Stroke Incidence Trends Higher in Younger vs Older Adults

Trends in stroke incidence diverge by age in high-income countries, with the substantial decrease in incidence found at older ages not occurring at younger ages, new research shows.

“Clinicians shouldn’t dismiss young patients with stroke-like symptoms. We see many patients who have been told that ‘it sounded like a minor stroke, but you are too young’,” co-investigator Peter Rothwell, MD, PhD, Wolfson Centre for Prevention of Stroke and Dementia, University of Oxford, United Kingdom, told Medscape Medical News.

The findings were published online August 9 in JAMA Neurology.

‘Convincing’ Trend

In high-income countries, the overall incidence of stroke has declined 42% over the past four decades. However, stroke incidence for individuals younger than 55 years appears to be increasing in the United States and some other countries.

To investigate further, Rothwell and colleagues reviewed 26 published studies that reported age-specific stroke incidence across two or more periods.

The primary outcome was age-specific divergence in temporal stroke trends in individuals younger than 55 and those aged 55 or older.

Across studies, trends in absolute incidence stroke in younger adults were heterogeneous. However, all studies showed a less favorable trend in incidence at younger vs older ages (pooled relative temporal rate ratio, [RTTR], 1.57; 95% CI, 1.42-1.74).

This age-specific divergence was broadly similar by stroke subtype and gender. The overall RTTR was 1.62 for ischemic stroke (95% CI, 1.44-1.83), 1.32 for intracerebral hemorrhage (95% CI, 0.91-1.92), and 1.54 for subarachnoid hemorrhage (95% CI, 1.0-2.35). In addition, the RTTR was 1.46 and 1.41 for men and for women, respectively.

“In contrast to substantial falls in incidence of stroke at older ages in high-income countries, there have been convincing divergent temporal trends in stroke incidence at younger vs older ages thus far in the 21st century,” the investigators write.

“Although the focus over recent decades on prevention of vascular events at older ages in light of the aging population has clearly been successful, there is an urgent need to better understand the causes and routes to prevention of stroke at younger ages,” they add.

Similar Divergence

Rothwell noted that what is behind this rise in stroke incidence in younger age groups is unknown. “That is a ‘need more research’ issue,” he said.

The researchers write that although the age-specific divergence in stroke incidence “might seem surprising,” a similar divergence has been reported in high-income countries for other conditions that share risk factors with stroke.

This includes colorectal cancer, for which the increasing incidence only at younger ages has been attributed to age-specific trends in obesity, lack of exercise, and poor diet.

The investigators also note that there is a tendency for vascular risk factors to be undertreated at younger ages.

“When it comes to treating risk factors for stoke at young ages, the risk modeling approach will tend to lead to undertreatment of high risk patients because the models are based on predictors of stroke at older ages,” Rothwell said.

“We clearly need to avoid over-medication in early middle age, but we need better ways to identify those at high risk of stroke,” he added.

The research was funded by the National Institute for Health Research Oxford Biomedical Research Centre, Wellcome Trust, Masonic Charitable Foundation, and Wolfson Foundation. Rothwell reported no relevant financial relationships.

JAMA Neurology. Published online August 9, 2022. Abstract

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