Supratherapeutic infliximab levels do not predict complications risk in CD patients

Trough levels of infliximab are not predictive of the risk of short-term infectious (IC) or noninfectious complications (NIC) in adult patients with Crohn’s disease (CD), reports a study.

A team of investigators retrospectively assessed a large cohort of CD patients who received infliximab and underwent therapeutic drug monitoring (TDM) at a tertiary inflammatory bowel disease centre between 1 January 2010 and 1 December 2019. TDM referred to the checking of infliximab trough and antibody levels within a 48-h period prior to administration.

Patients with a minimum assessment of 3 month pre- and post-TDM were included in the study. In cases of multiple TDMs, the highest trough level was considered. Participants were then assigned to four predefined trough level groups (A: <5 µg/mL; B: 5‒10 µg/mL; C: 10‒15 µg/mL; and D: ≥15 µg/mL).

The investigators compared the rates of IC and NIC during the 3-month prior and following TDM across groups. They also obtained the duration of exposure in terms of months leading to TDM to examine differences in IC and NIC rates.

A total of 342 CD patients (median age 35 years, 58 percent men) were included. IC occurred in 52 patients (15 percent) and NIC in 30 (9 percent). IC (p=0.9) and NIC rates (p=0.7) were similar across the four trough level groups.

Multivariable analysis revealed that exposure to infliximab >40 months (as determined by receiver operating characteristic curve analysis) correlated with a lower likelihood for IC (adjusted odds ratio [aOR], 0.51; p=0.04) but not NIC (aOR, 0.72; p=0.46).

These findings “support the safety of targeting higher infliximab trough levels when necessary and greater vigilance during the early stages of treatment,” the investigators said.