High levels of risk of heart disease and stroke for Indigenous Australians

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Monday 25 June 2018 5:52PM (view full episode)

Australian's national guidelines currently say heart health screening should begin at age 35 for Aboriginal and Torres Strait Islander people.

However, new research has found there's a high risk of Indigenous people under 35 developing cardiovascular disease.

The study also shows Indigenous people have a higher risk of developing cardiovascular disease in older age.

Researchers say this information will be important to help identify risks earlier, and prevent disease from developing.


Professor Emily Banks

Professor of Epidemiology and Public Health, National Centre for Epidemiology and Population Health, Australian National University, Canberra

Associate Professor Ray Lovett

Head of Aboriginal and Torres Strait Islander Health Program, National Centre for Epidemiology and Population Health, Australian National University, Canberra


Dr Norman Swan


Carl Smith


Norman Swan: For the first time anywhere in the world researchers have assessed what's called the absolute risk of having a fatal or non-fatal heart attack or stroke in an indigenous population. And in this case, it's Australian researchers studying Aboriginal people and Torres Strait Islanders.

Absolute risk is a person's individual chances of a heart attack or stroke in the next five years or so, based on a history of a past heart event, diabetes, or a combination of risk factors like cholesterol levels, blood pressure and smoking. The results have shown that tens of thousands of Aboriginal people are at high risk, some of them quite young, and yet over half are not being treated to reduce their risk.

Heart disease is the biggest cause of the life expectancy gap between Indigenous and non-Indigenous Australians. In our Canberra studio are two of the authors, who are based at the National Centre for Epidemiology and Population Health at the Australian National University: Emily Banks and Ray Lovett. Welcome to you both.

Both: Thank you.

Norman Swan: Emily, why hasn't this been done before?

Emily Banks: Well nobody actually had the large-scale data, so the reason we can do this study is because 2,820 Aboriginal and Torres Strait Islander people across Australia gave information about their experiences via interview. They gave blood samples and they also had their blood pressure checked. And it's because of those data that were collected by the Australian Bureau of Statistics that we can actually do this study, because it was a study that allowed a representative sample to be generated. It just hadn't been done anywhere else in the world.

Norman Swan: Ray Lovett, you're an Aboriginal epidemiologist, what sort of…this is not non-trivial, studying Aboriginal populations, because you have community-controlled organisations, and there are whole ethical things around this. So getting permission to do this must have been significant.

Ray Lovett: Indeed. The scale, the number of people involved that Emily mentioned is tremendous, and while there are always concerns around consent and what people are consenting to, I think the uptake in this instance, or acceptance to participate, was around 84% of Aboriginal and Torres Strait Islander people that were asked to give their samples consented to do that. So Aboriginal people are saying that we want to participate in these studies. We need the evidence, we need the data available so that we have the equivalence of evidence that the non-Indigenous population has, so that we can see how these particular health issues are affecting our mob.

Norman Swan: So what were the findings, Ray?

Ray Lovett: So in your intro you said that some of the findings were that the level of high risk…

Norman Swan: You're about to tell me I got my intro wrong, aren't you?

Ray Lovett: (Laughs) No. You know, that the level of high risk is much greater across all age groups, and in particular that levels of high risk kick in earlier as well—earlier than we previously thought.

Norman Swan: Because previously there's been guidelines which say that your doctor, Aboriginal medical services and so on should really take note of Aboriginal people at the age of about 35 on, but you found it started to kick in at 25, didn't you?

Ray Lovett: That's right. So if we look at the non-Indigenous population and look at the level of high risk, which is around 5% at age 45 years, so if we apply the equivalence test that's exactly where we found that same level of high risk starting at 25 years of age, yeah.

Norman Swan: Emily, what sort of tool did you use—we've spoken about absolute risk on the Health Report a few times, where you actually use an algorithm, you can log in for a computerised version of it and you put in your blood pressure, your smoking, your cholesterol levels and so on. But I understood that there hasn't been a reliable absolute risk tool for Aboriginal populations. Where did you find one?

Emily Banks: So what we did was we used the standard nationally recommended algorithm, which is the National Vascular Disease Prevention Alliance algorithm. And what that does is first of all it sorts out who's already had a previous heart attack or stroke and who hasn't. And then it looks at what we call clinically determined high risks. So it looks at who's got diabetes with microalbuminuria, which albumin in the urine…

Norman Swan: So kidney damage.

Emily Banks: Kidney damage. Who's got very, very high blood pressure, who's got very, very high cholesterol, and other markers of chronic kidney disease. And after you've gone through that..

Norman Swan: And they don't need any absolute risk tool. You're at high risk already…

Emily Banks: That's right. They're already at high risk. And then those people who make it through that and are not classed as high risk in that then have their blood pressure, their cholesterol, smoking data, their age, their sex and whether or not they've got diabetes put in to an algorithm, put into an equation called the Framing and Risk equation. And so all of those things put together allows you to work out who's at high risk of having a heart attack or a stroke in the next five years.

What is interesting in our study was actually that 82% of the Aboriginal people who were classed as being at high risk were at high risk because of their clinical features alone.

Norman Swan: So one simple question would have actually answered the question rather than do something complicated.

Emily Banks: Well interestingly, in order to actually classify whether someone's at high risk you've got to know whether they've got diabetes. You've got to know their HbA1c, you've got to know about their urine, you've got to know about their cholesterol level, their blood pressure, and also you've got to look at their eGFR, so you've got to look at their kidney function. So it's quite complex to go through that first part. But what it does say is that actually we know there are issues with the different equations that are used, but actually we found that most of the Aboriginal people, 82% in fact, were classed that way because of their actual clinical features. And as you went to the younger age groups it was more like 100%.

So what we're actually seeing is early onset of things like diabetes and chronic kidney disease, very high blood pressure, very high cholesterol, that are happening in younger Aboriginal people. And across that overlay is very high rates of smoking. Now we know this is a bad news stories in some ways, but it's an extremely good news story that we have this evidence. We didn't have the evidence before.

Norman Swan: Ray, we're running out of time, but very briefly, only half were on preventive therapy. Once you've got that risk, you know that you need to be on cholesterol reduction and blood pressure reduction regardless of your level of cholesterol and blood pressure. Why are they not being treated? Is it because they're not being identified as high risk?

Ray Lovett: I think that's part of the story, so there's probably a large proportion of people that aren't identified on a routine basis. And then there's also the other things that I guess we don't fully understand from this study about access to services or what kind of treatment regimes are—whether GPs or healthcare providers are implementing best practice treatment approaches.

Norman Swan: So education arises from it. Thank you very much to you both.

Both: Thank you.

Norman Swan: Professor Emily Banks and Associate Professor Ray Lovett are at the National Centre for Epidemiology and Population Health at the Australian National University in Canberra.