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• Posted February 3, 2022

Stroke Risk Highest for Older COVID Patients Soon After Diagnosis

Stroke is a possible complication of COVID-19, and researchers say they now know when that risk is highest.

A new study from the U.S. Centers for Disease Control and Prevention found the risk of COVID-related ischemic stroke appears greatest in the first three days after you're diagnosed with the virus. Not just higher, but 10 times greater than during the period before a person contracts COVID-19.

"The findings of our study, especially the substantial high risk of stroke during early days of COVID-19, are consistent with the findings of other studies," said study co-author Quanhe Yang, a senior scientist at the CDC.

"More and more evidence suggested that stroke following the diagnosis of COVID-19 is a possible complication of COVID-19 that patients and clinicians should understand. Vaccination and other preventive measures for COVID-19 are important to reduce the risk of infection and complications including stroke," Yang added.

Stroke is the fifth leading cause of death in the United States. Ischemic stroke, caused by a blocked blood vessel, is the most common type.

While previous studies have been inconsistent in their findings on stroke risk among adults with COVID-19, few have focused on older adults, who tend to have a greater risk of stroke.

For this study, the researchers used the health records of more than 37,300 U.S. Medicare beneficiaries aged 65 and older. They had been diagnosed with COVID-19 between April 1, 2020, and February 28, 2021, before most people had an opportunity to be vaccinated.

The data included patients hospitalized for stroke prior to the pandemic in 2019 through February 2021. Yang's team compared stroke risk in the days just before and after the COVID-19 diagnosis to the risk during the other days of the study -- that is, seven days before COVID diagnosis to 28 days after diagnosis.

That 10-times higher risk of the first three days quickly declined. At four to seven days, the risk was 60% higher than in the control period, and by days eight to 14, it was down to 44% higher. At 15 to 28 days after diagnosis, it was only 9% higher, the researchers reported.

"This provides a little bit of reassurance that early risk does decrease over time," said Dr. Louise McCullough, chair of neurology at UT Health Houston and chief of neurology at Memorial Hermann Hospital in Houston.

The risk of stroke was higher for a younger subset of the people in this study, those aged 65 to 74, compared to those 85 and older. More research is needed to understand why that was so.

Bacterial and viral infections from flu to shingles can temporarily boost a person's risk of stroke shortly after exposure, Yang said.

The heightened risk associated with infection in general is likely due to inflammation, which may cause an increased risk of clotting or thrombosis, said McCullough, who was not involved in the study.

"We've known this in infections for quite some time. The question is, is there a disproportionate risk due to COVID or is this just because these patients are very sick and in the hospital?" McCullough said.

The stroke risk may decline after those initial days because the patients' infections are becoming under control, they're receiving fluids and they're getting steroids that decrease the inflammatory response, McCullough suggested.

The findings will be presented at the American Stroke Association's annual conference, held in New Orleans and virtually, Feb. 8 to Feb. 11.

Even early on, "many of us heard about or experienced having young patients without risk factors at home with COVID and experiencing really terrible events like bad ischemic strokes," said Dr. Marc Bonaca, chair of the American College of Cardiology's peripheral vascular disease council.

The study results remind patients and clinicians alike to treat risk factors like high cholesterol and high blood pressure, because if you are taking therapies that reduce stroke risk overall, that will reduce your risk if you do get COVID-19, said Bonaca, a professor of medicine and cardiology at the University of Colorado in Aurora.

"Having people's blood pressure well-controlled, having people on statins and cholesterol-lowering medications and so on. I think this is a good reminder that we should be doing everything we can," Bonaca said, adding healthy lifestyles are key as well.

"The 10-fold risk is based on your baseline risk, but if you can lower your baseline risk, your overall risk is lower," Bonaca said. He played no role in the research.

Yang said when the data becomes available, the researchers intend to follow up with a similar study that includes information on vaccination status and COVID variants, such as Omicron and Delta.

Data and conclusions presented at meetings should be considered preliminary until published in a peer-reviewed medical journal.

More information

The U.S. Department of Health and Human Services has more on reducing risk of stroke.

SOURCES: Quanhe Yang, PhD, senior scientist, epidemiology and surveillance branch, division for heart disease and stroke prevention, U.S. Centers for Disease Control and Prevention, Atlanta; Louise McCullough, MD, PhD, chair of neurology, UT Health Houston and chief of neurology, Memorial Hermann Hospital, Houston; Marc Bonaca, MD, MPH, chair, American College of Cardiology's Peripheral Vascular Disease Council, professor of medicine and cardiology, and director, vascular research, University of Colorado, Aurora; American Stroke Association International Stroke Conference, Feb. 8 to 11, 2022