“Air Pollution is as Dangerous as Smoking”… 23 Factors That Cause Stroke

An analysis has shown that the number of stroke patients worldwide has increased significantly between 1990 and 2021. The research team emphasized that while the burden of stroke has increased significantly worldwide due to population growth and aging, preventable risk factors have also increased the rate of increase, and that all countries must urgently implement effective prevention strategies.

The researchers estimated the annual incidence and prevalence rates, mortality rates, and disability-adjusted life years (DALYs) per 100,000 people for overall stroke, ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage in 204 countries and territories from 1990 to 2021. They also calculated the stroke burden attributable to 23 risk factors and six risk clusters (air pollution, smoking, behavioral factors, dietary factors, environmental factors, and metabolic risks).

According to the analysis, the number of new stroke patients worldwide in 2021 was 11.9 million, a 70% increase since 1990, and the number of stroke-related deaths increased by 44% to 7.3 million, making stroke the third leading cause of death worldwide after ischemic heart disease and COVID-19. In addition, the loss due to disability, disease, and premature death caused by stroke was analyzed to have increased by 32%.

By subtype, ischemic stroke accounted for 65.3% of all strokes, intracerebral hemorrhage accounted for 28.8%, and subarachnoid hemorrhage accounted for 5.8%.

There were differences in the burden and risk factors of stroke by country and region. In addition, the decline in incidence rates since 2015 showed a stagnant trend, and the incidence, mortality, prevalence, and disability-adjusted survival years of stroke in Southeast Asia, East Asia, Oceania, and the population under 70 years of age actually increased somewhat.

The results of the analysis by risk factor showed that the risk factors that contributed to the stroke burden between 1990 and 2021 were high body mass index, high temperature, high blood sugar, high sugar-sweetened beverage intake, lack of physical activity, high systolic blood pressure, and low intake of omega-6 polyunsaturated fatty acids.

However, it was shown that there was considerable progress in reducing the burden of stroke caused by bad eating habits, air pollution, and smoking. The health loss due to high consumption of processed meat and low consumption of vegetables decreased by 40% and 30%, respectively, and the result showed that the reduction due to fine dust air pollution decreased by 20% and the reduction due to smoking decreased by 13%.

This analysis found that ambient particulate matter air pollution contributed 14% to deaths and disabilities due to subarachnoid hemorrhage, demonstrating that air pollution is a risk factor at the same level as smoking.

“The number of people developing stroke, dying or being disabled as a result of stroke is rising rapidly worldwide, which strongly suggests that current stroke prevention strategies are not sufficiently effective,” said study author Professor Valerie L. Feigin from Auckland University of Technology in New Zealand. “New prevention strategies that have been proven effective for all people at risk of stroke, regardless of risk level, must be implemented globally as an urgent priority.”

“Because 84 percent of the stroke burden is associated with just 23 modifiable risk factors, we have a tremendous opportunity to change the trajectory of stroke risk in the next generation,” said study co-author Catherine O. Johnson, PhD, a senior research scientist at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington. “Given that ambient air pollution is interconnected with temperature and climate change, the importance of actions to reduce air pollution cannot be overstated, and interventions focused on obesity and metabolic syndrome are urgently needed as exposure to risk factors such as high blood sugar and high sugar-sweetened beverage consumption increases.” She added, “Working with communities to find sustainable ways to take action to prevent and control modifiable risk factors for stroke is essential to addressing this growing crisis.”

The new analysis from the Global Burden of Disease, Injuries, and Risk Factors Study (GBD) was published in The Lancet Neurology and will be presented at the World Stroke Congress in Abu Dhabi in October.