Correlation between fecal calprotectin and inflammation in the surgical specimen of Crohn's disease.

Background: An accurate assessment of the inflammatory activity is crucial to establish the most appropriate treatment in Crohn's disease (CD). The present study aimed to evaluate the utility of preoperative fecal calprotectin (FC) measurement in small bowel CD and its relationship with inflammatory activity in surgical pathology specimens.

Methods: This was a prospective observational study including all the patients with small bowel CD operated on at our center between March 2011 and September 2013. Preoperative laboratory and stool tests were performed. A meticulous exploration of entire small bowel was performed during surgery, and the resected bowel (or a sample of whole intestinal wall, if strictureplasty) was submitted for pathologic analyses. Chiorean's score was used to grade pathologic features (inflammation or fibrosis). In case of multiple lesions, the most inflammatory component was considered.

Results: Thirty-eight consecutive patients were included in the study, and 81 small bowel lesions were identified. Among inflammatory markers, only FC was significantly associated with the degree of histologic inflammation in the surgical specimen (P < 0.003). FC reflected histologic inflammatory activity with an area under the receiver-operating characteristic curve of 0.85 (CI: 0.70-0.99; P < 0.001). A cutoff value of 170 μg/g had 81% sensitivity and 85% specificity for diagnosis of moderate or severe inflammation. Ordinal regression analysis showed the probability of a greater or lesser degree of inflammation based on the value of preoperative FC.

Conclusions: FC is an excellent biomarker of inflammatory activity in small bowel CD as it correlates with histologic inflammation in the surgical specimen.