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P118. Neopterin is a novel reliable fecal marker as accurate as calprotectin for predicting endoscopic severity in patients with inflammatory bowel diseases

G. Boschetti1, S. Nancey1, E. Cotte2, A.‑L. Charlois3, D. Moussata1, M. Chauvenet1, K. Stroeymeyt1, D. Kaiserlian4, B. Flourié1

1Lyon-Sud Hospital, Gastroenterology, Pierre-Bénite, France; 2Lyon-Sud Hospital, Digestive Surgery, Pierre-Bénite, France; 3Lyon-Sud Hospital, Statistics, Pierre-Bénite, France; 4Inserm, U 851, Lyon, France

Background: Fecal biomarkers have emerged as an important and non invasive tool for assessing and monitoring disease activity in patients with inflammatory bowel diseases (IBD).

Aim: Prospective comparison of the respective diagnostic accuracy of fecal calprotectin (fCal) and neopterin (fNeo) in predicting endoscopic severity in IBD patients.

Methods: Ninety-four consecutive IBD patients (56 CD, 38 UC) undergoing 109 colonoscopies whatever the indication provided 109 fecal samples for measurement of fCal and fNeo concentrations by ELISA. Endoscopic disease activities were scored independently according to the Simple Endoscopic Score for Crohn's disease (SES-CD) in patients with CD and to the Rachmilewitz index in patients with UC. The respective accuracies of individual and combination of the fecal markers with respect to endoscopic disease severity were assessed by computing correlations, sensitivity, specificity and predictive values at adjusted cutoffs and also tests operating characteristics.

Results: FCal and fNeo concentrations differed significantly in endoscopically active CD (1234±2065 µg/g and 358±238 pmol/g, respectively) in comparison with those in patients without mucosal lesions (209±262 µg/g, and 163±196 pmol/g, both p < 0.001). UC patients with endoscopic lesions had also significantly higher concentrations of fCal (3742±2674 µg/g) and fNeo (468±273 pmol/g) compared with those with endoscopically inactive disease (562±920 µg/g for fCal and 70±83 pmol/g for fNeo, p < 0.001). Both fCal and fNeo concentrations correlated closer with endoscopic scores in UC (r = 0.79 and r = 0.69, respectively; p < 0.001) than in CD (r = 0.57 and r = 0.50, respectively; p < 0.001). Using cutoffs of 250 µg/g for fCal and 190 pmol/g for fNeo previously determined by the ROC curves, the overall accuracy of fCal and fNeo to discriminate between active and inactive mucosal inflammation were in CD 70% and 76%, respectively and in UC 79% and 90%, respectively. In addition, the combination of fCal and fNeo did not improve the performance of fCal or fNeo alone to discriminate quiescent from endoscopically active IBD.

Conclusions: Fecal neopterin is a novel reliable non invasive biomarker with the potential to identify patients with active mucosal inflammation in IBD. The overall accuracy of fNeo as a marker capable of discriminating between the presence and not of endoscopic lesions was similar to that of fCal. Using these fecal markers to monitor patients with IBD could reduce the need for endoscopic examination.