Triaging colorectal urgent referrals in the COVID-19 era using faecal immunochemical testing: a prospective UK real-world multicentre cohort study.

Objective: During the early COVID-19 pandemic, UK guidelines advocated faecal immunochemical tests (FIT) with a threshold of 10 µg/g to help secondary care clinicians triage urgent suspected colorectal cancer (CRC) referrals. We aimed to evaluate the real-world performance and impact of FIT in a high-risk cohort referred against National Institute for Health and Clinical Excellence NG12 (2015) criteria.

Methods: Multicentre prospective observational cohort study of FIT at all four secondary care hospitals in Devon (UK) between 1 April 2020 and 31 December 2020. FIT use was at the discretion of primary and secondary care clinicians. Incident CRC cases were identified ≥12 months after general practitioner (GP) referral using regional National Bowel Cancer Audit data linkage. We assessed diagnostic accuracy and healthcare utilisation in patients with and without FIT.

Results: Overall, 6698 patients were included: 55% female, median age 72 years (IQR 65-82). Just over half (53%, 3552) of patients underwent FIT with a positivity rate of 34% (n=1237). CRC prevalence in patients with no FIT, positive FIT and negative FIT was 6% (189), 11% (137) and 0.5% (11), respectively. The prevalence of all cancers, including non-CRCs, was similar among FIT and no-FIT cohorts (p=0.74). Sensitivity and specificity of FIT for CRC were 0.93 (95% CI 0.87 to 0.96) and 0.68 (95% CI 0.66 to 0.69), respectively. Patients with negative FIT underwent fewer lower gastrointestinal endoscopies (no FIT 62% (1964) vs positive FIT 69% (857) vs negative FIT 36% (835)), p=0.0005).

Conclusions: FIT is a useful triage tool for patients with suspected CRC which safely reduces endoscopy demand and prioritises those at greatest cancer risk. Standardised regional referral pathways, greater use of 'straight-to-test' investigations and GP support are needed to maximise its impact.