Variations in the Use of Faecal Immunochemical Testing (FIT) in Primary Care in England: A Population-Based Cohort of 531,735 FITs from 495,121 Patients Between 2019 and 2023.

Background/objectives: Faecal Immunochemical Testing (FIT) is recommended for patients presenting to primary care with symptoms suggestive of colorectal cancer. This study quantified variations in use across England.

Methods: Retrospective cohort of English patients (≥18 years) with a FIT result reported in routinely collected primary care records, 2019-2023. Rates of FIT testing by age, sex, year and region were adjusted using Poisson regression. Multivariate logistic regression compared the effect of factors on the proportion of results exceeding the recommended referral threshold (10µgHb/g).

Results: Between 01/01/2019 and 05/06/2023 there were 531,735 FIT results among 495,121 patients. Rates of testing increased from 0.69 per thousand person-years in 2019 (95% CI 0.68-0.71) to 27.70 in 2023 (95% CI 27.56-27.85). There were large variations in testing between regions, with rates >3-fold higher in the Northeast than the West Midlands: 17.05 (95% CI 16.87-17.23) versus 4.72 (95% CI 4.67-4.76) per thousand person-years. About 20.4% of FIT results were ≥10µgHb/g. Despite increased testing, this did not change over time. The proportion of FIT ≥10µgHb/g was lower in regions with higher rates of testing, from 16.7% (Southwest) to 25.3% (Southeast; rates of testing 14.62 and 8.00 per thousand person-years respectively). This difference in proportion of FIT ≥10µgHb/g persisted after adjusting for year, sex and age (OR 0.57, 95% CI 0.55-0.58).

Conclusion: Rapid increases in FIT testing in primary care show large, persistent variations between English regions, which correlate with the proportion of results meeting the criteria for onward referral. Differences in the population tested and FIT's implementation between regions are likely to explain these variations.