Therapeutic Drug Monitoring Increases Drug Retention of Anti-Tumor Necrosis Factor Alpha Agents in Pediatric Patients With Crohn's Disease

Background: In recent years, therapeutic drug monitoring (TDM) of anti-tumor necrosis factor alpha (anti-TNF alpha) agents has been commonly utilized. We aimed to investigate its effect on long-term drug retention and clinical outcomes in pediatric patients with Crohn's disease (CD). Methods: The medical records of pediatric CD patients receiving anti-TNF alpha agents from 2007 to 2018 were reviewed retrospectively. Patients were stratified to those who initiated anti-TNF alpha treatment between 2007 and 2012, an era when TDM was not available (TDM-), and patients who initiated anti-TNF alpha treatment between 2013 and 2018, with at least 1 TDM during firstline anti-TNF alpha treatment (TDM+). The main outcome measures included time to first anti-TNF alpha discontinuation (drug retention), flares, and hospitalizations per year of first anti-TNF alpha treatment, treatment intensification rate, and surgical resection rate. Results: One hundred ninety-seven patients were included (n = 98, TDM-; n = 99, TDM+; median [interquartile range] age, 12.6 [10.1-14.2] years; females 68 [35%]). Compared with the TDM- group, the TDM+ group had a longer drug retention time (mean +/- SE, 45.0 +/- 2.7 vs 33.5 +/- 2.4 months; P = 0.001), lower hospitalization rate per patient per year (mean +/- SE, 0.51 +/- 0.7 vs 0.92 +/- 0.81; P < 0.001), and higher treatment intensification rate (70% vs 18%; P < 0.001). Surgical resection rate was not significantly different. Analysis of the entire cohort showed a longer retention time for adalimumab vs infliximab (45.3 +/- 2.8 vs 34.8 +/- 2.5 months; P = 0.007). Conclusions: TDM-based treatment enables longer drug retention time, reflecting better utilization of anti-TNF alpha agents, with several additional favorable outcomes.