A new study has found that rates of subarachnoid haemorrhage have increased in older individuals and men in recent years, these rates have been disproportionately higher in Black people, compared to people of other races and ethnicities.
What is a subarachnoid haemorrhage stroke?
Subarachnoid haemorrhage is when bleeding occurs, with the cause usually being a burst blood vessel, in the area between the brain and the membrane that covers it.
The causes of this type of stroke can be a rupture of an aneurysm, high blood pressure or trauma.
In this study, researchers looked only at those not caused by trauma.
Study author, Fadar Oliver Otite says: “Subarachnoid haemorrhages unrelated to trauma account for 5% to 10% of all strokes in the United States, and are often deadly.
“Not only did we find an increase in these strokes over recent years, we also found the incidence was disproportionally higher and increasing in Black people while rates did not increase in people of other races and ethnicities.”
Methodology
Researchers reviewed state hospitalisations databases for New York and Florida and identified 39,475 individuals hospitalised for non-traumatic subarachnoid haemorrhage between 2007 and 2017.
Using Census data, they then calculated the annual rates of subarachnoid haemorrhage in those states and compared those rates over time for men, women, various age ranges, races and ethnicities.
Study Findings
It was discovered that over the 10-year study, the average incidence of subarachnoid haemorrhage for all participants was 11 cases per 100,000 individuals.
Rates were found to be high in women, with 13 cases per 100,000 individuals, compared to 10 cases per 100,000 for men.
It was also found that incidents also increased with age.
Middle-aged men had an average of 4 cases per 100,000 individuals, whilst men over 65, their average was 22.
Researchers discovered that incidence increased over time, 0.7 per cent a year on average overall.
Middle-aged men saw an increase at 1.1 per cent, older men at 2.3 per cent and older women at 0.7 per cent, however, incidence in young women declined by 0.7 per cent.
When the team switched their focus to race and ethnicity, they found that incidence was greater in Black people with an average of 15 cases per 100,000 compared to non-Hispanic white people with an average of 10 cases.
Also, incidence increased in Black people by 1.8 per cent per year, whilst rates for Hispanic, Asian and non-Hispanic white people did not change overtime.
Otite says: “The incidence of this type of stroke is disproportionately higher, and increasing, in Black people, leading to a widening of the racial incidence gap.
“Previous studies have found Black people develop high blood pressure younger and are more likely to have uncontrolled high blood pressure than non-Hispanic white people, so expanding efforts to control blood pressure may help reduce rates.
The causes also likely extend to socioeconomic factors including structural racism. Tackling racial disparities will require multifaceted interventions targeted at stroke risk factors and socioeconomic inequity.”
The study was limited by the fact researchers were unable to differentiate between strokes caused by aneurysms and those not caused by aneurysms, which would have been able to provide further insight.
