Subclinical Persistent Inflammation as Risk Factor for Crohn's Disease Progression: Findings From a Prospective Real-World Study of 2 Years

Subclinical intestinal inflammation is common in Crohn’s disease (CD). We aimed to explore its impact in the disease progression of infliximab-treated patients and the usefulness of fecal calprotectin (FC) and C-reactive protein (CRP) as surrogate minimally invasive biomarkers. The registry-based, prospective, observational, multicenter DIRECT (study to investigate the correlation of fecal calprotectin with serum Drug levels and development of an antI-dRug antibodiEs among adult patients with inflammatory bowel disease reCeiving anti-TNF-alfa treatment or vedoluzimab treatment) study followed infliximab-treated CD patients for 2 years in a tertiary care setting. Persistent inflammation definition was based on FC (>150 μg/g, >250 μg/g, or >350 μg/g) or serum CRP (>3 μg/mL) concentrations over 2 consecutive or at least 3 visits. Patients were categorized according to a composite outcome reflecting disease progression that incorporated surgery; hospitalizations; new fistulae, abscess, or stricture; and treatment escalation. Of 322 DIRECT study patients, 180 asymptomatic, infliximab treated on maintenance regimen were included in the analysis. Patients developing the composite endpoint (n = 96) presented higher median levels of FC (205 [interquartile range, 98–515] μg/g; P = .045) but not of CRP (2.50 [interquartile range, 0.80–6.00] μg/mL; P = .895). Biomarker-defined persistent subclinical inflammation prevalence ranged from 24% to 81%. Considering FC >250 μg/g in 2 consecutive visits, prevalence was 50%, odds of achieving the endpoint were increased 3-fold (odds ratio, 2.996 [95% confidence interval, 1.557–5.776]), and time-to-outcome occurrence was significantly lower among subjects with persistent inflammation (median time: 11 months). Both clinical-related and treatment-related components were significantly associated with persistent inflammation. Definitions based on CRP >3 μg/mL, FC >150 μg/g, FC >350 μg/g, double biomarkers (FC >250 μg/g and/or CRP >3 μg/mL), or more visits did not improve predictive ability. Persistent inflammation, defined simply and readily by FC >250 μg/g over 2 consecutive visits, was associated with a significantly higher risk and shorter time to occurrence of a composite outcome reflecting disease progression in asymptomatic infliximab-treated CD patients.