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How NZ's cardiovascular disease-risk assessment is 'leading the world'

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Cardiovascular disease is our biggest killer, but risk assessment and treatment are improving.

For years, our risk of cardiovascular disease was assessed using information gleaned from the Framingham Heart Study. Since 1948, thousands of residents in this small Massachusetts town have had their medical histories and lifestyle scrutinised. Key risk factors such as high blood pressure and cholesterol, smoking, obesity and diet have been identified as a result of data gathered from three generations.
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The research has been valuable, but as the people of Framingham are predominantly white, it’s been questionable as to how well they represent New Zealand’s more diverse population. There were also concerns the old assessment charts were outdated. So now New Zealand is making a change, with the development of new cardiovascular disease-risk assessment and treatment guidelines based on our health statistics.

“We are leading the world here,” says Gerry Devlin, the Ministry of Health’s cardiac adviser and the Heart Foundation medical director, who co-chaired the process that led to the new guidelines.

The update is based on data from epidemiologist Rod Jackson and his team at the University of Auckland. They developed Predict, an algorithm for calculating heart-attack risk, and have gathered information from more than half a million New Zealanders in GP care.

Dr Gerry Devlin.

The computerised Predict chart gives each person a score: your percentage chance of a cardiovascular event in the next five years. It assesses overall risk, rather than looking at such factors as cholesterol and blood pressure in isolation.

So, what has changed as a result of this new information? Well, high-risk groups are being advised to get assessed earlier. Māori, Pasifika and South Asian people should begin screening at age 30 for men and 40 for women – that’s 15 years sooner than the rest of the population. Severe mental illness has also been shown to significantly increase the chance of a heart attack, so screening is recommended for sufferers from age 25.

“What is really important is that it’s not just about risk assessment but what happens after that,” says Devlin.

Those scored as having a 15% or above chance of a heart attack in the next five years are considered high risk and should be looking at taking medication to lower blood pressure and cholesterol, making lifestyle changes, and returning to their doctor for an annual check-up. With scores from 5%-14%, the risk is rated as moderately increased, which means it’s time to weigh up the benefits of medication with a health professional and improve diet, become more active and quit smoking.

Professor Rod Jackson. Photo/David White

If drugs are prescribed, there are now treatment targets. Blood pressure should fall ideally to 130/80 or below. And the level of “bad” cholesterol LDL should be reduced to 1.8.

Those assessed as in the moderate-risk category are advised to return to their doctor for a check-up every two to five years. And even if you’re low-risk – scoring under 3% – you should get screened again after 10 years.

Devlin adds that monitoring blood pressure has been identified as one area that needs improvement. Lots of us will have had that experience of rushing into our doctor’s surgery, powered by a couple of coffees, and being “let off” having slightly raised blood pressure. Devices that monitor at regular intervals over 24 hours will provide a more accurate reading.

Cardiovascular disease remains this country’s leading cause of death, and in recent years there has been a rise in the number of us who are living with heart disease. It increased from 172,000 in 2015/16 to 189,000 in 2016/17, which continues a trend seen in the previous couple of years. A number of factors may be contributing – we have an ageing population and are becoming fatter and more sedentary, and many are eating less healthily.

Says Devlin, “The only thing that’s decreased is smoking.”

This article was first published in the March 3, 2018 issue of the New Zealand Listener.