Blood eosinophilia in patients with inflammatory bowel disease losing response to biologics

Emerging data suggest that blood eosinophilia may be linked to inflammatory bowel disease (IBD) activity and biologic treatment failure. This study assessed the occurrence of eosinophilia in IBD patients experiencing biologic failure.

This was a single-center retrospective study of IBD patients treated with infliximab (IFX) or vedolizumab (VDZ) between 2017 and 2023. Demographics, disease characteristics, disease activity, treatment modifications, together with data on blood eosinophilia and persistent blood eosinophilia, were recorded at 1-year follow up following treatment initiation with biologics. The outcomes were rate of biologic failure, hospitalizations, and surgery at 1 year. Uni- and multivariate analyses were performed to identify factors associated with these outcomes.

The study included 154 patients, 96 with Crohn's disease (CD) (62.3%) and 58 with ulcerative colitis (UC) (37.7%). The occurrence of blood eosinophilia was observed in 22% of patients over 1 year of followup. In univariate analysis, factors associated with biologic failure included previous biologic exposure (P<0.001), baseline immunosuppressants (P=0.009), baseline perinuclear antineutrophil cytoplasmic antibody (P=0.041), and blood eosinophilia (P=0.037). Blood eosinophilia was associated with a higher risk of VDZ failure (odds ratio [OR] 2.81, 95% confidence interval [CI] 1.01-8.10; P=0.047) and was more frequently observed in patients with CD than in UC (OR 2.97, 95%CI 1.05-8.91; P=0.040). Multivariate analysis confirmed the association of blood eosinophilia and biologic failure (OR 2.65, 95%CI 1.08-6.65; P=0.034).

Blood eosinophilia was independently associated with biologic failure at 1 year in IBD patients and may represent a risk-stratifying biomarker.