The risk of stroke among older adults diagnosed with COVID-19 was highest within the first three days of diagnosis, according to preliminary research.

The analysis found that the greatest risk of stroke occurred during the first three days after COVID-19 diagnosis and was 10 times higher than during the control period -- 7 days before diagnosis or 28 days after diagnosis. Following the first three days after COVID-19 diagnosis, the stroke risk quickly declined, yet remained higher compared to the control period.

Further, those aged 65-74 years old, had a greater risk of stroke after COVID-19 diagnosis, compared to those ages 85 and older, and among those without a history of stroke. The findings will be presented at the upcoming American Stroke Association's International Stroke Conference 2022.

"Stroke following the diagnosis of COVID-19 is a possible complication of COVID-19 that patients and clinicians should be aware of," said Quanhe Yang, lead study author and senior scientist in the Division for Heart Disease and Stroke Prevention at the US Centers for Disease Control and Prevention (CDC) in Atlanta.

"Vaccination and other preventive measures for COVID-19 are important to reduce the risk of infection and complications including stroke," Yang added. Previous studies have examined the risk of stroke among adults with COVID-19; however, findings were inconsistent, and few focused specifically on older adults, who are at greater risk of stroke.

This study examined the risk of ischemic stroke, which is a stroke due to a blocked blood vessel, among older adults diagnosed COVID-19 by examining the health records of 37,379 people aged 65 and older. The patients were diagnosed with COVID-19 between April 1, 2020 through February 28, 2021 and were hospitalised for stroke from January 1, 2019 through February 28, 2021.

Specifically, between days 4-7 the stroke risk was 60 per cent higher, and between days 8-14, the stroke risk was 44 per cent higher compared to the control period. The lowest stroke risk occurred after 15-28 days when the risk of stroke was 9 per cent higher than during the control period.

"These findings can inform diagnosis, treatment and care of stroke among patients with COVID-19," Yang said. "Further studies are needed to clarify the age-dependent risk of stroke associated with COVID-19." Stroke is a major cause of long-term disability. Rapid treatment is critical to prevent brain damage or death, so it is important to recognise the warning signs of stroke and the correct action.