Background Rapid infliximab (IFX) infusions have shown to be safe in adults with inflammatory bowel disease (IBD), but data on its safety in paediatric IBD is limited. This study aimed to assess the frequency and timing of infusion reactions (IR) in children with IBD who received rapid (1-h) vs. standard (2-h) IFX infusions. Methods This retrospective cohort study included IBD patients 4-18 years old, treated with IFX between January 2006 - November 2021 at two tertiary centres (AMC and VUmc) in Amsterdam, the Netherlands. The AMC protocol was adjusted from standard to rapid infusions with a 1-h post-infusion observation period in July 2019, whereas in VUmc only standard infusions were administered without a post-infusion observation period. After merging both departments in 2022, VUmc patients were allocated from standard to rapid infusions. The primary outcome was the frequency of acute IR amongst rapid vs. standard infusions. Secondary outcomes were the timing, severity and management of IR. Results Totally, 297 (150 VUmc, 147 AMC) patients (221 Crohn’s disease; 65 ulcerative colitis; 11 IBD-unclassified) were included, with a total of 7500 maintenance IFX-infusions. No differences were found in the frequency of IR between the patients receiving standard infusions (16/115, 13.9% of patients), rapid infusions (1/31, 3.2%) and both infusion rates (11/151, 7.3%) (p= 0.105). No difference in the frequency of IR was found between standard infusions (26/4383, 0.6% of infusions) and rapid infusions (9/3117, 0.3%) (p= 0.083). Twenty-six of 35 IR (74.3%) occurred during infusion, while nine occurred post-infusion (25.7%). All post-infusion IR were mild, requiring no intervention or oral medication. Conclusion Rapid IFX infusions did not result in an increased frequency of IR compared to standard infusions. The IR that occurred post-infusion were mild. Our data have resulted in adjustment of the protocol to rapid infusion without a post-infusion observation period for all IFX patients.

Objectives: Accelerated infliximab (IFX) infusions have shown to be safe in adults with inflammatory bowel disease (IBD), but data on its safety in pediatric IBD is limited. This study aimed to assess the incidence and timing of infusion reactions (IR) in children with IBD who received accelerated (1-h) versus standard (2-h) IFX infusions. Methods: This retrospective cohort study included IBD patients 4–18 years of age and initiated IFX between January 2006 and November 2021 at Amsterdam University Medical Centre, location Academic Medical Centre (AMC) and VU Medical Centre (VUmc). The AMC protocol was adjusted in July 2019 from standard to accelerated infusions with 1-h intrahospital post-infusion observation period, whereas in VUmc only standard infusions were administered without an observation period. After merging the departments in 2022, all VUmc patients were allocated to the accelerated infusions (AMC) protocol. Primary outcome was the incidence of acute IR among maintenance accelerated versus standard infusions. Results: Totally, 297 (150 VUmc, 147 AMC) patients (221 Crohn disease; 65 ulcerative colitis; 11 IBD-unclassified) with cumulative n = 8381 IFX infusions were included. No statistically significant difference in the per-infusion incidence of IR was observed between maintenance standard infusions (26/4383, 0.6% of infusions) and accelerated infusions (9/3117, 0.3%) (P = 0.33). Twenty-six of 35 IR (74%) occurred during the infusion, while 9 occurred post-infusion (26%). Only 3 of 9 IR developed in the intrahospital observation period following the switch to accelerated infusions. All post-infusion IR were mild, requiring no intervention or only oral medication. Conclusions: Accelerated IFX infusion without a post-infusion observation period for children with IBD seems a safe approach.