Background: Calprotectin is a calcium-binding protein that is abundantly contained in the cytoplasm of neutrophils and monocytes. It is secreted at the site of inflammation. Fecal calprotectin is a fecal biomarker used for the assessment of intestinal inflammation in patients with inflammatory bowel disease; however, the accuracy of fecal calprotectin in the evaluation of small bowel inflammation in patients with Crohn's disease (CD) is unclear. This study aimed to assess the diagnostic accuracy of fecal calprotectin to detect intestinal inflammation evaluated with small bowel balloon-assisted endoscopy (BAE) in patients with CD.
Methods: This was a cross-sectional observational study involving a total of 54 patients who underwent BAE between June 2015 and October 2016 at our institution. Endoscopic severity was evaluated with modified simple endoscopic score for CD (mSES-CD), which evaluated the ileum and jejunum in addition to the terminal ileum, colon, and rectum. The severity of inflammation in each segment was evaluated with the same endoscopic parameters (0–3 for ulcer size, ulcerated/affected surface, and stenosis) as the original SES-CD. The total score of each segment was taken as the final score. Mucosal healing was defined as an mSES-CD score of 3 or less. Fecal calprotectin level was determined with EliA Calprotectin 2.
Results: Among the 54 patients, 44 patients (83.0%) were male, 13 patients (24.1%) had past history of bowel resection, and 22 patients (41.5%) were treated with anti-TNF α reagents. Fecal calprotectin levels were significantly correlated with mSES-CD scores (r=0.589). In the receiver-operator curve analysis, the cut-off value of fecal calprotectin level was determined as 250 μg/g for mucosal healing. The sensitivity and specificity at this cut-off value to detect mucosal healing were 92.3% and 83.3% respectively. This cut-off value was also evaluated in 31 patients who had no large-bowel disease. The sensitivity and specificity to detect mucosal healing were 90.9% and 75.0% respectively in this subgroup.
Conclusions: The levels of fecal calprotectin were correlated with the endoscopic activity assessed with BAE.