Faecal Immunochemical Test (FIT) Value-Based Algorithm to Triage Symptomatic Colorectal Patients: A Retrospective Study From a Tertiary Care Hospital

Background The aim was to evaluate the diagnostic accuracy of quantitative faecal immunochemical testing (FIT) in diagnosing colorectal cancer in symptomatic patients and using it to prioritize patients for urgent colorectal investigations. Methods A retrospective review was done of all symptomatic, FIT-positive patients referred from primary care to the colorectal clinic as per the National Institute for Health and Care Excellence (NICE) DG30 pathway from November 1, 2021, to February 11, 2022. Patients under 18 years of age were excluded. All patients were triaged to test (TTT) or booked in face-to-face (F2F) clinics according to a local algorithm. The data was collected in Microsoft Excel (Microsoft Corporation, Redmond, Washington, United States), and statistical analysis was performed using IBM SPSS Statistics for Windows (IBM Corp., Armonk, New York, United States). Results Out of 915 FIT-positive patients, 774 (84.5%) patients were TTT and 70 (7.65%) were booked in F2F clinics. The mean age was 71 years, and the majority were females (n=488 (F:M = 53:47)). However, a higher prevalence of positive FIT test was observed in men than in women at higher cut-off values of >100 and >200 μg Hb/g faeces (18.79 % vs 17.48% and 12.78% vs 11.69%, respectively). The number needed to scope was 10.8, 6.03, and 5.20 at cut-off values of ≥10, >100, and >200 μg Hb/g, respectively. At cut-off values of ≥10, >100, and >200 μg Hb/g, the specificity for colorectal cancer (CRC) with a 95% confidence interval (95% CI) was 63.75 %, 88.10%, and 92.27 %, respectively, and the positive predictive value (PPV) was 9.63, 18.20, and 21.24, respectively. The majority of the patients (30.9%) had no pathology on colonoscopy, whereas CRC was detected in 9.8%. Conclusion Quantitative FIT in symptomatic colorectal patients can be used to triage patients to investigations more appropriately, reducing the burden on outpatient and endoscopy units and improving the overall efficacy of health provision.