Incidence, Risk Factors and Management of Adverse Events in Contemporary Real‐World Care of Children with Juvenile Idiopathic Arthritis

OBJECTIVE: We describe the frequency, risk factors, severity, and management of actionable and serious adverse events (AAE and SAE) in children with newly diagnosed Juvenile Idiopathic Arthritis (JIA) in Canada. METHODS: We enrolled patients within 3 months of JIA diagnosis in the Canadian Alliance of Pediatric Rheumatology Investigators (CAPRI) Registry, an ongoing prospective registry-based cohort study. At every clinic visit, clinicians reported AAEs since the previous visit, their severity and actions undertaken. We calculated proportion of patients and visits with an event, events rates per 100 patient-years (PY), and used Kaplan-Meir and Cox regression analysis to estimate first AAE risk and assess associated risk factors. RESULTS: Among 964 patients followed for 2,046 PY, AAEs occurred in 39.0% of patients (34.9 per 100PY) and SAEs in 3.4% (2.0 per 100PY). Gastrointestinal symptoms linked to non-steroidal anti-inflammatory drugs (NSAID) and methotrexate (MTX) were most common (56.4%). In adjusted analyses, active disease, subcutaneous MTX (HR 3.27, p<0.001), oral MTX (HR 2.08, p<0.001), and NSAID (HR 2.17, p<0.001) were associated with increased AAE risk, while biologic Disease Modifying Anti-Rheumatic Drugs (bDMARDs) were associated with decreased risk (HR 0.46, p<0.001). Forty SAEs occurred, including 16 infections with hospitalization and one malignancy, mostly in patients not receiving bDMARDs. There were no deaths, demyelinating conditions, or opportunistic infections. CONCLUSION: In this real-practice JIA cohort, AAEs were reported in 2 of 5 patients and most were mild events related to NSAID and MTX. SAEs were rare with no deaths and few major complications.