Effect of Time to Start of Biologic Therapy on Treatment Response in Childhood Arthritis: Results From the UCAN CAN‐DU Cohort

OBJECTIVE: To estimate the effect of time from symptom onset to start of biologic treatment on achieving inactive arthritis within six months in a cohort of patients with juvenile idiopathic arthritis (JIA). METHODS: The international UCAN CAN-DU study prospectively enrolled patients with JIA across Canada and the Netherlands. A nested cohort study was performed and biologic-naive patients with nonsystemic JIA were included at the start of biologic therapy. The primary outcome was inactive arthritis at six months. Demographics, disease-related parameters, and treatment response were compared using (non)parametric tests among early (time symptom onset to biologic start: 0-6 months), intermediate (7-12 months), and late (13-24 months) treatment groups. A logistic regression model analyzed the effect of time to biologic start on the response at six months, adjusting for active joint count and physician global assessment. A graphical representation of the model was created. RESULTS: One hundred and thirty children with JIA were included (early: n = 35; intermediate: n = 46; late: n = 49), 66% were female, and the median age at symptom onset was 11.0 years. The proportion of patients that reach inactive arthritis in the early starters (83%) was significantly higher than in late starters (57%). For each month of delay to the start of biologic treatment, the adjusted odds of having active arthritis after six months of therapy was 1.09 (interquartile range: 1.02-1.17, P = 0.009). CONCLUSION: Early start of biologic therapies in patients with JIA was associated with a higher proportion of patients reaching inactive arthritis within six months, suggesting a window of opportunity to control disease activity.