Incorporating faecal haemoglobin measurement using the faecal immunochemical test (FIT) in the referral, triage and prioritisation pathway for patients with colorectal symptoms

Incorporating faecal haemoglobin (FHb) measurement using the faecal immunochemical test (FIT) in the investigation pathway for patients with colorectal symptoms may improve access to colonoscopy for those at greatest risk of significant disease. To derive a colorectal symptom pathway incorporating standard clinical and FIT data to guide referral, triage, and prioritisation of cases in New Zealand. Diagnostic accuracy of FIT to rule out colorectal cancer (CRC) was determined by meta-analysis. Thereafter, the risk of CRC after FIT was estimated for common clinical presentations by Bayesian methodology, using a specifically collated retrospective cohort of symptomatic cases. A symptom/FIT pathway was developed iteratively following multi-disciplinary engagement. Eighteen studies were included in meta-analysis. The sensitivity and specificity for CRC were 89.0% (95%CI 87.0-90.9%) and 80.1% (95%CI 77.7-82.4%) respectively, at a FHb threshold of >10mcg haemoglobin per gram stool, and 95.7% (95%CI 93.2-97.7%) and 60.5% (95%CI 53.8-67.0%) respectively, at the limit of detection. The final pathway was 97% sensitive for CRC, compared with 90% for the current direct access criteria, and requires 47% fewer colonoscopies. Estimated prevalence of CRC among those declined investigation was 0.23%. Incorporating FIT in the new patient symptomatic pathway as presented appears feasible, safe, and allows for resources to be targeted to those at greatest risk of disease. Further work is needed to ensure equity for Māori if this pathway were introduced nationally.