From 1990 to 2019, the annual number of strokes and stroke-related deaths significantly increased worldwide, with high body mass index (BMI) representing the fastest-growing risk factor for strokes during this period, according to the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) findings published in The Lancet Neurology.
GBD data provides a standardized and comprehensive view on stroke and its pathological types, risk factors, and trends to help guide evidence-based health care policy and resource allocation for stroke. The current study authors sought to provide updated estimates on global, regional, and national burden of overall stroke, ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage based on age, sex, and country income level from the past 3 decades. This is the first GBD report to provide the global, regional, and national burden of intracerebral hemorrhage and subarachnoid hemorrhage separately, according to the study authors.
The current study calculated stroke incidence, prevalence, mortality, disability-adjusted life-years (DALYs), and population attributable fraction of DALYs associated with stroke risk factors across 204 countries and territories from 1990 to 2019. Estimates were made for ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, and all strokes combined. All estimates were also stratified by sex, age, and World Bank country income level.
The number of incidence cases of stroke, prevalent cases of stroke, DALYs due to stroke, and deaths due to stroke were 12.2 million (95% UI, 11.0–13.6), 101 million (95% UI, 93.2–111), 143 million (95% UI, 133–153), and 6.55 million (95% UI, 6.00–7.02), respectively. Across the globe, stroke was the second-leading cause of mortality in 2019 (11.6%; 95% UI 10.8–12.2) as well as the third-leading cause of both mortality and disability (5.7%; 95% UI, 5.1–6.2).
According to the researchers, the absolute number of incident strokes increased by 70.0% (95% UI, 67.0–73.0) from 1990 to 2019. During the study period, the absolute number of prevalent strokes increased by 85.0% (95% UI, 83.0–88.0), deaths from stroke increased by 43.0% (95% UI, 31.0–55.0), and DALYs due to stroke increased by 32.0% (95% UI, 22.0–42.0).
From 1990 to 2019, the age-standardized stroke incidence rates declined by 17.0% (95% UI, 15.0–18.0), mortality reduced by 36.0% (95% UI, 31.0–42.0), prevalence decreased by 6.0% (95% UI, 5.0–7.0), and DALYs reduced by 36.0% (95% UI, 31.0–42.0). Despite these reductions, prevalence and incidence rates increased by 22.0% (95% UI, 21.0-24.0) and 15.0% (95% UI, 12.0-18.0), respectively, in individuals <70 years of age.
The 2019 age-standardized stroke-related mortality rate was approximately 3.6 (95% UI, 3.5–3.8) times higher in the World Bank low-income group compared with the World Bank high-income group. Additionally, the age-standardized stroke-related DALY rate was up to 3.7 (95% UI, 3.5–3.9) times higher in the low-income group compared with the high-income group.
In 2019, 62.4% of all incident strokes were attributable to ischemic stroke (7.63 million), while 27.9% were attributable to intracerebral hemorrhage (3.41 million) and 9.7% were attributable to subarachnoid hemorrhage (1.18 million). The 5 leading risk factors for stroke in 2019 included high systolic blood pressure (79.6 million DALYs or 55.5% of total stroke DALYs), high BMI (34.9 million DALYs or 24.3% of total stroke DALYs), high fasting plasma glucose (28.9 million DALYs or 20.2% of total stroke DALYs), ambient particulate matter pollution (28.7 million DALYs or 20.1% of total stroke DALYs), and smoking (25.3 million DALYs or 17.6% of total stroke DALYs).
The study was limited by the lack of other important risk factors for stroke, including atrial fibrillation and substance abuse.
The researchers wrote that “closing the gaps between high-income countries and low-income and middle-income countries in the adaptation and implementation of internationally” recognized guidelines “for reducing stroke morbidity and mortality, with an emphasis on primary prevention strategies, is crucial to addressing the global stroke burden.”
Disclosure: This clinical trial was supported by Bill & Melinda Gates Foundation. Multiple authors declared affiliations with the pharmaceutical industry. Please refer to the original article for a full list of disclosures.
GBD 2019 Stroke Collaborators. Global, regional, and national burden of stroke and its risk factors, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet Neurol. Published online September 3, 2021. doi:10.1016/S1474-4422(21)00252-0