Complications
Can occur with ongoing inflammation and poor disease control.
Can occur with poor disease control and lead to the need for joint replacement.
Can occur with ongoing inflammation and poor disease control, especially in systemic and polyarticular subtypes.
Can occur with ongoing inflammation and poor disease control in children with enthesitis-related JIA.
JIA-associated uveitis is one of the most devastating complications. It is predominantly chronic, anterior, non-granulomatous inflammation affecting the iris and ciliary body.
Onset of chronic uveitis is usually insidious and often asymptomatic; therefore, screening and close monitoring by a paediatric ophthalmologist with a slit lamp is essential for diagnosis. The American College of Rheumatology recommends screening every 3 months for children at high risk of uveitis, and screening every 6 to 12 months for children at lower risk.[123] High-risk features are: oligoarticular JIA, rheumatoid factor-negative polyarticular JIA, psoriatic arthritis, undifferentiated arthritis with positive antinuclear antibodies, age younger than 7 years at JIA onset, and duration of JIA 4 years or less.[123]
Further complications such as glaucoma, cataracts, band keratopathy, synechiae, and blindness may occur.
Topical corticosteroids should be used initially to treat active anterior uveitis.
Topical and systemic non-steroidal anti-inflammatory drugs should not be used alone to treat active anterior uveitis.
Systemic immunosuppression is recommended if inactivity is not achieved within 3 months or inflammation is reactivating during corticosteroid dose reduction. Systemic immunosuppression in active uveitis is recommended if poor prognostic factors (uveitis antedating arthritis, posterior synechia, male sex, band keratopathy, glaucoma and cataract, poor initial vision, hypotony, macular oedema, and dense vitreous body opacification) are present at the first visit. Lack of remission later on during the disease course also requires systemic immunosuppression.[124]
Methotrexate is the first choice for systemic immunosuppression. If methotrexate is ineffective or not tolerated, adding or switching to biological treatment is recommended. The use of anti-tumour necrosis factor treatment strategies is recommended in patients with uveitis refractory/resistant to disease-modifying antirheumatic drugs, principally methotrexate.[124]
MAS is a life-threatening complication of systemic-onset JIA. Signs and symptoms include persistent fever; elevated and/or rising ferritin or other markers of inflammation/damage; inappropriately low or declining haemoglobin, platelet counts or white blood cells (neutrophils and lymphocytes); hepatic dysfunction; coagulopathy; splenomegaly; central nervous system dysfunction.[96]
Laboratory abnormalities include pancytopenia, decreased erythrocyte sedimentation rate, elevated liver function tests, and disseminated intravascular coagulation-like coagulopathy. MAS is present if the following criteria are met in a febrile patient with known or suspected systemic juvenile idiopathic arthritis: ferritin >684 micrograms/L (>684 ng/mL) and any two of platelet count ≤181 x 10⁹/L, aspartate aminotransferase >48 U/L, triglycerides >1.76 mmol/L (>156 mg/dL), or fibrinogen ≤3.6 g/L (≤360 mg/dL).[98] Consult a paediatric rheumatology specialist urgently if features of MAS are present. Patients with MAS can deteriorate rapidly and may require intensive care admission. Initial treatment is with high-dose intravenous corticosteroids. The management of patients with MAS is covered in this topic's Treatment algorithm.
Highly fatal lung disease has been observed in some children with systemic JIA, the majority of whom were treated with biological therapy. Risk factors include macrophage activation syndrome (MAS), younger age with MAS, previous reactions to tocilizumab and trisomy 21. Affected children often present with acute digital clubbing.[95][125]
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