Story at a glance
- Stroke occurs when a person experiences rapid deterioration in neurological function.
- Symptoms of stroke include numbness or weakness on one side of the body and loss of language.
- Data suggests that a less common type of stroke is increasing in the U.S., especially among Black people.
Each year, about 795,000 people have a stroke in the U.S., according to the American Heart Association. About 87 percent are of one type of stroke: ischemic. New analysis suggests that another type may be on the rise, especially in Black populations.
A study published in the journal Neurology on Wednesday found that the incidence of stroke caused by subarachnoid hemorrhage (SAH), which accounts for 5 to 10 percent of strokes in the U.S. and can have a high fatality rate, rose by an average of 0.7 percent each year between 2007 and 2017 based on data from Florida and New York hospitals.
The study also found that while strokes cause by SAH occurred more commonly among women, its incidence increased over time among men, and that it was more common among Black people than those in other racial groups and increased over time among them as well.
Stroke of any type can be described as a sudden onset of neurologic deficits, says physician and study author Fadar Oliver Otite, who is a clinical assistant professor of neurology at the State University of New York Upstate Medical University in Syracuse.
SAH, specifically, occurs when blood gathers in the space that surrounds the brain. It can be caused by the rupture of an aneurysm, where a weak part of a blood vessel bulges outwards.
SAH has some overlap in symptoms with ischemic stroke, which is caused by a blockage in blood vessels to the brain, and a third type, intracerebral hemorrhage stroke, which results from bleeding within the brain tissue. Both of those types of stroke may commonly present with weakness or numbness on one side of the body or loss of language or speaking ability.
But with an SAH stroke, the biggest symptom is what Otite calls “the worst headache of your life.” This can also be called a thunderclap headache because of the speed at which it develops.
Out of nearly 40,000 hospital admissions, Otite and collaborators found that overall SAH increased by 0.7 percent each year on average over the course of the decade they looked at.
They found that SAH incidence was higher in women than in men, which aligns with past data. But the team also noticed that incidence in men increased over time, especially in men ages 45 to 64 years old and men 65 and over.
However, the team’s most striking findings may be the disparity they saw among racial groups.
Incidence of SAH in Black patients was found to have increased over time and to be about 1.5 times higher than in white people.
This type of stroke occurred in about 15 people per 100,000 people among Black patients, according to the study, compared to about 10 in white people and people who were identified as Hispanic. Incidence was lowest in Asian people, at 8 people per 100,000.
Black people were the only racial group where the team found incidence increased over time. In addition, differences in the rate of change between Black and non-Hispanic white populations suggested that the gap between the groups increased significantly over time.
The study additionally noted that the biggest risk factors for SAH were smoking and hypertension.
Otite emphasizes the need to inform patients about how smoking increases risk for SAH. Primary care physicians and neurologists can be more aggressive in trying to get their patients to quit smoking and to take care of their high blood pressure, he said. “We need to be more attentive to aggressive blood pressure control, particularly amongst Black patients,” Otite tells Changing America.
These findings highlight the need to disaggregate data and explore how health and disease present in different racial, ethnic and sex groups.
Black people are at higher risk of developing high blood pressure at a younger age. However, it’s also important to consider health within a larger context. “I truly feel that the higher incidence in Blacks go beyond just simple risk factor control,” says Otite. “It also extends to other factors like access to health care, access to education, poverty, and even structural racism.”
The study authors note that they were not able to further disaggregate data for people identified as Hispanic in this dataset. The team was also only able to see data for cases where people presented at a hospital for their symptoms, which could mean that only the most severe cases are accounted for. Lesser cases of SAH stroke could go undetected, or could later get worse and result in death but not get coded for SAH by health care practitioners. Additionally, they looked only at SAH that was not related to physical trauma like that resulting from accidents or falls.
Future studies to see what actions are taken to tackle this disparity would be interesting, says Otite. He noted studies will be needed to see how potential interventions could influence incidence over time.
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