Fecal calprotectin as a predictor of abnormal colonic histology

PURPOSE: Gastroenterologists have been seeking reliable noninvasive indices of inflammatory and malignant bowel disease. This prospective study was to assess the value of fecal calprotectin in predicting abnormal histologic findings in patients undergoing colonoscopy. METHODS: Stool specimens supplied before colonoscopy by 72 consecutive patients were measured for calprotectin levels, and the findings correlated with the colonoscopy results and other fecal and blood parameters. Receiver operating characteristics curve analysis was used to determine the predictive value of fecal calprotectin for abnormal colonic histology. RESULTS: Patients with abnormal histologic findings had significantly higher calprotectin levels (218 +/- 125 mg percent) than patients with normal colonoscopy (77 +/- 100 mg percent). There was a highly significant correlation between calprotectin levels and erythrocyte sedimentation rate (r=0.45, P=0.008), positive fecal occult blood test (r=0.57, P=0.0001), and abnormal colonic histology (r=0.54, P=0.0001). Patients with active inflammatory bowel disease had higher calprotectin levels than the rest of the study patients (r=0.3; P=0.01). On multivariate analysis, calprotectin was a significant predictor of abnormal colonic histology (P=0.005; odds ratio, 1.007; 95 percent confidence interval, 1.002-1.012). The area under the receiver operating characteristics curve was 0.79. A fecal calprotectin concentration of 150 mu g/ml had a sensitivity of 75 percent, specificity of 84 percent, positive predictive value of 80 percent, and negative predictive value of 75 percent in predicting abnormal colonic histology. CONCLUSIONS: Fecal calprotectin may serve as a simple, noninvasive surrogate marker of abnormal histologic findings in patients scheduled for colonoscopy.