A part HRC-funded study* led by AUT University Professor Valery Feigin and recently published in the Lancet Neurology shows that air pollution is now a leading risk factor for stroke worldwide.
Air pollution – including environmental and household air pollution – was associated with about a third of the global burden of stroke in 2013, according to the new study.
The findings, from an analysis of global trends of risk factors for stroke between 1990-2013, also show that more than 90 per cent of the global burden of stroke is linked to modifiable risk factors, most of which (74 per cent) are behavioural risk factors such as smoking, poor diet, and low physical activity.
The study is the first to analyse the global risk factors for stroke in such detail, especially in relation to stroke burden on global, regional, and national levels. The researchers used data from the Global Burden of Disease Study to estimate the disease burden of stroke associated with 17 risk factors in 188 countries. They estimated the proportion of disease burden in a population that would be avoided if exposure to a risk factor were eliminated.
Every year about 15 million people worldwide suffer a stroke – of these, nearly six million die and five million are left with permanent disability.
“A striking finding of our study is the unexpectedly high proportion of stroke burden attributable to environmental air pollution, especially in developing countries,” says Professor Feigin.
“Smoking, poor diet and low physical activity are some of the major risk factors for stroke worldwide, suggesting that stroke is largely a disease caused by lifestyle risk factors. Controlling these risk factors could prevent about three-quarters of strokes worldwide.”
“Our findings are important for helping national governments and international agencies to develop and prioritise public health programmes and policies. Governments have the power and responsibility to influence these risk factors through legislation and taxation of tobacco, alcohol, salt, sugar or saturated fat content, while health service providers have the responsibility to check and treat risk factors such as high blood pressure,” he says.
The relative importance of risk factors varied depending on age group, country and region:
- Household air pollution was a more important risk factor for stroke in central, eastern, and western sub-Saharan Africa and south Asia (ranked 3rd), compared to North America, central, eastern and western Europe (where it was not in the top 10 risk factors)
- Low physical activity was a much greater risk factor for stroke among adults over 70 than among adults aged 15-69
- Air pollution, environmental risks, tobacco smoke, high blood pressure and dietary risks were more important risk factors for stroke in developing countries compared to developed countries.
- Low physical activity was a more important risk factor for stroke in developed countries compared to developing countries.
*This study was funded by the Bill & Melinda Gates Foundation, American Heart Association, US National Heart, Lung, and Blood Institute, Columbia University, Health Research Council of New Zealand, Brain Research New Zealand Centre of Research Excellence, and National Science Challenge, Ministry of Business, Innovation and Employment of New Zealand.