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P237 Accuracy of a rapid fecal calprotectin test as a predictor of mucosal healing in patients with Ulcerative Colitis (UC)

R. Ferreiro*, M. Barreiro-de Acosta, N. Vallejo, D. De la Iglesia, L. Urisarri, I. Baston, A. Lorenzo, J.E. Dominguez-Munoz

University Hospital Santiago de Compostela, Gastroenterology, Santiago, Spain

Background

Predicting mucosal healing in UC patients by measuring non-invasive biomarkers could be useful to avoid unnecessary colonoscopies. Aims of this study were 1) to evaluate the predictive value of a quantitative rapid fecal calprotectin (FC) test for mucosal healing in UC patients as defined by the Mayo score, and 2) to evaluate the difference in FC between endoscopic Mayo -0 and Mayo-1 score.

Methods

A prospective observational cohort study was carried out. Every adult UC patient referred to our Endoscopy Unit for a colonoscopy were consecutively included. Patients were asked to collect a small sample of feces within the 48 hours prior to bowel cleansing for colonoscopy. Fecal calprotectin was measured using a rapid test (Quantum blue®), which allows obtaining the result in less than 30 minutes. Mucosal healing was defined as an endoscopic Mayo sub-score of 0 or 1. Mayo-0 was defined as normal or inactive disease and Mayo-1 as presence of erythema, decreased vascular pattern or mild friability. A ROC curve analysis was applied to define the optimal FC cut-off value for mucosal healing. The correlation analysis between FC, endoscopic score and clinical activity was based on Spearman's correlation coefficient rank (r).

Results

59 consecutive UC patients were prospectively included (mean age 47 years, range 21 to 74 years, 28 female). Thirty one patients (52.5%) were classified as Mayo 0, 12 (20.3%) as Mayo 1, 6 (10.2%) as Mayo 2 and 10 (16.9%) as Mayo 3. FC levels correlated with the Mayo endoscopic score (r = 0.677; p < 0.001). Median FC levels were 50µg/g for Mayo 0, 111µg/g for Mayo 1, 413µg/g for Mayo 2 and 1406µg/g for Mayo 3. FC as predictor of mucosal healing (Mayo 0 or 1) presented an area under the ROC curve (AUC) of 0.973 (95% IC = 0.893-0.998), and of 0.861 (95% IC=0.765-0.937) to predict endoscopic Mayo score 0. FC showed an ROC AUC of 0.782 (95% CI 0.634-0.930) to differentiate Mayo 0 from Mayo 1. A FC >35µg/g has a sensitivity of 72.2%, specificity of 84%, positive predictive value of 64.8% and negative predictive value of 88.1% to predict endoscopic activity.

Conclusion

FC is a good predictor of endoscopic activity in UC patients. Although patients with a Mayo sub-score of 1 present higher FC levels than those with Mayo sub-score of 0, FC is especially accurate to predict mucosal healing as defined by a Mayo score of 0 or 1.