Diagnostic Work-Up of Inflammatory Bowel Disease in Children: The Role of Calprotectin Assay

Background: Some reports highlight the potential application of fecal calprotectin as a direct biomarker of intestinal inflammation and, therefore, as support in choosing candidates for endoscopy. The value of 100 mcg/g was recently assumed as the best cutoff for this assay. The purpose of this study was to assess the diagnostic precision of the fecal calprotectin assay, compared to histology, as a stool-screening biomarker for inflammatory bowel disease (IBD) among a group of prospectively identified patients referred for recurrent abdominal pain and altered bowel habits. Methods: Between 1999 and 2007 we prospectively evaluated the calprotectin assay in a cohort of patients with recurrent abdominal pain and altered bowel habits associated or not with other symptoms suggestive of IBD. All patients suspected of IBD, according to Rome and Porto criteria, provided stool specimens for the calprotectin assay and subsequently underwent endoscopic procedures. Results: Compared to histology, the cutoff of 100 mcg/g reached a sensitivity and specificity of 100% and 68%, respectively, and a likelihood ratio (LR) of 3.1. The cutoff value of 160 mcg/g, however, in our series produced the best joint estimate of sensitivity and specificity: 100% and 80%, respectively, with an LR of 5. Conclusions: In pediatric patients with recurrent abdominal pain and changes in stool habits, a positive calprotectin assay is closely associated with IBD; its systematic employment, therefore, seems to improve the process of endoscopy referral. This test, simple and inexpensive, could be included in the first non-invasive phase of an IBD diagnostic work-up. (published online ahead of print March 22, 2010. Inflamm Bowel Dis.)