Faecal haemoglobin concentrations vary with sex and age, but data are not transferable across geography for colorectal cancer screening

Background: Faecal immunochemical tests (FIT) are becoming widely used in colorectal cancer (CRC) screening. Availability of data on faecal haemoglobin concentrations (f-Hb) in three countries prompted an observational study on sex and age and the transferability of data across geography. Methods: Single estimates of f-Hb in large groups were made in Scotland, Taiwan and Italy using quantitative automated immunoturbidimetry on the Eiken OC-Sensor. Distributions were examined for men and women overall and in four different age groups. Results: The distributions of f-Hb were not Gaussian and had kurtosis and positive skewness. The distributions were different in the three countries: f-Hb varies with sex and age in all countries, being higher in men and the elderly, but the degree of variation is inconsistent across countries, f-Hb being higher in Scotland than in Taiwan than in Italy, possibly due to different lifestyles. At any cut-off concentration, more men are declared positive than women and more older people are declared positive than younger individuals. Conclusions: Our analysis supports the view that setting and using a single f-Hb cut-off in any CRC screening programme is far from ideal. We suggest that individualisation is the optimum approach with f-Hb, alone or with other important factors such as sex and age, used to determine important personal issues such as need for colonoscopy, screening interval between tests and risk of future CRC. Whether there is merit in monitoring f-Hb in individuals over time remains an interesting research question for the future.