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Why heart age calculators should be used with caution

7 February 2018
Researchers warn heart age calculators could be misleading
Online heart age and heart disease risk calculators are widely used but often misleading for the average person, new research from the University of Sydney reveals.

New research published today in Bio-Med Central has found online heart age calculators to be misleading, reinforcing research published last week in the Journal of Medical Internet Research that found online heart disease risk calculators are also misleading.

Heart disease risk calculators use risk factors like blood pressure and cholesterol to predict one’s chance of having a heart attack or stroke in the next five to 10 years.

Heart age calculators compare one’s risk factors to ideal or average levels for one’s age, to indicate whether one’s heart age is older or younger than one’s current age.

For example, these calculators could return results claiming that a 57-year-old woman with elevated cholesterol has a four percent elevated risk of heart disease over a five-year period and a heart age of 64 years.

The research found that online heart disease risk calculators were misleading, producing both false positives and false negatives, meaning that low heart disease risk patients could be medicated unnecessarily and high risk patients not seeking further assessment by a doctor. The results were also hard to understand for patients and provided little recommendation for further treatment.

Lead author of both studies, Dr Carissa Bonner from the University of Sydney’s School of Public Health, said there is a large variation in the results produced by heart age calculators and that even if a patient was shown to have an older heart age than their current age, their risk of heart attack or stroke may still be low.

“Heart age calculators are increasingly popular and four in five people have an older heart age than their current age. But if you want to know how you can reduce your risk of a heart attack or stroke, talk to your GP about assessing your heart disease risk, not your heart age,” she said.

Dr Bonner said heart disease risk was a better indicator of future health than heart age and allowed treatment to be targeted at those with the highest risk, who are more likely to benefit from medication.

“Having an older heart age just means that at least one of your risk factors is higher than the level set to be “normal” by the calculator. It doesn’t indicate the need for treatment. Knowing the heart disease risk means patients can be prescribed medications based on their level of risk, which is a more direct measure of future heart health.

“People cannot make an informed decision based on heart age because there is no clear relationship between older heart age and medication benefit,” she said.

When it comes to measuring heart disease risk, online calculators are perhaps not the way to go according to Dr Bonner, who’s research team recently investigated a range of calculators.

In the study, the researchers entered the same high-risk patient profile into 73 online calculators that predicted the risk of a future heart attack or stroke. The results ranged widely, claiming an increased risk of between three and 43 per cent of developing cardiovascular disease in the next 10 years.

Dr Bonner said misleading results could lead to adverse consequences for patients.

“Low risk patients may be unnecessarily alarmed by results that look high risk without adequate explanation, while high risk patients may not realise they are high risk and should see a GP for a more formal assessment and advice.”

Dr Bonner said the calculators lacked clear information to help patients understand their results and whether they should be altering their lifestyle or considering medication.

“The calculators scored ‘moderately’ on understandability and ‘poorly’ on actionability. This means it would be hard for the average person to understand the risk results without more information – are they at low or high risk, should they change their lifestyle, or do they need to see their GP about medication right away?”

The research found that the better risk calculators provide:

    - Information about how the assessment was calculated with endorsement from a reputable organisation such as the Heart Foundation.

    - A clear explanation of the risk result in verbal (e.g. moderate risk), numerical (eg, 12 per cent risk of a heart attack in the next five years), and graphical formats (eg, a pictograph that illustrates the percentage in terms of frequency).

    - Explicit actions that could be taken to reduce this risk (including lifestyle and medication options) and advice about when and why a GP’s guidance would be needed.

“There are good risk calculators out there, but it is not easy for the average person to find the best one that is reliable and easily understood from a Google search.

“Most countries use a specific clinical risk model that is relevant to that country’s population, so a good place to start is with the one that your national Heart Foundation endorses,” said Dr Bonner.

For Australians, the Heart Foundation recommends GP assessment for most people over 45 years old, or 35 years old for Aboriginal or Torres Strait Islanders who have a higher risk than non-Indigenous Australians. The Australian Heart Foundation risk calculator is available here

Elliott Richardson

Assistant Media Advisor (Medicine, Dentistry, Nursing and Pharmacy)