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P261. Determination of faecal haemoglobin is equally effective as faecal calprotectin in identifying inflammatory bowel disease patients with active endoscopic inflammation

E. Mooiweer1, H.H. Fidder1, K.J. van Erpecum1, P.D. Siersema1, R.J. Laheij1, B. Oldenburg1, 1University Medical Centre Utrecht, Department of Gastroenterology and Hepatology, Utrecht, Netherlands

Background

Faecal calprotectin is a non-invasive tool to asses colonic inflammation in patients with inflammatory bowel disease (IBD). However, the diagnostic accuracy of calprotectin is modest and analysis is relatively costly and therefore additional markers are needed. We compared the efficacy of faecal haemoglobin and calprotectin in the prediction of active endoscopic inflammation in IBD patients.

Methods

Consecutive patients with either Crohn's colitis (CD) or ulcerative colitis (UC) scheduled for surveillance colonoscopy collected a stool sample prior to the start of bowel preparation. Three experienced endoscopists assessed the presence of active inflammation in each colonic segment. Stool samples were analyzed for calprotectin and haemoglobin, both with a Ridascreen® enzyme-linked immunosorbent assay (R-Biopharm, Germany) and were analyzed without reference to colonoscopy findings and vice versa. ROC statistics were used to determine cutoff values for calprotectin and haemoglobin.

Results

A total of 119 patients were included, of which 54 patients had CD, 59 had UC and 6 indeterminate colitis. Median (interquartile range [IQR]) calprotectin and haemoglobin concentrations were 118 µg/g (IQR 31–367) and 0.48 µg/g (IQR 0.27–5.73) respectively. Active inflammation was encountered in 43 patients (36%) (5 severe, 9 moderate and 29 mild). Calprotectin and haemoglobin levels were significantly higher in patients with active inflammation compared to patients with no inflammation [451 µg/g vs 52 µg/g, p < 0.01 and 10.34 µg/g vs 0.34 µg/g, p < 0.01 respectively (Mann–Whitney U test)]. A cutoff value of 172 µg/g for calprotectin predicted endoscopic inflammation with 79% sensitivity, 80% specificity, 69% positive predictive value and 87% negative predictive value. The predictive accuracy of calprotectin (area under the curve [AUC]) was 0.88 which was similar for patients with CD and UC (AUC 0.86 and 0.86 respectively). For haemoglobin, a cutoff value of 1.45 µg/g indicated endoscopic inflammation with 77% sensitivity, 88% specificity, 79% positive predictive value and 87% negative predictive value. The predictive accuracy of haemoglobin was 0.88 (AUC) which was similar for patients with CD and UC (AUC 0.87 and 0.81 respectively). A combination of both tests did not increase the predictive accuracy compared to each test alone (AUC 0.88).

Conclusion

Faecal haemoglobin can identify IBD patients with active inflammation with a predictive accuracy similar to faecal calprotectin.