P349. Serum calprotectin: a novel biomarker to predict outcome in acute severe ulcerative colitis?
N.C. Hare1,2, N.A. Kennedy2,3, R. Kalla2,3, K. Kingstone4, I.D.R. Arnott2, A.G. Shand2, K. Palmer2, I. Penman5, C.W. Lees2,3, J. Satsangi2,3, 1Taunton and Somerset NHS Foundation Trust, Department of Gastroenterology, Taunton, United Kingdom, 2Western General Hospital, Gastrointestinal Unit, Edinburgh, United Kingdom, 3University of Edinburgh, Gastrointestinal Unit, Centre for Genomic and Experimental Medicine, Edinburgh, United Kingdom, 4Western General Hospital, Department of Clinical Biochemistry, Edinburgh, United Kingdom, 5Royal Infirmary of Edinburgh, Endoscopy Unit, Centre for Liver and Digestive Disorders, Edinburgh, United Kingdom
Acute severe ulcerative colitis (ASUC) remains an important clinical problem, and is associated with significant morbidity and requirement for colectomy. Faecal calprotectin and C-reactive protein (CRP) have previously been shown to predict the need for colectomy, but there is an unmet need for further biomarkers. Serum calprotectin has not previously been analysed for this purpose and may provide a novel way of determining disease activity. The aim of this study was to assess how serum calprotectin relates to faecal calprotectin and other blood markers of inflammation, and to determine whether serum calprotectin on admission predicts colectomy.
Blood samples were collected prospectively from patients who presented with ASUC as defined by the Truelove and Witts criteria. Blood samples were taken within the first 24 hours of admission. Faecal samples were pre-processed using PhiCal™ extraction buffer. Samples were stored at −80°C and then analysed in duplicate using the PhiCal™ calprotectin ELISA according to manufacturer's instructions. Samples with a calprotectin result of >2500 ng/ml were diluted and retested. Statistical comparisons were made between serum calprotectin and other markers of inflammation using Spearman's correlation coefficient, and ROC curve analysis was performed to determine how well each test performed in predicting colectomy.
There were 45 patients recruited to the study with ASUC, of which 22 (49%) were female. Median age on admission was 40 years (interquartile range [IQR] 26–62). Median disease duration was 12 years (IQR 0–59). 26 of the 45 patients had a paired faecal sample for calprotectin analysis. There was no difference in sex, age or disease extent between those with or without faecal calprotectin.
Serum calprotectin correlated significantly with CRP (R2 = 0.46, p < 0.0001) and with albumin (R2 = 0.12, p = 0.023) but not with faecal calprotectin (R2 = 0.02, p = 0.450).
ROC analysis gave an AUC of 0.69 for serum calprotectin, compared with 0.71 for CRP and 0.58 for faecal calprotectin. A cut off for serum calprotectin of 400 ng/ml gave a sensitivity of 0.68 and a specificity of 0.69.
In the setting of acute severe ulcerative colitis, serum calprotectin is comparable with serum CRP in predicting outcome. Further work is needed to establish if it may be a useful predictor of outcome in patients with ulcerative colitis who fail to mount a high CRP response despite endoscopic assessment confirming severe active inflammation. Work is also ongoing to establish its utility in the outpatient setting both in Crohn's disease and ulcerative colitis.