Clinical impact of double-faecal immunochemical testing following implementation into standard triage and investigation of primary care referrals in patients with lower gastrointestinal symptoms.

Abstract

Background: Faecal immunochemical testing has rapidly been established as the first-line triage for patients with symptoms suspicious for colorectal cancer. However, the reported low compliance of test returns issued from primary care is concerning. This article reports the real-world impact of implementation of a double-faecal immunochemical testing pathway for symptomatic referrals into routine clinical practice.

Methods: All eligible referrals between November 2021 and October 2022 were sent two faecal immunochemical tests via the faecal immunochemical testing interface office. Colorectal investigations were instigated if either test result was ≥10 µg haemoglobin per g. Referrals with double-negative results were reviewed by consultants who decided whether symptoms merited further investigation. Cancer registry follow-up data were cross-checked, and a further electronic registry allowed capture of re-referrals.

Results: Some 5425 patients were triaged using double-faecal immunochemical testing, with 5116 (94.3%) completing at least 1 and 4607 (84.9%) both faecal immunochemical tests. The positivity of one test was 20.8%, rising to 27.8% where both tests were completed. The number of referred patients undergoing colorectal investigation fell from 90% before faecal immunochemical testing-directed pathways to 56.6% owing to a reduction in investigating patients with double-negative results. The double-faecal immunochemical testing pathway had a sensitivity of 94.3% for the detection of colorectal cancer, with 37.5% of cancers with a negative first test being detected by the second. Only 3.3% of patients triaged through the double-faecal immunochemical testing pathway were re-referred.

Conclusion: The double-faecal immunochemical testing pathway demonstrated high test return rates, a reduction in unnecessary investigations, and colorectal cancer detection rates similar to preimplementation rates.