Objectives: Fecal calprotectin (fCal) is widely used as marker of gut inflammation and is strongly associated with the severity of endoscopic lesions in Crohn's disease (CD). We analyzed the relationships between levels of fCal and high-sensitivity C-reactive protein (hsCRP) and the presence and severity of postoperative endoscopic recurrence in asymptomatic CD patients (Harvey-Bradshaw index≤3).
Methods: Blood and fecal samples were collected in consecutive asymptomatic CD patients (Harvey-Bradshaw index 0.85 ± 0.19, mean ± s.e.m.) who had undergone an ileocolonic resection. hsCRP and fCal were measured and a routine ileocolonoscopy was performed within 18 months (median 7 months) from resection, to detect endoscopic recurrence according to the Rutgeerts score.
Results: Eighty-six patients were included in this prospective multicenter observational cohort. fCal concentrations differed significantly in patients with endoscopic recurrence when compared with those in endoscopic remission (mean ± s.e.m.: 473 ± 78 μg/g vs. 115 ± 18 μg/g; P<0.0001). The area under the receiver operating characteristic (ROC) curve to discriminate between patients in endoscopic remission and recurrence was 0.86 for fCal and lower for hsCRP (0.70). The best cutoff point for fCal to distinguish between endoscopic remission and recurrence was 100 μg/g as determined by the ROC curve, and its sensitivity, specificity, positive and negative predictive values (NPVs), as well as overall accuracy were 95%, 54%, 69%, 93%, and 77%, respectively.
Conclusion: Measurement of fCal concentrations is a promising and useful tool for monitoring asymptomatic CD patients after ileocolonic resection. Taking into account the high NPV of fCal, a threshold below 100 μg/g could avoid systematic ileocolonoscopies in 30% of patients from this population.