Fecal calprotectin can be used as a noninvasive tool to assess inflammation in patients with inflammatory bowel disease (IBD). However, the diagnostic accuracy of calprotectin is modest, and therefore additional markers are needed. We compared the efficacy of fecal hemoglobin and calprotectin as markers for endoscopic inflammation in patients with IBD.
Consecutive patients with Crohn's disease or ulcerative colitis scheduled for surveillance colonoscopy collected a stool sample before bowel preparation. Experienced endoscopists assessed the presence of inflammation in each colonic segment. Fecal calprotectin and hemoglobin were analyzed with an enzyme-linked immunosorbent assay. Receiver operator characteristic statistics were used to determine cutoff values for calprotectin and hemoglobin.
A total of 176 surveillance colonoscopies were performed in 164 patients, of which 83 patients had Crohn's disease, 74 had ulcerative colitis, and 7 IBD-unclassified. Median (interquartile range) calprotectin and hemoglobin concentrations were 137 mg/kg (interquartile range, 33–494) and 0.51 μg/g (interquartile range, 0.18–8.50), respectively. For calprotectin, a cutoff value of 140 mg/kg predicted endoscopic inflammation with 86% sensitivity, 72% specificity, 64% positive predictive value, 90% negative predictive value, and an area under the curve of 0.87. For hemoglobin, a cutoff value of 1.51 μg/g indicated endoscopic inflammation with 74% sensitivity, 84% specificity, 72% positive predictive value, 84% negative predictive value, and an area under the curve of 0.81. Combining both tests did not increase the predictive accuracy substantially compared with calprotectin or hemoglobin alone (area under the curve, 0.88).
Fecal hemoglobin can identify patients with IBD with active inflammation with a predictive accuracy similar to calprotectin.