Low Fecal Calprotectin Predicts Histological Healing in Patients with Ulcerative Colitis with Endoscopic Remission and Leads to Prolonged Clinical Remission

Background Consensus regarding the cutoff value of fecal calprotectin (FC) for predicting histological healing (HH) in ulcerative colitis (UC) is lacking. This study aimed to determine an optimal FC cutoff value for predicting HH in patients with UC with clinical and endoscopic remission. Furthermore, FC's predictability for prolonged clinical remission (CR) was investigated. Methods Patients with UC in clinical and endoscopic remission, defined as a partial Mayo score (PMS) <= 2 points and a Mayo endoscopic subscore 0-1, were prospectively enrolled. Biopsy samples were evaluated by Geboes score (GS), with HH defined as a GS < 2.0. Patients were followed for 2 years or until relapse, defined as a PMS > 2 or medication escalation. Results Seventy-six patients with UC were included. The median FC value in patients with HH (n = 40) was 56.2 mu g/g, significantly lower than that in those with histological activity (118.1 mu g/g; P < .01). The area under the curve (AUC) in a receiver operating characteristic (ROC) curve analysis to predict HH for FC was 0.71 (95% confidence interval [CI], 0.59-0.83), with an optimal cutoff value of 82.7 mu g/g (73% sensitivity; 64% specificity; P < .01). Of 74 patients observed for 2 years, 54 (73%) had prolonged CR. In the ROC curve analysis, the AUC to predict prolonged CR for FC was 0.79 (95% CI, 0.68-0.90), equivalent to that for HH (0.73; 95% CI, 0.64-0.86; P = .40). The optimal FC cutoff value to predict prolonged CR was 84.6 mu g/g (72% sensitivity; 85% specificity; P < .01). Conclusions Fecal calprotectin < 82 mu g/g predicts HH in patients with UC with clinical and endoscopic remission. Low FC leads to prolonged CR, equivalent to HH. Lay Summary Fecal calprotectin (FC) levels < 82 mu g/g predict histological healing in ulcerative colitis patients with clinical and endoscopic remission. Low FC leads to prolonged clinical remission for up to 2 years in those with clinical and endoscopic remission, equivalent to histological healing.