For the first time, air pollution emerges as a leading risk factor for stroke worldwide

THE LANCET

The findings, from an analysis of global trends of risk factors for stroke between 1990-2013, also show that over 90% of the global burden of stroke is linked to modifiable risk factors, most of which (74%) are behavioural risk factors such as smoking, poor diet and low physical activity. The authors estimate that control of these risk factors could prevent about three-quarters of all strokes. IMAGE/Stock

The findings, from an analysis of global trends of risk factors for stroke between 1990-2013, also show that over 90% of the global burden of stroke is linked to modifiable risk factors, most of which (74%) are behavioural risk factors such as smoking, poor diet and low physical activity. The authors estimate that control of these risk factors could prevent about three-quarters of all strokes.

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 population-attributable fraction (PAF) of stroke-related disability-adjusted life years (DALYs) — ie. the estimated proportion of disease burden in a population that would be avoided if exposure to a risk factor were eliminated.

Every year, approximately 15 million people worldwide suffer a stroke — of these, nearly six million die and five million are left with permanent disability. Disability may include loss of vision and/or speech, paralysis and confusion.

Globally, the ten leading risk factors for stroke were high blood pressure, diet low in fruit, high body mass index (BMI), diet high in sodium, smoking, diet low in vegetables, environmental air pollution, household pollution from solid fuels, diet low in whole grains, and high blood sugar. About a third (29.2%) of global disability associated with stroke is linked to air pollution (including environmental air pollution and household air pollution). This is especially high in developing countries (33.7% vs 10.2% in developed countries).

In 2013, 16.9% of the global stroke burden was attributed to environmental air pollution (as measured by ambient particle matter [PM] pollution of aerodynamic diameter smaller than 2·5 ?m) — almost as much as that from smoking (20.7%). From 1990 to 2013, stroke burden associated with environmental air pollution (PM25) has increased by over 33%.

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