Use of a faecal immunochemical test for haemoglobin can aid in the investigation of patients with lower abdominal symptoms

Abstract

AbstractThis study aimed to determine whether patients with lower abdominal symptoms can be investigated quickly using results of faecal haemoglobin concentration (f-Hb) measurements, and whether this test could form part of a diagnostic pathway for significant colorectal disease.Nine hundred and nine consecutive patients referred from primary care for colonoscopy were invited: 507 submitted samples for f-Hb measurement with a quantitative faecal immunochemical test for haemoglobin (FIT) (HM-JACKarc, Kyowa-Medex, Japan) and a diagnostic colonoscopy was completed in 484 patients.Colorectal cancer (CRC), higher risk adenoma (HRA), inflammatory bowel disease (IBD) and/or colitis was found in 45 patients (9.3%); these had significantly higher (p<0.0001) f-Hb than the group of 243 with normal colonoscopy plus the 196 patients with less significant clinical findings. The 11 (2.2%) patients with CRC all had f-Hb >190 μg Hb/g faeces. Using a f-Hb cut-off of 10 μg Hb/g faeces, for the group with CRC or HRA or IBD or colitis, sensitivity was 68.9%, specificity 80.2%, positive predictive value (PPV) 26.3% and negative predictive value (NPV) 96.2%. Sensitivity and NPV were 100% for CRC suggesting f-Hb is a good rule-in test for CRC. Of the 243 patients with normal colonoscopy, 81.2% had f-Hb<10 μg Hb/g faeces.The high NPV for significant colorectal diseases suggests that f-Hb could be used as a rule-out test in this context. Potential exists for using f-Hb measurements to investigate symptomatic patients and guide the use of colonoscopy resources: detailed algorithms for the introduction of f-Hb measurements requires further exploration.