Background There are several calculators available internationally for predicting risk of cardio-vascular disease based on an individual’s particular risk factors. Ethnicity is associated with risk of cardio-vascular disease. We studied 10 important calculators and considered (a) whether ethnicity was included as a risk factor (b) which ethnic groups were included within each calculator; and (c) the mathematics by which ethnicity was incorporated.

Methods Ten commonly used calculators were identified by examining the literature and searching risk prediction websites and examined in detail through both the published literature and online technical descriptions. Their component risk factors were tabulated and a comparison made.

Results Of the ten calculators examined, seven did not include ethnicity as a risk factor. Those seven calculators that excluded ethnicity, included risk factors which have the potential to account for some of variation in risk associated with ethnicity

In the three calculators that included ethnicity, there is variation as to which ethnic groups are considered, and this probably reflects geographic variation in the important ethnic groups for that country or region.

In the three calculators that included ethnicity as an additional risk factor, there was inconsistency in the mechanism by which ethnicity was incorporated. In one it was a fixed additive term, in another it was a full interaction with other risk factors presented as a distinct model. In the third an additive term but with an upper bound of risk meaning implying ethnicity interacts with other risk factors.

Conclusion Ethnicity is often not always included and when it is it is included it is done so in different ways in different calculators. This diversity suggests that there remains uncertainty as to what and how risk factors should be included and that ethnicity itself isn’t agreed as an essential additional variable. Refinement of calculators will likely arise as the acquisition of prospective multi-ethnic data sets improves.