Infliximab serum concentrations in luminal Crohn's Disease and its relationship with disease activity: a multicentric cross-sectional study.

OBJECTIVES: In Latin America, experience with monitoring serum Infliximab (IFX) concentrations is scarce. Our study aimed to compare IFX serum concentrations between patients with active disease or in remission.

PATIENTS AND METHODS: A cross-sectional study was performed in patients with luminal Crohn's disease (CD) during maintenance treatment with IFX. Patients were classified as in remission or disease activity according to clinical scores and endoscopic, radiological, and laboratory markers. A comparison of IFX trough levels between the two groups was performed.

RESULTS: 80 CD patients were included [41 (51%) in remission and 39 (49%) with active disease]. In the analysis of general disease activity, the median serum levels of IFX in patients with remission and with active CD were 5.63 [0.03 - 14.40] vs. 3.84 [0.03 - 14.40] (p = 0.287). Furthermore, there was no difference in serum IFX concentrations in endoscopic, radiological, and laboratory activities. Only in the clinical evaluation was there a significant difference between the IFX median serum levels between patients in remission and disease activity, 5.63 [0.03 - 14.40] vs. 2.14 [0.32 - 10.54] (p = 0.042).

CONCLUSIONS: IFX serum concentrations during maintenance treatment were similar in patients with luminal CD in remission and general, endoscopic, radiological, and laboratory disease activity. Patients with clinically active disease had lower IFX concentrations than patients in remission.