Association Between Small Bowel Lesion Activity and Fecal Calprotectin in Pediatric Crohn's Disease

Background:
The widespread use of capsule endoscopy (CE) has allowed detailed evaluations of small bowel lesions in Crohn’s disease (CD). CE is a minimally invasive procedure commonly performed in children but often conducted in hospitals. Some patients have difficulty in swallowing, often requiring multiple endoscopies with capsule endoscopic assist devices. Therefore, CE cannot be performed easily on children. Markers that reflect the activity of small bowel lesions may help determine the necessity of endoscopic assessments. In adults, fecal calprotectin (Fc) is a useful marker for small bowel lesion activity. To date, its utility in children remains unexplored. This study retrospectively investigated whether Fc can effectively reflect the activity of small bowel lesions in pediatric CD by comparing it with other biomarkers.
Methods:
The study recruited children with CD, including those with suspected CD, who underwent CE at our hospital between January 2023 and August 2024. Patients with Montreal classifications of L1 and L3 were deemed eligible. Patients who had not undergone an Fc test within 3 months before or after CE, or who had undergone bowel resection were excluded. Mucosal healing was defined as a Lewis score (LS) < 135. Only children aged < 16 years were included.
Results:
Eighteen patients were analyzed; 15 (83%) were male. Nine patients had a confirmed diagnosis of CD, and 9 had a suspected diagnosis after examination. The median age at examination was 10 years (range 7-14 years). The median PCDAI was 5 points (range 0-42.5). The median LS was 135 (range 0-1200), and the median Fc was 788 mg/kg (range 0-7323 mg/kg). ROC-AUC analysis showed a strong correlation between Fc and LS at 0.86. The cut-off value for discriminating mucosal healing was 90.0 mg/kg (sensitivity, 66.7%; specificity, 100%). The AUCs of the other biomarkers correlated with white blood cells (0.57), hemoglobin (0.56), platelets (0.56), albumin (0.58), erythrocyte sedimentation rate (0.67), and CRP (0.75), all of which were lower than the AUC of Fc.
Conclusions:
Fc may be more useful than other biomarkers for assessing small bowel lesion activity in pediatric patients with CD.