Air pollution is as a leading risk factor for stroke, researchers report today.
An analysis of global trends of risk factors for stroke between 1990-2013 showed while more than 90% of the global burden of stroke is linked to modifiable risk factors, such as smoking, poor diet and low physical activity, in 2013, air pollution was associated with about one third of the global burden of stroke.
Writing in The Lancet Neurology, the authors estimate that controlling these risk factors could prevent about 75% of all strokes.
Using 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 population-attributable fraction (PAF) of stroke-related disability-adjusted life years (DALYs).
The leading risk factors for stroke were high blood pressure, a diet low in fruit, vegetables and whole grains, a diet high in sodium, high body mass index (BMI), smoking, environmental air pollution, household pollution from solid fuels, and high blood sugar.
About a third (29.2%) of global disability associated with stroke is linked to air pollution, which includes environmental air pollution and household air pollution. Between 1990 and 2013, the stroke burden associated with environmental air pollution (PM25) rose by more than 33%.
“A striking finding of our study is the unexpectedly high proportion of stroke burden attributable to environmental air pollution, especially in developing countries,” said lead author Professor Valery L Feigin, of Auckland University of Technology, New Zealand.
“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.”
He said the findings could help national governments and international agencies to develop and prioritise public health programmes and policies, including legislation and taxation of tobacco, alcohol, salt, sugar or saturated fat content.
“Taxation has been proven to be the most effective strategy in reducing exposure to smoking and excessive intake of salt, sugar and alcohol,” he continued.
“If these risks take a toll on our health, and taxation is the best way to reduce exposure to these risks, it logically follows that governments should introduce such taxation and reinvest the resulting revenue back into the health of the population by funding much needed preventative programmes and research in primary prevention and health. All it takes is recognition of the urgent need to improve primary prevention, and the good will of the governments to act.”
According to the analysis, household air pollution was greater risk factor for stroke in central, eastern, and western sub-Saharan Africa and south Asia compared to North America, central, eastern and western Europe.
Low physical activity was a greater risk factor for stroke among adults over 70 than among adults aged 15-69, while the risk factor that was most reduced between 1990 and 2013 was second-hand smoke, which dropped by 31%.
The risk factor that saw the greatest rise was a diet high in sugar-sweetened drinks (63.1% increase in stroke-related DALYs).
Because of a lack of data, the authors were unable to include some important risk factors for stroke such as atrial fibrillation, substance abuse or other health conditions and they could not account for patterns of some risk factors such as levels of smoking, BMI level or underlying genetic risk factors.
The data does not differentiate between ischaemic and haemorrhagic stroke.
Feigin VL, Roth GA, Naghavi M et al. Global burden of stroke and risk factors in 188 countries, during 1990–2013: a systematic analysis for the Global Burden of Disease Study. Lancet Neurol 9 June 2016 [abstract]
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