Fourteen out of every 1,000 COVID-19 patients admitted to hospital experience a stroke, a rate that is even higher in older patients and those with severe infection and pre-existing vascular conditions, according to a report published this week.
COVID-19 has become a global pandemic, affecting millions of people worldwide. In many cases, the symptoms include fever, persistent dry cough, and breathing difficulties, and can lead to low blood oxygen. However, the infection can cause disease in other organs, including the brain, and in more severe cases can lead to stroke and brain hemorrhage.
A team of researchers at the Stroke Research Group, University of Cambridge, carried out a systematic review and meta-analysis of published research into the link between COVID-19 and stroke. This approach allows researchers to bring together existing - and often contradictory or under-powered - studies to provide more robust conclusions.
In total, the researchers analyzed 61 studies, covering more than 100,000 patients admitted to the hospital with COVID-19. The results of their study are published in the International Journal of Stroke.
The researchers found that stroke occurred in 14 out of every 1,000 cases. The most common manifestation was an acute ischemic stroke, which occurred in just over 12 out of every 1,000 cases. Brain hemorrhage was less common, occurring in 1.6 out of every 1,000 cases. Most patients had been admitted with COVID-19 symptoms, with a stroke occurring a few days later.
Age was a risk factor, with COVID-19 patients who developed stroke being on average (median) 4.8 years older than those who did not. COVID-19 patients who experienced a stroke were on average (median) six years younger than non-COVID-19 stroke patients. There was no sex difference and no significant difference in rates of smokers versus non-smokers.
Pre-existing conditions also increased the risk of stroke. Patients with high blood pressure were more likely to experience a stroke than patients with normal blood pressure, while both diabetes and coronary artery disease also increased risk. Patients who had more severe infection with SARSCoV2 - the coronavirus that causes COVID-19 - were also more likely to have a stroke.
The researchers found that COVID-19-associated strokes often followed a characteristic pattern, with stroke caused by blockage of a large cerebral artery, and brain imaging showing strokes in more than one cerebral arterial territory. They argue that this pattern suggests cerebral thrombosis and/or thromboembolism are important factors in causing stroke in COVID-19. COVID-19-associated strokes were also more severe and had high mortality.
