Fecal calprotectin as an inflammatory biomarker in small bowel Crohn disease

Small bowel capsule endoscopy (SBCE) is an essential tool for evaluation of small bowel (SB) Crohn disease (CD). Fecal calprotectin (FC) represents an important biomarker of intestinal inflammation, widely used in ulcerative colitis and CD. Our aim was to evaluate the role of FC for diagnosing inflammatory activity in patients with isolated SB CD and how it correlates with SBCE findings.

This is a retrospective study conducted in a tertiary inflammatory bowel disease referral center that included patients with SB CD who underwent SBCE between January 2017 and February 2023. FC value was obtained from the closest stool examination to SBCE.

One hundred ninety-six patients were included: 123 were women (63%) with a mean age of 44.2 years. In the SBCE, 127 (65%) patients had a Lewis Score ≥135 and, among the 94 patients with FC >200 μg/g, 23 had LS <135, 36 had LS between 135 and 790, and 35 had LS ≥790. FC levels were predictive of endoscopic lesions in SBCE, with significant correlation between FC level and total LS (Pearson correlation coefficient 0.43, P<.001). The sensitivity and specificity were calculated for each cut-off value being respectively 78% and 45% for FC = 100 μg/g, 69% and 59% for FC = 150 μg/g and 67% and 67% for FC = 200 μg/g.

FC showed moderate correlation with endoscopic findings in SBCE in SB CD. It is, therefore, a reasonable marker for predicting significant inflammatory lesions in SBCE; however, none of the cut-off had a high sensitivity or specificity.