Faecal immunochemical tests for occult blood testing should not be used outside of bowel screening: An audit of a large general practice

Abstract

INTRODUCTION: The faecal immunochemical test (FIT) detects small quantities of human haemoglobin in faeces. This test has increasingly become the screening tool of choice in bowel cancer screening programmes worldwide, including New Zealand's upcoming national screening programme. AIM: This study audited the appropriate use of faecal immunochemical tests (FIT) in general practice as current recommendations discourage the use of FIT outside the National Bowel Screening Programme. METHODS: Data on all FIT requested by a multiclinic general practice serving 16 000 patients from May 2017 to May 2018 were extracted from clinical records. Patient characteristics, results of tests, clinical rationale for the test, number of referrals and results and the completeness of clinical evaluation were recorded. RESULTS: In all, 184 patients received an FIT, with 13 (7.1%) positive and 145 (78.8%) negative tests, and 26 (14.1%) tests declined by the laboratory. Nine patients (69.2%) with a positive FIT, 12 patients (8.1%) with a negative FIT and one patient (3.8%) with a declined test were referred to gastroenterology services. Seven colorectal cancers were detected, all in patients with a positive FIT who were aged between 67 and 91 years. FIT was requested most for changes in bowel habit (53%) and blood in stool (15%); 10% of tests were ordered for reassurance and 9% did not record an indication for the test. Two general practitioners (of 17 in the practice) accounted for over half of all tests requested. CONCLUSIONS: Because FIT is only a screening tool for colorectal cancer, direct referral is recommended for symptomatic patients. Although cancers were detected only in patients with positive FITs, these patients would have qualified for direct referral for definitive investigation, and a referral was made concurrently. Awaiting test results may also delay necessary referrals and a negative FIT may produce false reassurance.