Stratifying Crohn's Using Biomarker Assessment

Crohn's disease (CD) is a relapsing-remitting condition that requires lifelong monitoring. Non-invasive tests such as faecal calprotectin (FC) are more acceptable to patients and cost-effective than invasive tests such as colonoscopy. FC levels can also accurately predict the degree of healing seen within the bowel at colonoscopy. FC testing is labour intensive, and results are often indeterminate. There is interest in a newer test called quantitative Faecal Immunochemical Testing (qFIT) in patients with CD. qFIT measures the amount of blood within the stool and is used in the Scottish Bowel Cancer Screening Programme. qFIT is an easier and more acceptable test for patients and is less labour intensive and cheaper for the lab to process than FC. qFIT is a useful test to 'rule-out' significant colorectal pathology including bowel cancer, high risk polyps and inflammatory bowel disease in patients in the primary care setting. It has also been used to predict the degree of healing seen within the bowel at colonoscopy and to predict the risk of relapse in patients with UC, but not in CD. There are no studies in the UK to date comparing FIT to FC as a monitoring test in patients with well-controlled CD. Unpublished audit data from our group has suggested that low serum zinc has higher predictive accuracy at determining risk of future flare than both FC and CRP; we are unsure if this is due to higher faecal losses in 'grumbling' CD patients. This study could identify a cheaper, more acceptable and easier to interpret test to guide disease activity monitoring, flare risk and treatment decisions in quiescent CD.