Introduction There is an unmet need for novel blood based biomarkers that offer timely and accurate diagnostic testing in IBD. Faecal calprotectin (FC) is an established biomarker for the diagnosis and management of Inflammatory Bowel Diseases (IBD). However, patient reluctance in sample collection and lab processing delays can impact on the practical utility of this test. We have previously shown that Day 1 SC can predict colectomy outcomes in a cohort of patients with acute severe ulcerative colitis (UC).¹We now aimed to investigate the clinical utility of SC in predicting a diagnosis of IBD.

Method Serum samples were collected prospectively from patients who presented with IBD at their first clinic visit and stored at –80°C. A total of 146 patient serum samples (n = 84 newly diagnosed IBD, n = 62 symptomatic and healthy controls) were included in the study from August 2013 to January 2015. The mean age of the IBD and control cohorts were 34 and 32 years respectively (range 18–73 years) and 60% (n = 87) were male. Paired FC was available within 30 days of SC in 66 patients (IBD n = 43, non-IBD n = 23). Data analysis was performed using R 3.1.2.

Results Serum calprotectin and CRP were able to discriminate IBD from controls with similar areas under the receiver operator characteristics curve (AUROC) of 0.84 (95% confidence interval [CI] 0.78–0.91) and 0.83 (95% CI 0.77–0.90) respectively (p = 0.76 for comparison of ROC curves). Serum calprotectin >725 ng/mL gave a sensitivity of 76% and specificity of 76%. Combining serum calprotectin and CRP using linear discriminant analysis of log-transformed data significantly improved the AUROC to 0.88 (95% CI0.83–0.94; p = 0.01 vs CRP and 0.04 vs serum calprotectin). Pairwise comparison of CRP and serum calprotectin is shown in figure 1. In those with a normal CRP (n = 34 IBD, n = 55 non-IBD), serum alprotectin was able to discriminate IBD from controls with an AUROC of 0.74 (95% CI 0.64–0.85). Paired SC and FC were available for 64 patients. Within that cohort, the AUROC for FC was not significantly higher at 0.92 (95% CI 0.83–1.00) than for serum calprotectin at 0.88 (95% CI 0.80–0.96) (p for comparison 0.53). Serum calprotectin was, however, significantly correlated with faecal calprotectin (Spearman’s rho = 0.51, p < 0.0001).

Conclusion Serum Calprotectin is a promising blood based biomarker and offers timely and practical diagnostic testing in the clinical setting. Our findings require further validation in large multi-centre cohorts.

Disclosure of interest R. Kalla Grant/ Research Support from: IBD Character, Conflict with: Supported by Calpro AS, N. Kennedy Grant/ Research Support from: Wellcome Trust, Conflict with: Abbvie, MSD, Warner Chilcott, Ferring speaker fees, N. Ventham Grant/ Research Support from: IBD BIOM, M. Visconti: None Declared, A. Adams: None Declared, A. Jarvie: None Declared, R. Pattenden: None Declared, J. Satsangi Grant/ Research Support from: EC Grants, Wellcome, CSO, MRC, Consultant for: Takeda, Conflict with: MSD speaker fees.

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Abstract PTH-062 Figure 1

Reference

1. Hare NC et al. P349 Serum calprotectin: a novel biomarker to predict outcome in acute severe ulcerative colitis? J Crohn’s Colitis 2014;8:S210