Faecal Haemoglobin Concentration As a Predictor of Colorectal Neoplasia in Patients at Moderate to High Risk of Colorectal Cancer Attending for Surveillance Colonoscopy

Background: Quantitative faecal immunochemical tests (FIT) measure faecal haemoglobin concentration (f-Hb), which increases in the presence of colorectal neoplasia and is related to the severity of disease. We examined the diagnostic accuracy of FIT in patients at moderate to high risk of colorectal cancer (CRC) attending for surveillance colonoscopy as per national guidelines. Methods: We undertook a prospective study in two University hospitals, one in Scotland and one in England. Between June 2014 and September 2016, 1103 consecutive patients were invited to complete a FIT before their scheduled colonoscopy: f-Hb was analysed on an OC-Sensor io automated analyser (Eiken Chemical Co., Ltd, Tokyo, Japan)) with a limit of detection (LoD) of 2 µg Hb/g faeces. The diagnostic accuracy of f-Hb for CRC and higher-risk adenoma (HRA) was examined. Findings: 643 patients returned a FIT. Four patients with known IBD were excluded, leaving 639 (57·9%) in the study: age range: 25-90 years (median: 64 years, IQR: 55-71): 54·6% male. Of 593 patients who returned a FIT and completed colonoscopy, 41 (6·9%) had advanced neoplasia (4 CRC, 37 HRA): 238/593 patients (40·1%) had detectable f-Hb of whom 31 (13·0%) had advanced neoplasia (2 CRC, 29 HRA) compared to 10 (2·8%) in those with undetectable f-Hb (2 CRC, 8 HRA).Detectable f-Hb gave negative predictive values of 99·4% for CRC and 97·2% for CRC plus HRA. Interpretation: In patients at moderate to high risk of CRC who are under colonoscopy surveillance, a FIT at the LoD can provide an objective estimate of the risk of advanced neoplasia and could enable tailored scheduling of colonoscopy. Funding Statement: Chief Scientist Office; grant reference number CZH/4/1032. Declaration of Interests: CGF has undertaken consultancy with Kyowa-Medex Co., Ltd, Tokyo, Japan, and has received travel support from Alpha Labs Ltd, Eastleigh, UK. Other authors - none. Ethics Approval Statement: This study had ethical approval from NRES North of Scotland Ethics Committee: reference: 14/NS/0059.