Air Pollution is a Leading Stroke Risk Factor

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

The results showed that 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. Overall, 29.2% of the global disability associated with stroke was linked to air pollution, including environmental air pollution and household air pollution. This is especially high in developing countries (33.7%), when compared to developed countries (10.2%).

Household air pollution was a more important risk factor for stroke in Central, Eastern, and Western sub-Saharan Africa and South Asia, compared to North America, Central, Eastern, and Western Europe, where it was not in the top 10 risk factors. The risk factor that was most reduced between 1990 and 2013 was second-hand smoke (31%). The greatest reduction was in developed countries, but the contribution of second-hand smoke to global stroke burden still remains noticeable at 3.1% for 15-49 year olds, especially in developing countries.

The risk factor that was most increased was a diet high in sugar-sweetened beverages (63.1% increase in stroke-related DALYs), with the greatest increase being in developed countries, but the contribution to stroke burden remained low at 1.6% for 15-49 year olds. 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. The study was published on June 9, 2016, in The Lancet Neurology.

“Taxation has been proven to be the most effective strategy in reducing exposure to smoking and excessive intake of salt, sugar, and alcohol,” said lead author Professor Valery Feigin, MD, PhD. “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.”

The authors added that because of a lack of data, they could not include some important risk factors for stroke such as atrial fibrillation (AF), substance abuse, or other health conditions. They were also unable to account for patterns of some risk factors such as levels of smoking, BMI level, or underlying genetic risk factors. Additionally, the data does not differentiate between ischemic and hemorrhagic strokes, but the authors say that while risk factors for different types of stroke may vary slightly at the individual level, global, regional, and national policies tend to look at the overall risk of stroke.

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Auckland University of Technology
Institute for Health Metrics and Evaluation