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P219. Faecal calprotectin is an accurate predictor of endoscopic and histological disease activity in IBD

G. Chung-Faye, A. Rahman, K. Sandhu, B. Hayee, J. Tumova, R. Sherwood, King's College Hospital NHS Foundation Trust, Gastroenterology, London, United Kingdom

Background

Assessment of disease activity in inflammatory bowel disease (IBD) is challenging as the gold standards of endoscopy and histology are invasive, expensive and impractical for regular use. Faecal calprotectin (FC) is increasingly being used as a marker of intestinal inflammation in IBD. However, evidence of its role in predicting endoscopic and histological changes in IBD is limited. We explore the role of FC to assess histological disease in IBD, in comparison to C-reactive protein (CRP).

Methods

Retrospective analyses of 209 IBD cases who had a colonoscopy with FC (µg/g) and CRP (mg/L) measurements. The most severe histological inflammation found was graded according to the simplified histology score (0, normal; 1, mild; 2, moderate; 3, severe). The Kruskal–Wallis test (χ2) was used to look for differences between the groups. Receiver operating characteristic (ROC) curves were used to differentiate patients with normal/mild disease (histology scores 0–1) from patients with moderate/severe disease (histology scores 2–3).

Results

In 100 ulcerative colitis (UC) patients, the median FC values for the histology scores; 0, 1, 2, 3 were; 29, 322, 520 and 2497, respectively (graph). The corresponding values for CRP were; 2.5, 5.0, 12.6 and 13.0. Both FC and CRP showed highly significant differences between the different histology groups (FC χ2 = 17.2, p = 0.0007; CRP χ2 = 16.3, p = 0.001). With a cut off value of 244, FC had a 74% sensitivity and 52% specificity for predicting moderate/severe histological disease. The corresponding values for CRP >6 were 70% and 67%.

In 109 Crohn's disease (CD) patients, the median FC for the histology scores; 0, 1, 2, 3 were; 85, 175, 644 and 4144, respectively (graph). The corresponding medians for CRP were; 8, 10, 14 and 100. There were highly significant FC differences between the different histology groups (χ2 = 62.5, p < 0.0001), while CRP just reached significance (χ2 = 9.5, p = 0.02). With a cut-off value of 250, FC had a 90% sensitivity and 82% specificity for predicting moderate/severe disease. The corresponding values for CRP >6 were 72% and 43%.

Graph: Calprotectin vs histology score.

Conclusion

In IBD, FC was strongly predictive of histological disease and with a FC cut off level of ∼250 µg/g gave high levels of sensitivity and moderate specificity for predicting moderate to severe disease. FC showed greater accuracy in CD than in UC and also performed better than CRP. This study highlights the importance of FC as a valuable, non-invasive marker for measuring disease activity in IBD, and may be predictive of disease remission and relapse.