The prevalence of stroke in community-dwelling individuals has remained stable in the US between 1999 and 2018, new figures have shown.
The data come from the National Health and Nutrition Examination Surveys (NHANES), a nationally representative database of the non-institutionalized civilian population of US adults aged 20 years and older.
Results show a small increase in stroke prevalence among men but in all other demographic groups (including those based on race, ethnicity, and age) overall stroke prevalence rates were stable.
“Our study shows a stable prevalence of stroke in community-dwelling individuals,” said senior author Andrea Schneider, MD, assistant professor of neurology at the University of Pennsylvania Perelman School of Medicine, Philadelphia. “This could be [a] reflection of more new cases alongside more people dying from their stroke or needing to live in an assisted care facility after their stroke; or it could be due to fewer new cases with better outcomes and survival.
“We cannot tell which scenario is happening from this data, but we hope it is the second one,” Schneider commented.
The results were presented by lead author Wells Andres, MD, a neurology resident at the University of Pennsylvania Perelman School of Medicine, Philadelphia, on April 24 at the American Academy of Neurology 2023 Annual Meeting in Boston, Massachusetts, and simultaneously published online in JAMA Neurology.
The authors explain that prevalence data reflect the number of people in the population who have suffered and survived a prior stroke. It thus represents the current burden of stroke and is important to inform public health interventions and guide resource allocation.
Schneider elaborated to theheart.org | Medscape Cardiology: “This study is looking at the prevalence of stroke, rather than the incidence. While the incidence of stroke shows the number of new stroke cases over time, prevalence takes into account anyone with a lifetime history of having had a stroke, so it includes new cases and older cases in patients who have survived.”
She noted that prevalence of a disease is affected by multiple factors, including incidence and mortality.
A decrease in stroke prevalence could be caused by a reduction in stroke incidence (fewer cases occurring) but it could also be caused by an increase in the number of people who have died as a result of their stroke, she explained.
This study looked at the prevalence of stroke in community-dwelling individuals, so the figures would also be affected by the number of people who have had a stroke and are not able to live in the community, she noted. So, a reduction in stroke prevalence in the community could also reflect an increase in more severe strokes resulting in people needing to live in nursing homes or assisted care facilities.
The current study reports both crude and age standardized prevalence estimates to account for changes in the age structure of the US population over the study period.
The data show a crude stroke prevalence of 2.8% and an age standardized stroke prevalence of 3.1%, which has remained stable from 1999 to 2018. The authors note that these figures are slightly higher than the 2006-2010 prevalence data from the Behavioral Risk Factor Surveillance System (BRFSS; 2.6%-2.7%).
Both prevalence estimates, that of the current NHANES data and the BRFSS, are higher than the 1973-1991 NHANES estimates, which showed that prevalence increased from 1.41% to 1.87%, they report.
“Taken together, although the burden of stroke increased from 1973 to 1991, it has stabilized in recent years,” they conclude.
The authors point out that stroke was self-reported in NHANES, which has high negative predictive value but modest positive predictive value.
Schneider highlighted that the NHANES data are representative of the whole US population of community-dwelling individuals, which she said was a “huge strength” of this study.
“Our estimates don’t reflect every person in the US because they don’t include individuals living in nursing homes or assisted care facilities,” she added. “But they give an idea of the number of people who are able to continue to live in the community after a stroke.”
She acknowledged, however, that it was not possible from these data to ascertain the reasons behind the stable prevalence figures.
“The key is that prevalence is a mix of many factors (incidence, mortality) and in our case, since we are looking at prevalence of stroke survivors living in the community, it also depends on stroke outcomes/stroke severity factors. Our study did not investigate what factors may be underlying the observed prevalence trends, but this is an area of ongoing research,” she said.
American Academy of Neurology 2023 Annual Meeting. Presented April 24.
JAMA Neurol. Published online April 24, 2023. Full text.
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