Patients hospitalised with Covid-19 may have a lower risk of stroke, according to a study that found majority of afflicted patients had existing risk factors, such as high blood pressure and diabetes.

The study, published in the journal Stroke, contradicts initial reports that suggested a significant risk of stroke in patients hospitalised with Covid-19.

“While there was initial concern for a high number of strokes related to Covid-19, that has not been born out,” said Brett Cucchiara, an associate professor at the University of Pennsylvania in the US.

“Importantly, while the risk for stroke in Covid-19 patients is low, it’s mostly tied to pre-existing conditions — so physicians who do see stroke in hospitalised Covid-19 patients must understand the virus is not the only factor, and it’s necessary to follow through with normal diagnostic testing,” Cucchiara said.

However, he said, there are still many unknowns and researchers need to continue investigating the linkage between stroke and Covid-19, particularly considering the racial disparities surrounding the disease.

To evaluate the risk and incidence of stroke in Covid-19 hospitalized patients, the researchers analyzed data from 844 Covid-19 patients admitted to the Hospital of the University of Pennsylvania, Penn Presbyterian Medical Center, and Pennsylvania Hospital, in the US, between March and May.

The team also analysed the data for cases of intracranial hemorrhage or bleeding in the brain.

Researchers found that 2.4 per cent of patients hospitalised for Covid-19 had an ischemic stroke — the most common type of stroke, typically caused by a blood clot in the brain.

They said the majority of these stroke patients had existing risk factors, such as high blood pressure (95 per cent) and a history of diabetes (60 per cent), and traditional stroke mechanisms, such as heart failure.

Also, over one-third had a history of a previous stroke, according to the researchers.

The results suggest that these cerebrovascular events in hospitalised Covid-19 patients are likely tied to existing conditions, and not the sole consequence of the virus, they said.

However, the researchers said, other factors could be at play and require continued research.

While the precise mechanisms linking cerebrovascular events to Covid-19 remain uncertain at this time, it has recently been reported that infection with Sars-CoV-2 causes inflammation and excessive blood clotting — both could be potential mechanisms leading to stroke, they said.