Authors Afroditi Orfanidou, Konstantinos Katsanos, Theodoros Voulgaris, Aristeidis Kofinas, Maria Veatriki Christodoulou, Maria Konstandi, Dimitrios Christodoulou.

Background Infliximab monitoring correlates with improved outcomes in inflammatory bowel disease (IBD). We aimed to evaluate the association between serum infliximab trough levels (TLs) and therapeutic outcomes in Greek patients with Crohn’s disease (CD) or ulcerative colitis (UC).

Methods This cross-sectional study included consecutive adult patients with IBD receiving intravenous infliximab maintenance therapy at a Greek tertiary center. Therapeutic outcomes assessed were clinical remission (CR), steroid-free clinical remission (SFCR), biochemical remission (BR: C-reactive protein <5 mg/L), and combined (steroid-free and biochemical) remission (SFCBR).

Results Seventy-seven patients participated (62.3% with CD, 16.8% on concomitant immunomodulators), with a mean infliximab infusion duration of 5.1±4.6 years. Forty-seven (61%) patients underwent treatment escalation. Infliximab mean TLs were 7.2±4.9 μg/mL, correlating only with treatment escalation (9.7 vs. 3.6 μg/mL, P<0.001). CR was achieved in 88.3% of patients, SFCR in 80.5%, BR in 62.3%, and SFCBR in 55.8%. In a subgroup analysis, for patients without treatment escalation, higher mean TLs were significantly associated with BR (4.2 vs. 0.8
μg/mL, P=0.020) and SFCBR (4.3 vs. 1.5 μg/mL, P=0.035). In receiver operating characteristic analysis, TLs predicted SFCBR (P=0.016) with good accuracy (area under the curve [AUC] 0.768, 95% confidence interval [CI] 0.584-0.952), with an optimal TL cutoff at 3.4 μg/mL. For patients with treatment escalation, TLs predicted SFCBR (P=0.018) with fair accuracy (AUC 0.653, 95%CI 0.527-0.755), with an optimal TL cutoff at 11 μg/mL.

Conclusions Infliximab TLs correlate with treatment escalation. Higher infliximab TLs may predict combined remission among patients with treatment escalation.

Keywords Inflammatory bowel disease, infliximab monitoring, infliximab trough levels, treatment intensification, treatment escalation

Ann Gastroenterol 2024; 37 (6): 674-681