Stroke incidence declines among older adults, remains steady among younger adults

Rates of ischemic stroke and intracerebral hemorrhage remained steady in adults aged 18 to 49 years while decreasing in older adults, particularly in those aged 70 years and older, according to results from a 13-year study.

Stroke mortality also decreased during this period, study findings showed. Researchers published the results in Neurology.

“Stroke remains a leading cause of death and disability worldwide, although estimates from the Global Burden of Disease study showed a decline in incidence rates in high-income countries between 1990 and 2010,” Nils Skajaa, MSc, and colleagues wrote. “Some studies, however, suggest that the decline in incidence is heterogeneous by age, with flat or increasing trends in younger adults.”

Skajaa, a PhD student in the department of clinical epidemiology at Aarhus University in Denmark, and colleagues examined nationwide trends in rates of stroke and related mortality among younger and older adults in Denmark between 2005 and 2018, looking at subtype, age, sex, severity and trends related to etiology. They used the Danish Stroke Registry and the Danish National Patient Registry to find patients aged 18 to 49 years (classified as younger adults) and patients aged 50 years and older (classified as older adults) who had experienced a first-time ischemic stroke, intracerebral hemorrhage or subarachnoid hemorrhage.

The researchers assessed age-standardized incidence rates as well as 30-day and 1-year mortality risk separately for younger and older adults. They also evaluated these measures according to smaller age groups, stroke subtype, sex and severity, using the Scandinavian Stroke Scale to assess severity. Skajaa and colleagues used average annual percentage changes (AAPC) to examine temporal trends.

The final analysis included 8,680 younger adults and 105,240 older adults who experienced an ischemic stroke or intracerebral hemorrhage.

Skajaa and colleagues found that the incidence rate per 100,000 person-years for ischemic stroke (20.8 in 2005 vs. 21.9 in 2018; AAPC, –0.6; 95% CI, –1.5 to 0.3) and intracerebral hemorrhage (2.2 in 2005 vs. 2.5 in 2018; AAPC, 0.6; 95% CI, –1 to 2.3) remained stable in younger adults. Among older adults, ischemic stroke and intracerebral hemorrhage incidence decreased, especially among patients aged 70 years or older. The incidence of subarachnoid hemorrhage also decreased, though more in younger adults.

Stroke mortality went down over time in both age groups, primarily because of declines in mortality following severe strokes. Specifically, 30-day and 1-year mortality due to subarachnoid hemorrhage “indicated declining trends for both younger and older adults,” Skajaa and colleagues wrote.

Study findings demonstrated that most trends were similar for men and women.

“Our study extends existing knowledge by examining trends in younger and older adults according to stroke severity,” the researchers wrote. “Mild ischemic strokes have increased in incidence, while the most severe cases have declined. In younger adults, the lack of an upward trend reported in some prior studies is encouraging, and further risk factor reduction could lead to a decline.”