Mucosal Healing and Long-term Outcomes of Patients With Inflammatory Bowel Diseases Receiving Clinic-Based vs Trough Concentration-Based Dosing of Infliximab.

Background & Aims: The Trough Concentration Adapted Infliximab Treatment (TAXIT) trial demonstrated that maintaining infliximab trough concentrations at 3 to 7 μg/mL is most effective at inducing remission in patients with inflammatory bowel diseases (IBDs), with fewer flares than clinic-based dosing. We performed a follow-up analysis of study participants to explore the correlation between trough dosing strategy and mucosal healing, continued infliximab use, and rates of hospitalization, surgery, and steroid use.

Methods: This was a retrospective single-center study of 226 patients with IBD who completed the maintenance phase of TAXIT, performed at the University Hospitals of Leuven in Belgium. Baseline patient characteristics, laboratory test results, and endoscopic data were obtained at the end of that study between June 2012 and December 2013 (n = 125). Long-term outcome data (IBD-related hospitalization, abdominal surgery, and systemic steroid use) were collected from the time of the last TAXIT study visit (August 2012-April 2013) until April 1, 2016. We also collected data on continued use of infliximab and trough concentrations.

Results: At baseline, 91% of patients in the clinic-based dosing group and 90% of patients in the trough concentration-based dosing group had mucosal healing. After a median follow-up time of 41 months (interquartile range, 39-42 mo), infliximab treatment was continued by 81 of 108 patients (75%) from the clinic-based dosing group and 86 of 107 (80%) from the trough concentration-based dosing group. However, within 1 year, infliximab was discontinued by 10 of 27 patients (37%) from the clinic-based dosing group and 2 of 21 patients (10%) from the trough concentration-based dosing group (P = .04). The rates of hospitalization, surgery, and steroid use were below 15% in both groups.

Conclusions: At the end of a trial of clinic-based dosing vs trough concentration-based dosing of infliximab in patients with IBD, most patients had mucosal healing. Most patients (≥75%) in both groups continued taking infliximab for more than 3 years after the trial, but a significantly higher proportion of patients in the clinic-based dosing group discontinued infliximab in the first year after the end of the trial. Both groups had low rates of hospitalization, surgery, and steroid use.