Is the Framingham coronary heart disease absolute risk function applicable to Aboriginal people?

To the Editor: Wang and Hoy1 deserve much credit for highlighting yet again the poor state of health of Indigenous Australians. However, their conclusion that the Framingham equation underestimated risk and that better prediction equations are needed may miss the point.

The Framingham equations work well in other populations if the aim is to rank groups of individuals into higher or lower risk categories. Box 4 in the article by Wang and Hoy shows that they do this pretty well across increasing age groups. Framingham equations fall down when they are used to estimate absolute risk in populations whose coronary heart disease (CHD) rates are different from those in the Framingham study. Some years ago, we showed that adjusting the Framingham risk estimates in line with the overall incidence of CHD in the population modestly improved their performance.2

This is all very nice, but is better risk estimation the solution? We don’t estimate risk in other high-risk groups (eg, patients with CHD), because all are at high risk and all need risk factor reduction. A brief look at the risk factor profile in Box 2 of Wang and Hoy’s article reveals an alarming picture of uncontrolled CHD risk factors in a relatively young population (average age, 33–36 years). Cigarette smoking, dyslipidaemia, diabetes and overweight prevail.

Perhaps, rather than concentrating on quantifying the exact risk in such a high-risk population, we should look at the reasons for the high rates of risk factors. What motivates some Indigenous people to smoke more, be more overweight and have a higher incidence of dyslipidaemia and diabetes than other Australians?3,4 Do they feel disenfranchised when governments infer they are “dirty” by tying financial aid to face-washing?5 Do they have attractive employment opportunities? Do they have enough sense of control over their lives to reduce their need to indulge in cigarettes and other short-term pleasures? Are there adequate supplies of healthy foods that they like? These factors may differ, as some rural Abori-ginal communities have much lower rates of smoking, overweight and diabetes6 than others. Exploring these issues will aid preventive methods aimed at the whole community.

In the meantime, I would suggest that the Framingham equation does rank members of this community — into modest, high, and very high risk (the average 45–54-year-old has a 20% risk of a CHD event over 10 years1). This may help guide the medical treatment of risk factors and the pursuit of the medical model of prevention while social changes dictated by Aboriginal communities take effect.