About risk factors

These statistics represent the number of people in the federal electorate division living with each of four known risk factors for stroke. These numbers are not cumulative as people may suffer from two or more of these conditions. The high blood pressure, high cholesterol and physical inactivity numbers have been calculated based on data from the 2011-12 Australian Health Survey released by the Australian Bureau of Statistics. The atrial fibrillation rates are based on data from a 2011 Deloitte Access Economics report.

High blood pressure

Around 4.7 million Australians have high blood pressure. High blood pressure is a leading risk factor for stroke. The World Health Organization and the National Heart Foundation of Australia defines ‘high’ blood pressure as systolic pressure at or above 140mmHg. ^{1, 2}

Major contributors to high blood pressure include poor diet (especially high salt intake), being overweight, excessive alcohol consumption and insufficient physical activity.

Research suggests that 48% of strokes could be prevented if high blood pressure was eliminated. Lowering blood pressure has been conclusively shown to prevent both ischaemic and haemorrhagic strokes, and it is equally important in secondary prevention. ³

References

1. National Heart Foundation. Blood pressure and your heart. Available at: https://www.heartfoundation.org.au/heart-health-education/blood-pressure-and-your-heart.
2. World Health Organization. Hypertension (September 2019). Available at: https://www.who.int/newsroom/fact-sheets/detail/hypertension.
3. Martin O’Donnell et al. ‘Global and regional effects of potentially modifiable risk factors associated with acute stroke in 32 countries (INTERSTROKE): a case-control study’. (2016). Lancet. 388(1): 761-765.

Atrial fibrillation

Almost 385,000 Australians have an irregular heartbeat known as atrial fibrillation. The prevalence of atrial fibrillation increases with age, affecting around 1 in 5 people aged 85 years or older. Atrial fibrillation is associated with one in four strokes. ¹

Like high blood pressure, many people are unaware they suffer from atrial fibrillation and how serious the condition is. As a consequence, too few people are accessing life-saving treatments to control atrial fibrillation.

References

1. National Stroke Foundation. Atrial Fibrillation. Available at: https://strokefoundation.org.au/About-Stroke/Prevent-Stroke/Atrial%20fibrillation.

High cholesterol

Almost 2.5 million Australians live with high cholesterol. High cholesterol is defined as total cholesterol greater than or equal to 5.5 mmol/L. ¹ High cholesterol contributes to blood vessel disease, which often leads to stroke. High-density lipoprotein (‘good’) cholesterol helps to reduce cardiovascular disease risk, while low-density lipoprotein (‘bad’) cholesterol can increase risk.

Cholesterol comes from two sources – the food we eat (of which only 50 percent of the cholesterol may be absorbed) as well as that synthesised and metabolised in the body, mainly the liver, which is by far the greater amount. High cholesterol levels have been associated with ischaemic stroke – those caused by clots. Statins (a group of medicines that can help lower the level of bad cholesterol in the blood) are demonstrated to reduce the risk of stroke by about 20 percent.

References

1. Australian Bureau of Statistics. National Health Survey: First Results, 2017-18 (Catalogue No. 4364.0.55.001, 12th December 2018). Available at: https://www.abs.gov.au/ausstats/abs@.nsf/mf/4364.0.55.001.

Physical inactivity

Over 3.1 million Australians, or around 12% of the Australian population report no physical activity within the past week. ¹ There are also many more Australians who do not meet the National Physical Activity Guidelines which recommend 2.5-5 hours of moderate physical activity or 1.25-2.5 hours of vigorous physical activity each week, with an aim to be active on most days of the week. ²

Insufficient physical activity may be linked to stroke, as well as other risk factors considered in this report such as being overweight or obese, high blood pressure and high cholesterol.

References

1. Australian Bureau of Statistics. National Health Survey: First Results, 2017-18 (Catalogue No. 4364.0.55.001, 12th December 2018). Available at: https://www.abs.gov.au/ausstats/abs@.nsf/mf/4364.0.55.001.
2. Department of Health. Australia’s Physical Activity and Sedentary Behaviour Guidelines and the Australian 24-Hour Movement Guidelines (April 2019). Available at: https://www1.health.gov.au/internet/main/publishing.nsf/content/health-pubhlth-strateg-physact-guidelines.

Daily smoking

Around 2.8 million Australians smoke on a daily basis. Smoking is a significant risk factor of stroke, with the Australian Burden of Disease Study estimating that smoking is attributable to 11% of the total burden of stroke. ¹ Smoking increases the likelihood of dying as a result of stroke, while a ‘pack a day’ smoker is more than six times as likely to have a stroke compared to a non-smoker. ²

Smoking has several effects on the body, including thickening the blood, increasing the risk of blood clots and thinning the arteries. Smoking also limits the amount of oxygen in the blood.

References

1. Australian Institute of Health and Welfare. Australian Burden of Disease Study: impact and causes of illness and death in Australia 2015 (June 2019). Available at: https://www.aihw.gov.au/reports/burden-of-disease/burden-disease-study-illness-death-2015/contents/table-of-contents.
2. Stroke Association. Smoking and the risk of stroke (September 2017). Available at: https://www.stroke.org.uk/sites/default/files/smoking_and_the_risk_of_stroke.pdf.

Overweight and obesity

More than 1 in 2 Australians are overweight or obese, with an estimated 13.8 million overweight or obese Australians in 2020. Overweight and obese Australians were defined by a body mass index of >25 (with a score of >30 representing obese Australians). Overweight and obesity are prevalent across all ages, though the likelihood peaks at around 60 years of age. At this age, more than 80% of men and 70% of women were overweight or obese. ¹

Obesity or being overweight can contribute to other risk factors including high blood pressure and high cholesterol which heighten the risk of stroke.

References

1. Australian Bureau of Statistics. National Health Survey: First Results, 2017-18 (Catalogue No. 4364.0.55.001, 12th December 2018). Available at: https://www.abs.gov.au/ausstats/abs@.nsf/mf/4364.0.55.001.