UCL News


COVID-19 linked to worse stroke outcomes

6 November 2020

People who experience strokes while infected with COVID-19 appear to be left with greater disability after the stroke, according a study led by UCL and UCLH researchers.

Features unique to COVID-19 may exacerbate psychological impact

Having COVID-19 at stroke onset was also associated with more than double the mortality rate of other stroke patients, according to the findings published in the Journal of Neurology Neurosurgery & Psychiatry.

The researchers found evidence that people of Asian descent might be more likely to experience COVID-19-associated ischaemic strokes (those caused by blockage of blood vessels supplying the brain) than those in other groups in the UK.

Lead researcher Dr Richard Perry (UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, UCLH) said: “By comparing characteristics and outcomes of strokes experienced by people with and without COVID-19, we found that there were differences between the groups, suggesting that COVID-19 exerts an influence over the presentation of stroke.

“Some of the differences relate to what other studies are uncovering about COVID-19, in that it might make blood stickier and more likely to clot.”

The findings build on previous studies led by UCL researchers which have also suggested that some people with COVID-19 are experiencing neurological symptoms, and that the infection may increase the risk of stroke.*

The researchers reviewed evidence from 86 people who had a stroke in England or Scotland and had COVID-19 at stroke onset, between March and July this year, and compared them to 1,384 stroke cases during the same period in people who did not have any evidence of COVID-19.

Evidence of infection was determined by a positive coronavirus test within four days of admission or suspected COVID-19 at the time of admission and confirmed on testing at any point during the subsequent 10 days.

The researchers found that ischaemic stroke patients who also had COVID-19 were only half as likely to leave hospital without any disability as those without COVID-19. The researchers do not yet have data on how long these excess disabilities might persist.

Ischaemic strokes in COVID-19 patients were around twice as likely to be caused by the blockage of more than one large blood vessel in the brain (18% vs 8%), which the researchers say suggests evidence of abnormal blood clotting. They also found that the COVID-19 associated strokes were more severe, with an average stroke severity (NIHSS) score of 8, compared to 5 in the control group.

Levels of D-dimers, a protein marker for the stickiness of blood, were also higher in COVID-19 related ischaemic stroke than in other ischaemic strokes. The new findings fit with other studies showing that people with COVID-19 appear to have sticky blood that is more liable to clot.

The researchers found differences by ethnicity, as people of Asian descent were overrepresented (by more than double) in the COVID-19 group than White or Black patients.

Dr Perry said: “Our study suggests that COVID-19 has had more impact on strokes in the Asian community than in other ethnic groups. We cannot say from our data whether this is because Asians are more likely to catch COVID-19, but it seems unlikely that this is the sole explanation. Evidence from Public Health England suggests that, in the UK, people of Afro-Caribbean origin are at the highest risk of catching COVID-19, while the risk for those of Asian descent appears to be lower, but still higher than it is for White people.** We suspect, therefore, that Asian individuals who contract COVID-19 may have a higher risk of COVID-19 associated stroke than is seen in other ethnic groups.”

Co-author Professor David Werring (UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, UCLH) added: “Our findings suggest that in some people, COVID-19 may influence stroke risk through its effect on excessive blood clotting or inflammation, and may also influence the characteristics and outcome of the stroke, including greater severity with a higher chance of multiple large vessel blood clots. 

“Our findings support testing people for COVID-19 if they come into hospital with a stroke, and further research is needed to determine whether treatments (such as the use of early full dose anticoagulation) should differ depending on this test result.”

The lead researchers were supported by the National Institute for Health Research UCLH Biomedical Research Centre. The study involved researchers at UCL and the universities of Manchester, Keele and Glasgow, as well as experts in hospitals in London, Manchester, Stoke-on-Trent, Newcastle, Birmingham, Southampton and Leeds.



  • Intensive care unit aboard the US hospital ship USNS Comfort. Credit: US Navy photo by Mass Communication Specialist 2nd Class Sara Eshleman. Source: Health.mil

Media contact

Chris Lane

Tel: +44 (0)20 7679 9222

Email: chris.lane [at] ucl.ac.uk