Work

Monitoring Serum Infliximab Levels in Crohn's Disease Patients: Comparison Between Two Tests

Year: 2024

Type: article

Abstract: Introduction The treatment of Crohn's disease (CD) has increasingly relied on the use of biological agents. Safe and accessible tests have led to the active implementation of therapeutic drug monitoring in clinical practice. Several commercially available assays exist to detect serum levels of infliximab (IFX). Understanding and comparing the different methods of serum IFX level measurement is important for clinical practice. Objective To compare two distinct tests for detecting serum IFX levels in patients with Crohn's disease (CD). Method This is a prospective, observational, cross-sectional study. Seventy-five patients receiving maintenance therapy with IFX, aged between 18 and 60 years, were selected. Participants were allocated into the disease activity (CDA) or remission (CDR) groups. Disease activity was defined by endoscopic or radiological criteria. Serum IFX levels were measured by enzyme-linked immunosorbent assay (ELISA) and lateral flow rapid test. Differences between test results within the measurement range were evaluated by the Wilcoxon test, Passing-Bablok regression, and Bland-Altman method. Results A significant difference was observed (p< 0.001) in the median results between the two tests (2.27 for Promonitor [IQR: 1.36–4.27] vs. 4.0 for Quantum Blue [IQR: 1.7–6.9]). The CUSUM test showed a linear relationship between the two measures, making the Passing-Bablok method applicable (p > 0.20). The serum IFX concentrations, within the measurement range, assessed in 27 patients with CD for each method, showed higher values for the rapid test than for ELISA. The two IFX level tests had moderate agreement (r = -0.6758; p < 0.001). The Passing-Bablok regression intercept did not significantly differ from 0 (-0.018; 95% CI -0.489 to 0.420), but the slope was less than 1 (0.589; 95% CI 0.454 to 0.766), indicating a proportional difference between the two tests. Additionally, a Bland-Altman test was performed to further compare and establish the level of agreement between the two assays. This analysis revealed moderate agreement between the two assays, with only one value outside the confidence interval. Conclusion Although the tests showed a statistically significant association, they cannot be considered interchangeable, especially at higher IFX levels. Therefore, it is ideal for patients to be monitored using the same assay. Publication History Article published online: 25 April 2025 © 2025. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution 4.0 International License, permitting copying and reproduction so long as the original work is given appropriate credit (https://creativecommons.org/licenses/by/4.0/) Thieme Revinter Publicações Ltda. Rua do Matoso 170, Rio de Janeiro, RJ, CEP 20270-135, Brazil

Source: Journal of Coloproctology

DOI: 10.1055/s-0045-1808724