Low Fecal Calprotectin Predicts Sustained Clinical Remission in Inflammatory Bowel Disease Patients: A Plea for Deep Remission

Background and aims: Mucosal healing has become the treatment goal in patients with ulcerative colitis (UC) and Crohn's disease (CD). Whether low fecal calprotectin levels and histological healing combined with mucosal healing is associated with a further reduced risk of relapses is unknown. Methods: Patients with CD, UC or inflammatory bowel disease-unclassified (IBD-U) scheduled for surveillance colonoscopy collected a stool sample prior to bowel cleansing. Only patients with mucosal healing (MAYO endoscopic score of 0) were included. Fecal calprotectin was measured using a quantitative enzyme-linked immunosorbent assay (R-Biopharm, Germany). Biopsies were obtained from four colonic segments, and histological disease severity was assessed using the Geboes scoring system. Patients were followed until the last outpatient clinic visit or the development of a relapse, which was defined as IBD-related hospitalization, surgery or step-up in IBD medication. Results: Of the 164 patients undergoing surveillance colonoscopy, 92 patients were excluded due to active inflammation or missing biopsies. Of the remaining 72 patients (20 CD, 52 UC or IBD-U), six patients (8%) relapsed after a median follow-up of 11 months (range 5-15 months). Median fecal calprotectin levels at baseline were significantly higher for patients who relapsed compared with patients who maintained remission (284 mg/kg vs. 37 mg/kg. p < 0.01). Fecal calprotectin below 56 mg/kg was found to optimally predict absence of relapse during follow-up with 64% sensitivity, 100% specificity, 100% negative predictive value and 20% positive predictive value. The presence or absence of active inflammation determined by Geboes cut-off score of 3.1 was less strongly associated with the risk of relapse (64% sensitivity, 33% specificity, 9% negative predictive value and 92% positive predictive value. Conclusion: Low calprotectin levels identify IBD patients who remain in stable remission during follow-up.