Study: 25% of adults worldwide will have a stroke

About one-quarter of adults in the world will experience a stroke in their lifetime, according to new estimates from the Global Burden of Disease Study (GBDS) published online Dec. 20 in the New England Journal of Medicine.

The GBDS 2016 used all available epidemiologic data to assess health loss from 328 diseases across 195 countries and territories from 1990 through 2016. With this information, corresponding author Gregory A. Roth, MD, and colleagues sought to calculate the cumulative lifetime incidence of a first stroke—including ischemic or hemorrhagic strokes—among adults 25 or older.

After adjusting for competing causes of death, they found 24.9 percent of people from the age of 25 onward could be expected to have a stroke in their remaining lifetimes. That 2016 proportion is up from the 22.8 percent estimate from 1990, representing a relative increase of 8.9 percent. Estimates weren’t significantly different for men (24.7 percent) versus women (25.1 percent).

“This increase (from 1990 to 2016) is the result of unchanged or increasing stroke incidence in many middle-SDI (sociodemographic index) countries and declines in the competing risks of death from any cause other than stroke,” noted the authors, who added that the risk of ischemic stroke changed more during that timeframe than the risk of hemorrhagic stroke.

Other notable findings from the study include:

  • The regions with the highest lifetime risks of stroke were East Asia (38.8 percent), Central Europe (31.7 percent) and Eastern Europe (31.6 percent), while eastern sub-Saharan Africa had the lowest risk (11.8 percent).
  • Among countries, China had the highest estimated risk at 39.3 percent.
  • The global lifetime risk of ischemic stroke was 18.3 percent and the lifetime risk of hemorrhagic stroke was 8.2 percent.
  • High-middle SDI countries carried the highest risk of stroke at 31.1 percent. High-SDI countries were next with a 23.5 percent average, while low-SDI countries had the lowest risk at 13.2 percent.

On this last calculation, the authors said the lower risk in those impoverished countries was because of a higher likelihood of death from other causes prior to stroke occurring, “and does not necessarily represent a lower incidence of stroke or more effective prevention and treatment strategies.”

Individuals of both sexes maintained a similar lifetime risk of stroke from age 25 to 70, but the remaining risk of stroke diminished at more advanced ages because competing causes of death became more prevalent. For example, the average risk of experiencing stroke dropped to 13.4 percent among 95-year-olds.

“Estimates of lifetime risk of stroke may be useful for the long-term planning of health systems,” wrote Roth, with the University of Washington’s Institute for Health Metrics and Evaluation, and coauthors. “In addition, estimates of lifetime risk of stroke across the age spectrum on a national level may be useful for gauging the effect of stroke prevention strategies.”

Roth et al. specified that their analysis was estimating the lifetime incidence of first-ever strokes and didn’t account for recurrent strokes. They said the accuracy of their results relied upon the accuracy and availability of the epidemiologic data captured from different countries. For those with insufficient data, statistical models using data from neighboring countries and country-level risk exposures were used to calculate the estimates.