BACKGROUND: Mucosal healing in ulcerative colitis leads to a decreased need for medication and decreased risk of disease relapse and colectomy. Histological healing seems to improve the disease prognosis even further. An assessment of both endoscopic and histological mucosal healing requires endoscopy, and the need for a reliable noninvasive biomarker to predict disease relapse is obvious.

METHODS: Seventy patients were included and followed up for 12 months. Inclusion criteria were a total Mayo score ≤1 and a Mayo endoscopic score = 0. The patients underwent sigmoidoscopy with rectal biopsies. Fecal calprotectin (FC) was measured 2 to 3 days before the sigmoidoscopy. The tissue samples were evaluated for neutrophilic inflammation. We aimed at testing the predictive performance of FC and histological inflammatory activity on disease relapse.

RESULTS: A baseline FC level of more than 321 mg/kg predicted disease relapse at both the 6- and 12-month follow-ups. Histological inflammatory activity, C-reactive protein, or length of remission was not predictive of relapse. Of note, 11.8% of all patients had histological inflammatory activity despite endoscopic remission and were found to have a higher level of FC (236.5 versus 56 mg/kg, P = 0.02). A receiver operating characteristic analysis estimated a cutoff level of ≤40.5 mg/kg for FC (area under the curve, 0.755 and confidence interval 95%, 0.5895-0.9208) for predicting a histological inflammatory activity score of 0.

CONCLUSIONS: FC measurements can be used to identify patients with increased risk of relapse after 6 and 12 months and to predict histological mucosal healing. Regular measurement of FC may alter disease monitoring and improve prognosis, and may decrease the need for endoscopy.