August 10, 2026
3 min read
Key takeaways:
- During the initial 180 days of treatment, infection risk was similar for both therapies in children.
- Study results suggest treatment decisions consider all clinical factors, rather than just infection risk.
Infliximab and adalimumab exhibited similar infection risk profiles in children and adolescents with inflammatory bowel disease when used as initial biologic therapy, according to study results published in JAMA Network Open.
Researchers reported that serious infections were “rare” with use of either biologic, with slightly higher rates of outpatient infections.
“Infliximab and adalimumab are the only biologic therapies approved by the FDA for both Crohn’s disease and ulcerative colitis in children, and both are commonly used as initial biologic treatments,” Ning Lyu, PhD, MS, a postdoctoral researcher who focuses on pediatric pharmacoepidemiology at Harvard-MIT Center for Regulatory Science, told Healio.
More than 40% of individuals with IBD receive biologic therapy before adulthood, according to study background. However, research comparing infection risk between infliximab and adalimumab (Humira, Abbvie) in this patient population is limited.
“Because children with IBD may already be at increased risk for infection related to the underlying disease and other immunosuppressive treatments, we wanted to provide head-to-head evidence from routine clinical practice to better inform treatment decisions,” Lyu said.
Lyu and colleagues gathered data from two nationwide commercial claims databases to investigate. They identified 4,239 children and adolescents aged 6 to 17 years with CD or UC who were new users of infliximab or adalimumab between January 2016 and February 2025. Eligible children were continuously treated for at least 180 days before study entry.
Demographic characteristics were similar between those who initiated infliximab (n = 2,467; mean age, 13.3 years; 59.3% boys; 60.9% CD) or adalimumab (n = 1,772; mean age, 14 years; 59.1% boys; 60.3% CD). After propensity-score matching, 1,533 individuals were included in each treatment group.
Primary outcomes included serious infections requiring hospitalization or outpatient infections with prescription of an antimicrobial.
Follow-up continued until 180 days after cohort entry or until death, disenrollment, discontinuation of therapy or end of available data.
Incidence of outpatient infections for children taking infliximab was 358 per 1,000 person-years and 386 per 1,000 person-years for those taking adalimumab (pooled HR = 1.08; 95% CI, 0.9-1.29).
Serious infections occurred in fewer patients. Incidence was 29 per 1,000 person-years for infliximab and 34 per 1,000 person-years for adalimumab (pooled HR = 1.15; 95% CI, 0.63-2.11).
“Serious infections were uncommon,” Lyu said, “occurring in about 1% to 2% of patients, while outpatient infections occurred in about 15%.”
No mycobacterial infections occurred during the study period.
Sensitivity analyses indicated no detectable difference in infection risk between the two therapies, including when analysis was restricted to users of anti-tumor necrosis factor monotherapy, when biosimilars or those with gastrointestinal infections were excluded, and when follow-up was extended to 365 days.
Results also were consistent across subgroup analyses based on age and IBD subtype. Risk for outpatient infections was slightly elevated among children with CD taking adalimumab (HR = 1.26; 95% CI, 0.99-1.61).
“These findings suggest that infection risk alone may not distinguish between the two treatments,” Lyu said. “Clinicians can also consider disease characteristics, route of administration, treatment burden, adherence and family preference when choosing therapy.”
Study limitations include the potential for misclassified outcomes — the algorithm that identified serious infections had a positive predictive value of 80.2% — and lack of precision on estimates of serious infection subtypes. Generalizability to publicly insured patients also may be limited.
“Our findings provide some reassurance that infliximab and adalimumab have broadly similar infection safety profiles when used as initial biologic therapy in children and adolescents with IBD,” Lyu said.
“However, these treatments still require appropriate infection screening and monitoring, and our results do not show that their safety profiles are identical,” she added.
For more information:
Ning Lyu, PhD, MS, can be reached at ning_lyu@hms.harvard.edu.
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