Accuracy of four fecal assays in the diagnosis of colitis.

PURPOSE: This study was designed to evaluate the accuracy of four different fecal markers in discriminating between irritable bowel syndrome, inflammatory bowel disease, and other forms of colitis and to examine the feasibility of collecting fecal samples in outpatients.

METHODS: We prospectively included 20 patients with irritable bowel syndrome, 36 with inflammatory bowel disease (24 Crohn's disease, 12 ulcerative colitis), and 18 with other forms of colitis (8 infectious colitis, 5 ischemic colitis, 5 medication-induced colitis). Diagnosis was established by clinical, laboratory, and endoscopic workup. Blinded fecal samples were measured for calprotectin (PhiCal-Test, ELISA), lactoferrin (IBD-SCAN, ELISA), Hexagon OBTI (immunochromatographic test for detection of human hemoglobin), and LEUKO-TEST (lactoferrin latex-agglutination test).

RESULTS: Overall accuracy for discriminating irritable bowel syndrome from inflammatory bowel disease or other forms of colitis was recorded, respectively: IBD-SCAN 91/100 percent, PhiCal-Test 89/100 percent, LEUKO-TEST 83/89 percent, Hexagon OBTI 77/84 percent, C-reactive protein 71/79 percent, and blood leukocytes 63/68 percent. Differentiation of inflammatory bowel disease from other forms of colitis with fecal markers was as follows: range of overall accuracy from 43 to 50 percent. Overall accuracy (in percent) for discrimination of irritable bowel syndrome from patients with Crohn's disease in remission (CDAI<150) was: IBD-SCAN 90, PhiCal-Test 90, LEUKO-TEST 85, Hexagon OBTI 77. Calprotectin and lactoferrin were significantly elevated in patients with Crohn's disease with CDAI>150 compared with those in remission. Fecal sampling feasibility in outpatients was high (acceptance rate 95 percent).

CONCLUSIONS: IBD-SCAN and PhiCal-Test have the best overall accuracy for detection of colitis, followed by LEUKO-TEST, Hexagon OBTI, C-reactive protein, and blood leukocytes. Accuracy of fecal markers is high even in patients with Crohn's disease in remission. Fecal sampling feasibility was high in outpatients. Because fecal markers are unspecific, endoscopic workup remains crucial to determine the underlying cause of colitis.