage activation syndrome. Systemic JIA is distinct from all other categories of JIA due to fever, rash, and visceral involvement, and is considered by some to be an autoinflammatory disorder.

Previous line — goal not reached

Initial monotherapy — an NSAID trial or a biologic agent as first-line treatment — did not achieve resolution of systemic features including fever and rash. This protocol defines the structured next step after that inadequate response or intolerance.

Next-step approach (partial overview)

When the initial agent has not controlled systemic disease activity, the approach involves an alternative IL-1 or IL-6 inhibitor, with the option to switch between agents in this class as needed based on response or tolerability.

Goals: Resolution of systemic signs and inactive disease. The complete protocol specifies which agents, under what conditions, and in what sequence — see the full regimen for details.

References

DOI: 10.1002/art.42037

Systemic JIA is distinct from all other categories of JIA due to fever, rash, and visceral involvement and is considered by some to be an autoinflammatory disorder.

Biologic DMARDS (IL-1 and IL-6 inhibitors) are conditionally recommended as initial monotherapy for systemic JIA without MAS.

IL-1 and IL-6 inhibitors are strongly recommended over a single or combination of csDMARDs for inadequate response to or intolerance of NSAIDs and/or glucocorticoids for systemic JIA without MAS.

As response to individual agents is variable, switching among and between IL-1 and IL-6 inhibitors when needed due to lack of efficacy or poor tolerability is appropriate.

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