Fecal Calprotectin as an Inflammatory Biomarker for the Small Bowel Crohn's Disease

Abstract

Background: Small bowel capsule endoscopy is an essential tool for evaluation of ileal Crohn's disease (CD). Fecal calprotectin (FC) represents an important biomarker of intestinal inflammation, widely used in ulcerative colitis and colonic CD . Our aim was to evaluate the role of FC for diagnosing inflammatory activity in patients with isolated small bowel CD and how it correlates with SBCE findings. Methods: This is a retrospective study conducted in a tertiary inflammatory bowel disease (IBD) referral center that included patients with ileal CD that underwent SBCE between January 2017 and February 2023. FC value was obtained from the nearest stool examination to SBCE. Results: One hundred and ninety-six patients were included: 73 were men (37.2%) with a mean age of 44.2 years. In the SBCE, 127 patients had a LS ≥ 135 and, among the 94 patients with FC > 200 μg/g, 23 had LS < 135, 36 had LS between 135-790, and 35 had LS > 790. Interestingly, we found that FC levels were predictive of endoscopic lesions in SBCE, with significant correlation between FC level and total LS (Pearson correlation coefficient 0.43, p<0.001). The sensitivity and specificity were calculated for each cut off value being respectively 77.8% and 45.2% for FC=100 μg/g, 68.9% and 58.7% for FC = 150 μg/g and 66.7% and 67.6% for FC = 200 μg/g. Conclusions: FC showed moderate correlation with endoscopic findings in SBCE in ileal CD. It is therefore a reasonable marker for predicting significant inflammatory lesions in SBCE, however none of the cuf-off had a high sensitivity or specificity.