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P314. Accuracy of fecal calprotectin in the assessment of post-operative endoscopic recurrence in patients with Crohn's disease

G. Boschetti1, D. Moussata1, A.-L. Charlois2, B. Flourié1, S. Nancey1, 1Lyon-Sud Hospital, Gastroenterology, Pierre-Bénite, France, 2Lyon-Sud Hospital, Statistics, Pierre-Bénite, France

Background

Endoscopic post-operative recurrence is frequent in Crohn's disease (CD) and is highly predictive of further clinical recurrence. Aims: i) to assess the performance of fecal calprotectin (fCal) to discriminate in CD patients who had undergone an ileo-colonic resection those who experienced an endoscopic recurrence from those who did not; ii) to determine the best threshold of fCal capable to distinguish CD patients with or without a post-operative endoscopic recurrence.

Methods

At least one ileo-colonoscopy was performed in 28 consecutive patients with CD who had undergone a curative ileocolonic resection (2 colonoscopies were performed in 5 of them) during the previous year. Post-operative endoscopic recurrence was defined as a Rutgeerts endoscopic severity index ≥i2. Before the colon cleansing, a fecal sample was collected for routine fCal measurement by ELISA (Bühlmann, Swiss). Concentrations of fCal were compared in patients who experienced an endoscopic recurrence or not using the Mann–Whitney test. The accuracy of fCal to discriminate between patients in endoscopic remission (i0, i1) from those in endoscopic recurrence (i2, i3, i4) was determined by a ROC curve and sensitivities, specificities, positive (PPV) and negative predictive values (NPV) were calculated using various fCal levels as cut-off points.

Results

Among the 33 ileo-colonoscopies performed, a postoperative endoscopic recurrence was assessed in 10 patients (all in clinical remission). FCal concentrations were significantly higher in patients with an endoscopic recurrence compared with those without (368±333 µg/g vs 106±79 µg/g; p < 0.001). The AUC of fCal to discriminate between patients with or without a post-operative endoscopic recurrence was 83%. The respective accuracies of fCal according to fCal threshold are summarized in Table 1.

Table 1
Cut-off (µg/g)Accuracy (%)
 SensitivitySpecificityPPVNPV
fCal = 10089506092
fCal = 15066876687
fCal = 20055876284
fCal = 25033875078

Conclusion

FCal using a cut-off of 100 µg/g had the best sensitivity and NPV to distinguish CD patients in clinical remission who experienced a post-operative recurrence from those who did not. If these results are confirmed in a larger study, finding a fCal concentration above this cut-off might allow to avoid performing some ileo-colonoscopies in the CD post-operative setting.