P053 Comparison of accuracy between fecal immunochemical test and fecal calprotectin for predicting mucosal healing in quiescent ulcerative colitis patients

Abstract

BACKGROUND: Non-invasive stool tests including fecal immunochemical test (FIT) and fecal calprotectin (FC) are known to be a reliable biomarker for mucosal healing (MH) in ulcerative colitis (UC). However, direct comparison of these fecal tests for predicting MH in inactive UC patients has yet to be evaluated. We aimed to compare the accuracy of FIT and FC for predicting MH in UC patients in clinical remission. METHODS: This was a prospective, multicenter study conducted in 3 tertiary hospitals between February 2016 and January 2018. UC patients in clinical remission for at least 3 months or more underwent colonoscopy and MH was evaluated using Mayo endoscopic subscore (MES). Fecal samples were collected for FIT and FC 24 hours before colonoscopy. Receiver operating characteristic (ROC) curve and cut-off value of the best accuracy for predicting MH was assessed in each test. Independent predictive factors for MH were identified by logistic regression analysis. RESULTS: Among 127 patients (male 86, median age of diagnosis 44 [range 14–77]) of UC in clinical remission, only 65 (51.2%) showed complete MH (MES = 0). Area under curve (AUC) of FC was significantly higher than FIT (AUC 0.858 vs 0.707, P < 0.001) whereas this difference disappeared when MH was defined as MES 0 or 1 (AUC 0.820 vs 0.813, P = 0.891). When cut-off value was set as 70 μg/g for FC and 10 mg/mL for FIT, sensitivity, specificity, positive predictive value and negative predictive value were 89.2, 71, 76.3, and 86.3 and 92.3, 50, 65.9, and 86.1, respectively. Multivariate logistic regression analysis showed that age of diagnosis >45, hematocrit >44, FC <70 μg/g, and FIT <10 mg/mL were identified as independent predictive factors for MH (MES = 0). CONCLUSION(S): Our study demonstrated that FC is more sensitive than FIT for predicting complete MH in quiescent UC patients. The best cut-off value of FC and FIT for MH in these patients is found as 70 μg/g and 10 mg/mL, respectively. Age of diagnosis and hematocrit are additional predictors for MH.