A comprehensive analysis of infliximab biosimilar adoption in pediatric inflammatory bowel disease (IBD) reveals a gradual but significant shift in prescribing patterns, with biosimilar initiation rising from 1% in 2018 to nearly 42% by 2023. The study, published in Children, represents the first large multicenter cohort study to evaluate infliximab biosimilar initiation specifically in pediatric IBD patients.
The retrospective analysis examined data from 4,602 pediatric IBD patients across 73 centers within the ImproveCareNow (ICN) Network, a multicenter pediatric IBD quality improvement collaborative. The study population was 45% female with a median age of infliximab initiation of 13.7 years, and approximately 70% had Crohn's disease while 25% had ulcerative colitis.
Slow but Steady Adoption Pattern
Despite infliximab biosimilars entering the US market in November 2016, uptake was initially minimal. No patients received biosimilars in 2016, and only one patient was started on a biosimilar in 2017. The percentage of patients starting on infliximab biosimilars then increased steadily from 1% of infliximab initiators in 2018 to nearly 42% in 2023.
Among the available biosimilars, infliximab-dyyb (Inflectra) was the most commonly prescribed, outpacing the use of other biosimilar options including infliximab-abda and infliximab-axxq.
From 2016 to 2023, a total of 3,807 patients were started on infliximab originator while 795 patients were initiated on an infliximab biosimilar. The researchers found no clinically significant differences between the two patient populations in terms of demographics or disease characteristics.
Limited Impact of Demographics on Biosimilar Use
The analysis revealed minimal differences in biosimilar initiation based on patient demographics. There were no consistent differences in infliximab biosimilar initiation by age, race, or ethnicity throughout the study period, with only isolated exceptions in 2020.
In 2020, there was a statistically significant difference in biosimilar initiation based on age groups, with patients under 6 years old having the highest percentage of biosimilar initiation and those over 18 years old having the lowest. However, this finding was likely driven by the small sample size of only 17 patients under 6 years old that year.
Similarly, 2020 was the only year showing a significant difference by race, with patients categorized as "other" having higher biosimilar usage than Black or White patients. By 2021, these demographic differences had disappeared, suggesting they were anomalous rather than systematic.
Regional Disparities Emerge
The study identified notable regional variations in biosimilar adoption patterns. The Midwest, West, and Southwest regions consistently demonstrated higher infliximab biosimilar initiation rates compared to the Northeast and Southeast regions from 2020 through 2023.
These regional differences persisted throughout the later years of the study period, suggesting that factors such as institutional acceptance of biosimilars and state insurance policies may influence prescribing patterns across different geographic areas.
Center-Level Adoption Patterns
The number of ICN centers using biosimilars increased dramatically over the study period. Initially, only one center (1.9%) used an infliximab biosimilar in 2016, rising to five centers (8.2%) in 2018. From 2019 to 2023, the percentage of centers using biosimilars increased from 38.2% to 88.1%.
By 2023, 59 centers were prescribing biosimilars, while only eight centers (12%) never recorded prescribing an infliximab biosimilar throughout the entire study period. The number of centers with fewer than 10% of patients starting on biosimilars continued to decrease, dropping to nine centers (13.4%) by 2023.
Conversely, the number of centers with moderate to high biosimilar adoption increased substantially. Centers with 25-69% of patients starting on biosimilars grew from 11 centers (16.2%) in 2019 to 35 centers (52.2%) in 2023, while those with 70-100% adoption increased from 3 centers (4.4%) to 19 centers (28.4%) over the same period.
Barriers to Adoption
The researchers noted that the exact reasons for initially slow biosimilar adoption among ICN centers remain unclear. Previous surveys have identified several factors contributing to hesitancy among pediatric gastroenterologists, including preference for originator drugs, uncertainty about biosimilar efficacy, discomfort with prescribing biosimilars, and lack of awareness about institutional formulary status.
A 2021 survey found that 21% of pediatric gastroenterologists were not prescribing anti-TNF biosimilars, with respondents indicating that additional education and pediatric-specific data would increase their comfort level with biosimilar prescribing.
Clinical and Economic Implications
The study's findings have significant implications for pediatric IBD care. Access to FDA-approved treatments for pediatric IBD remains substantially limited, as anti-TNF medications are currently the only class of drugs approved for children with IBD, despite multiple therapeutic options being available for adults.
Infliximab biosimilars have demonstrated similar efficacy and safety to the originator drug in both adult and pediatric populations with IBD. The continued underutilization of biosimilars represents a missed opportunity for cost savings, as biosimilars were initially priced 10-50% less than the originator drug.
The researchers emphasized that avoiding infliximab biosimilar use is associated with increased healthcare costs, making broader adoption particularly important for healthcare systems and patients.
Study Limitations and Strengths
The study acknowledged several limitations, including potential bias from differences in how centers consented patients and recorded infliximab product types. The real-world nature of data capture meant accuracy could not be independently verified, and missing race (8%) and ethnicity (4.6%) data may have affected disparity analyses.
Additionally, insurance information was recorded only at diagnosis rather than at infliximab initiation, limiting the ability to assess insurance impact on biosimilar prescribing patterns.
Despite these limitations, the study's strengths include prospective data collection by clinicians and representation of one of the largest pediatric IBD registries, encompassing both large academic medical centers and smaller hospital-based and private practices.
The overall cumulative rate of biosimilar initiation from 2016 to 2023 was 17.3%, reflecting the gradual nature of adoption in pediatric IBD care. The researchers concluded that while infliximab biosimilar initiation has increased substantially, significant variation persists among centers, with regional differences but minimal impact from patient demographic factors.
