Risk of Infections With Infliximab vs Adalimumab Among Children With Inflammatory Bowel Disease.

Importance: Infliximab and adalimumab are the only biologics approved by the US Food and Drug Administration for use in children with inflammatory bowel disease (IBD). The comparative infection risks between infliximab and adalimumab have not been evaluated in clinical settings. Objective: To compare the risk of infections with infliximab vs adalimumab among pediatric patients with IBD using nationwide claims data. Design, Setting, and Participants: This cohort study used data from 2 nationwide health care claims databases from January 1, 2016, to February 28, 2025. The study included children and adolescents aged 6 to 17 years with a diagnosis of Crohn disease or ulcerative colitis who newly initiated infliximab or adalimumab and had 180 days or more of prior continuous enrollment. Exposures: Initiation of adalimumab vs infliximab. Main Outcomes and Measures: Serious infections were defined as infections requiring hospitalization, using a validated algorithm. Outpatient infections were defined as an outpatient infection diagnosis with a targeted antimicrobial dispensed within 1 day. Baseline covariates within each dataset were balanced with 1:1 propensity score matching and results were pooled using fixed effects meta-analysis. Incidence rates and hazard ratios (HRs) were estimated over a 180-day follow-up. Results: After applying exclusion criteria, 4239 children with IBD initiating infliximab (2467; mean [SD] age, 13.3 [2.9] years; 1462 boys [59.3%]; 1502 with Crohn disease [60.9%]) or adalimumab (1772; mean [SD] age, 14.0 [2.7] years; 1047 boys [59.1%]; 1068 with Crohn disease [60.3%]) were identified. After matching, each exposure group included 1533 patients. The incidence of serious infections was 29 per 1000 person-years for infliximab (reference) and 34 per 1000 person-years for adalimumab (pooled HR, 1.15; 95% CI, 0.63-2.11). Outpatient infections were more common, with rates of 358 per 1000 person-years for infliximab and 386 per 1000 person-years for adalimumab (pooled HR, 1.08; 95% CI, 0.90-1.29). Results of sensitivity analyses, including restriction to monotherapy, originator-only use, first-line users only, exclusion of gastrointestinal infections from the outcome, and extending follow-up to 365 days, were all consistent with the primary findings. No mycobacterial infections were observed in the overall cohort. Conclusions and Relevance: In this cohort study of children and adolescents with IBD, serious infections were rare. No evidence of differences in infection risk were observed between infliximab and adalimumab. These findings suggest that the 2 agents may have comparable infection risk profiles in pediatric IBD, although meaningful differences cannot be ruled out.