Potential of Fecal Calprotectin as an Objective Marker to Discriminate Hospitalized Patients with Acute Severe Colitis from Outpatients with Less Severe Disease

BackgroundAcute severe colitis (ASC) is conventionally diagnosed by Truelove and Witts' criteria which are non-specific and can be affected by other pathologic conditions. Fecal calprotectin (FCP) is a gut-specific marker of inflammation which can predict short-term outcomes in patients with ASC. We aimed to define the role of FCP in the diagnosis of ASC. MethodsThis prospective observational cohort study included adult patients (>18years) with ulcerative colitis (UC) for whom FCP was measured and was under follow-up from April 2015 to December 2016. Patients were divided into two cohorts: (1) all consecutive hospitalized patients with ASC as defined by Truelove and Witts' criteria; (2) outpatients with active UC (defined by Mayo score) who did not fulfill Truelove and Witts' criteria. FCP levels were compared between the two cohorts, and a cutoff for FCP to diagnose ASC was determined.ResultsOf 97 patients, 49 were diagnosed with ASC (mean age: 36.111.9years, 36 males) and 48 with active UC (mean age: 37.9 +/- 12.4years, 25 males). Median FCP levels were significantly higher in patients with ASC [1776(952-3123) vs 282(43-568) mu g/g, p<0.001] than mild to moderately active UC (n=48) or moderately active UC [n=35, 1776(952-3123) vs 332(106-700) mu g/g, p<0.001]. A FCP cutoff of 782g/g of stool had excellent diagnostic accuracy, with an area under the curve of 0.92(95% CI 0.87-0.97), sensitivity of 84% and specificity of 88% to differentiate ASC from active UC.Conclusion FCP could differentiate ASC from mild to moderate patients with UC, but requires validation before clinical use.