What is the epidemiology of ischemic stroke?

Epidemiology of Ischemic Stroke

Ischemic stroke affects approximately 795,000 individuals annually in the United States, representing 87% of all strokes, with approximately 185,000 being recurrent events 1.

Global Burden

The worldwide impact of ischemic stroke is substantial and growing:

• In 2021, there were 7.8 million incident cases globally, with an age-standardized incidence rate of 92.4 per 100,000 population 2
• Prevalence reached 69.9 million cases in 2021, with an age-standardized prevalence rate of 819.5 per 100,000 3
• Stroke remains the second-leading cause of death globally (11.6% of total deaths) and third-leading cause of death and disability combined 4

From 1990 to 2021, absolute numbers increased dramatically—incident strokes rose by 70%, prevalent strokes by 85%, and deaths by 43%—despite declining age-standardized rates 4. This paradox reflects population aging and growth rather than worsening disease control.

United States Epidemiology

The domestic burden is equally concerning:

• Someone in the United States has a stroke every 40 seconds, and someone dies of stroke every 4 minutes 5
• Approximately 7.2 million Americans ≥20 years have had a stroke 5
• 22.5% of the population >45 years reports stroke symptoms, TIA, or stroke history 5
• Projections estimate an additional 3.4 million US adults ≥18 years will have had a stroke by 2030, with the highest increase (29%) in Hispanic men 5

Key Demographic Patterns

Age Distribution

Among people younger than 70 years, prevalence rates increased by 22% and incidence rates by 15% from 1990 to 2019, indicating a concerning shift toward younger populations 4.

Sex Differences

The disease burden is consistently higher in males than females across all age groups 6.

Racial and Ethnic Disparities

• Blacks are more likely to report stroke symptoms than whites 5
• Those with lower income and lower education are more likely to report stroke symptoms 5

Geographic Variations

The highest incidence rates occur in developing nations and post-Soviet countries 7. Regionally:

• Eastern Europe shows the highest age-standardized incidence rates 3
• North Macedonia has the highest incidence, mortality, and DALY rates among 204 countries 2
• From 2014-2021, the Caribbean experienced the fastest increase in age-standardized incidence (annual percent change = 0.15) 2

Socioeconomic Impact

The age-standardized stroke-related mortality rate is 3.6 times higher in World Bank low-income countries compared to high-income countries, with DALY rates 3.7 times higher 4. This inverse relationship between GDP and stroke burden underscores the role of healthcare access and prevention resources 2.

In 2015, the estimated total cost for stroke in the United States was $66.3 billion, projected to increase to $143 billion by 2035 5.

Modifiable Risk Factors

90.5% of the global stroke burden is attributable to modifiable risk factors 1. The top five risk factors contributing to stroke DALYs in 2019 were:

1. High systolic blood pressure (55.5% of stroke DALYs) 4
2. High body-mass index (24.3%) 4
3. High fasting plasma glucose (20.2%) 4
4. Ambient particulate matter pollution (20.1%) 4
5. Smoking (17.6%) 4

Notably, high body-mass index was the fastest-growing risk factor for stroke between 1990 and 2019 4.

The INTERSTROKE study demonstrated that five factors—blood pressure, diet, physical inactivity, smoking, and abdominal obesity—accounted for 82% of the population-attributable risk for ischemic stroke 1.

Recurrence Risk

The risk of recurrent stroke is highest in the first 90 days after initial event, with 12% of patients experiencing recurrence within 5 years 8. However, cohort studies show reduction in recurrent stroke rates in recent years as secondary prevention strategies have improved 1.

Recurrence frequency varies by clinical stroke subtype: POCI (20-25%), TACI and PACI (17%), and LACI (9%), with most recurrent strokes occurring in the same cerebral artery as the primary event 7.

COVID-19 Impact

The COVID-19 pandemic significantly changed the epidemiology of ischemic stroke, with a sharp increase in rates observed during 2020-2021 6. This underscores the need for continued surveillance in the post-pandemic era.

Future Projections

Without urgent implementation of effective primary prevention strategies, the stroke burden will continue to grow across the world, particularly in low-income countries 4. Disease burden projections for China suggest continued growth from 2021 to 2030 6, a pattern likely to be replicated globally given demographic trends.