Real-world use of therapeutic drug monitoring of CT-P13 in patients with inflammatory bowel disease: A 12-month prospective observational cohort study

•In a real-world setting, therapeutic drug monitoring of CT-P13 was applied in 70.7% of patients.•Therapeutic drug monitoring of infliximab was collected in a proactive approach in two-thirds of patients.•The presence of anti-CT-P13 antibody was observed in 15.9% of patients with a drug-sensitive assay.•The presence of ACA was associated with a lower rate of CT-P13 trough concentration. Whether therapeutic drug monitoring (TDM) of infliximab should be implemented in daily practice is an ongoing controversy. To assess the real-world use of TDM in an observational multicentre cohort study with consecutive patients with inflammatory bowel disease (IBD) treated with CT-P13. Between September 2015 and December 2016, 364 patients with IBD were treated with CT-P13 in 13 gastroenterology departments and were followed up for 54 weeks. Disease activity, CT-P13 trough concentration and anti-CT-P13 antibody (ACA) were recorded. Steroid-free clinical remission rates at week 54 were 67.0% and 56.4% in patients with CD and UC, respectively. CT-P13 trough concentrations were measured in 70.7% of the patients. The mean CT-P13 trough concentration was 4.2±4.3μg/mL. The presence of ACA was observed in 53 (15.9%) patients. CT-P13 trough concentration was collected in a proactive approach in 62.8% of cases and in a reactive approach in 37.2%. Among patients who submitted to TDM, CT-P13 therapy was optimized in 88.7% of the reactive group and in 22.5% of the proactive group (P