A July 2020 study indicates that patients infected with COVID-19 are eight times more likely to have a stroke than patients sick with influenza, adding to the general consensus that the 2019-2020 coronavirus disease is far more serious than the yearly flu.
The study
Although both COVID-19 and the flu can trigger strokes, the risk appears to be much greater with the former, says Dr. Neal Parikh, assistant professor of neurology and neuroscience at Weill Cornell Medicine in New York City. Parikh and a team of researchers compared the likelihood of stroke among patients in two NYC hospitals infected with both the coronavirus and influenza. Health information from patients with COVID-19 was acquired from March 4, 2020, to May 2, 2020, and data from patients with the flu was taken from early 2016 to mid-2018.
The researchers found that among 1,916 patients hospitalized with the coronavirus, 31 of them had an acute ischemic stroke, the most common type of stroke. Among 1,486 patients with influenza, only 3 suffered a stroke.
“Doctors and practitioners taking care of patients with COVID-19 infection should remain vigilant for signs and symptoms of stroke, because prompt diagnosis may permit effective stroke treatment,” said Dr. Parikh. “Fundamentally, our results support the notion that COVID-19 infection is more severe than influenza infection.”
Theories for the link
Two established doctors – Dr. Larry Goldstein, professor and chairman of neurology at the University of Kentucky, and Dr. Salman Azhar, director of stroke at Lenox Hill Hospital in New York City – think that increased inflammation in the body, along with blood clotting, are responsible for COVID-19 causing strokes.
“Infections and other inflammatory conditions are established risk factors for stroke, so it is not surprising that patients with COVID-19 disease might have stroke as a complication of the infection,” said Dr. Goldstein, while Dr. Azhar stated: “This virus has a predilection to cause some level of clotting, and we think that maybe it’s because of increases in inflammation in the body.”
Blood clotting, coronavirus and stroke
Dr. Azhar says that the coronavirus attacks blood vessels in the body, raising an infected person’s risk for blood clots. Medical professionals, now aware that COVID-19 has been linked to blood clotting, have started putting hospitalized patients on blood thinners to prevent clots and reduce their risk of stroke. “Every patient with COVID-19 gets put on low-level blood thinners to try and prevent clots,” sad Azhar. According to Dr. Steven Schadendorf, a neurologist in California, some hospitals are testing all stroke patients for COVID-19 to make sure they are getting the treatment they need.
Is this cause for concern?
So does that mean you should be worried about this new coronavirus side effect? Well, the virus has certainly proven to be more deadly than the flu, but it’s important to note that having a stroke as a result of COVID-19 is extremely rare for anyone. And in the analysis done by Parikh and his team, the median patient age was 69, while the overwhelming majority of patients had cardiovascular risk factors, meaning that the chance that an average young, healthy person will have a stroke from COVID-19 is almost nonexistent.
Furthermore, a team of doctors at Thomas Jefferson University analyzed patients and, over the course of two months, found only 14 who had strokes. Of these patients, nine of them had underlying conditions. And a much larger study that examined 3,556 patients hospitalized with the coronavirus found that only 32 of them suffered from strokes, 25 of whom had underlying conditions. The majority were over 60.
