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New stroke risk score developed for COVID patients



Researchers have developed a quick and easy scoring system to predict which hospitalized COVID-19 patients are more at risk for stroke.

“The system is simple. You can calculate the points in 5 seconds and then predict the chances the patient will have a stroke,” Alexander E. Merkler, MD, assistant professor of neurology at Weill Cornell Medical College/NewYork-Presbyterian Hospital, and lead author of a study of the system, told this news organization.

The new system will allow clinicians to stratify patients and lead to closer monitoring of those at highest risk for stroke, said Dr. Merkler.

The study was presented during the International Stroke Conference, presented by the American Stroke Association, a division of the American Heart Association.

Some, but not all, studies suggest COVID-19 increases the risk of stroke and worsens stroke outcomes, and the association isn’t clear, investigators note.

Researchers used the American Heart Association Get With the Guidelines COVID-19 cardiovascular disease registry for this analysis. They evaluated 21,420 adult patients (mean age 61 years, 54% men), who were hospitalized with COVID-19 at 122 centers from March 2020 to March 2021.

Investigators tapped into the vast amounts of data in this registry on different variables, including demographics, comorbidities, and lab values.

The outcome was a cerebrovascular event, defined as any ischemic or hemorrhagic stroke, transient ischemic attack (TIA), or cerebral vein thrombosis. Of the total hospitalized COVID-19 population, 312 (1.5%) had a cerebrovascular event.

Researchers first used standard statistical models to determine which risk factors are most associated with the development of stroke. They identified six such factors:

  • history of stroke
  • no fever at the time of hospital admission
  • no history of pulmonary disease
  • high white blood cell count
  • history of hypertension
  • high systolic blood pressure at the time of hospital admission

That the list of risk factors included absence of fever and no history of pulmonary disease was somewhat surprising, said Dr. Merkler, but there may be possible explanations, he added.

A high fever is an inflammatory response, and perhaps patients who aren’t responding appropriately “could be sicker in general and have a poor immune system, and thereby be at increased risk for stroke,” said Dr. Merkler.

In the case of pulmonary disease, patients without a history who are admitted for COVID “may have an extremely high burden of COVID, or are extremely sick, and that’s why they’re at higher risk for stroke.”

The scoring system assigns points for each variable, with more points conferring a higher risk of stroke. For example, someone who has 0-1 points has 0.2% risk of having a stroke, and someone with 4-6 points has 2% to 3% risk, said Dr. Merkler.

“So, we’re talking about a 10- to 15-fold increased risk of having a stroke with 4 to 6 versus 0 to 1 variables.”

The accuracy of the risk stratification score (C-statistic of 0.66; 95% confidence interval, 0.60-0.72) is “fairly good or modestly good,” said Dr. Merkler.

A patient with a score of 5 or 6 may need more vigilant monitoring to make sure symptoms are caught early and therapies such as thrombolytics and thrombectomy are readily available, he added.

Researchers also used a sophisticated machine-learning approach where a computer takes all the variables and identifies the best algorithm to predict stroke.

“The machine-learning algorithm was basically just as good as our standard model; it was almost identical,” said Dr. Merkler.

Outside of COVID, other scoring systems are used to predict stroke. For example, the ABCD2 score uses various factors to predict risk of recurrent stroke.

Philip B. Gorelick, MD, adjunct professor, Northwestern University Feinberg School of Medicine, Chicago, said the results are promising, as they may lead to identifying modifiable factors to prevent stroke.

Dr. Gorelick noted that the authors identified risk factors to predict risk of stroke “after an extensive analysis of baseline factors that included an internal validation process.”

The finding that no fever and no history of pulmonary disease were included in those risk factors was “unexpected,” said Dr. Gorelick, who is also medical director of the Hauenstein Neuroscience Center in Grand Rapids, Michigan. “This may reflect the baseline timing of data collection.”

He added further validation of the results in other data sets “will be useful to determine the consistency of the predictive model and its potential value in general practice.”

Louise D. McCullough, MD, PhD, professor and chair of neurology, McGovern Medical School, The University of Texas Health Science Center, Houston, said the association between stroke risk and COVID exposure “has been very unclear.”

“Some people find a very strong association between stroke and COVID, some do not,” said Dr. McCullough, who served as the chair of the ISC 2022 meeting.

This new study looking at a risk stratification model for COVID patients was “very nicely done,” she added.

“They used the American Heart Association Get With The Guidelines COVID registry, which was an amazing feat that was done very quickly by the AHA to establish COVID reporting in the Get With The Guidelines data, allowing us to really look at other factors related to stroke that are in this unique database.”

The study received funding support from the American Stroke Association. Dr. Merkler has received funding from the American Heart Association and the Leon Levy Foundation. Dr. Gorelick was not involved in the study and has disclosed no relevant financial relationships.

A version of this article first appeared on

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