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Stroke rates among COVID-19 patients are low, but cases are more severe

May 21, 2020

DALLAS, May 21, 2020 -- The rate of strokes in COVID-19 patients appears relatively low, but a higher proportion of those strokes are presenting in younger people and are often more severe compared to strokes in people who do not have the novel coronavirus, while globally rates for stroke hospitalizations and treatments are significantly lower than for the first part of 2019, according to four separate research papers published this week in Stroke, a journal of the American Stroke Association, a division of the American Heart Association.

In "SARS2-CoV-2 and Stroke in a New York Healthcare System," researchers reported key demographic and clinical characteristics of patients who developed ischemic stroke associated with the COVID-19 infection and received care within one hospital system serving all 5 boroughs of New York City.

During the study period of March 15 through April 19, 2020, out of 3,556 hospitalized patients with diagnosis of COVID-19 infection, 32 patients (0.9%) had imaging-proven ischemic stroke. They compared those 32 patients admitted with stroke and COVID-19 to those admitted only with stroke (46 patients) and found that the patients with COVID-19:
  • tended to be younger, average age of 63 years vs. 70 years for non-COVID stroke patients;
  • had more severe strokes, average score of 19 vs. 8 on the National Institutes of Health Stroke Scale;
  • had higher D-dimer levels, 10,000 vs. 525, which can indicate significant blood clotting;
  • were more likely to be treated with blood thinners, 75% vs. 23.9%;
  • were more likely to have a cryptogenic stroke in which the cause is unknown, 65.6% vs. 30.4%; and
  • were more likely to be dead at hospital discharge, 63.6% vs. 9.3%.
Conversely, COVID-19 stroke patients were less likely than those stroke patients without the novel coronavirus to have high blood pressure (56.3% vs. 76.1%) or to have a prior history of stroke (3.1% vs. 13%).

The researchers observed that the rate of imaging-confirmed acute ischemic stroke in hospitalized patients with COVID-19 in their New York City hospital system was lower compared to prior reports in COVID-19 studies from China. One reason for the difference might be related to variations in race/ethnicity between the two study populations. In addition, the low rate of ischemic stroke with COVID-19 infection may be an underestimate because "the diagnosis of ischemic stroke can be challenging in those critically ill with COVID-19 infection who are intubated and sedated," said lead study author Shadi Yaghi, M.D., FAHA, of the department of neurology at NYU Grossman School of Medicine in Manhattan.

Yaghi said, "It was difficult to determine the exact cause of the strokes of the COVID-19 patients, however, most patients appeared to experience abnormal blood clotting. Additional research is needed to determine if therapeutic anticoagulation for stroke is useful in patients with COVID-19." The researchers noted that at least one clinical trial is already underway to investigate the safety and efficacy of treatment for active clotting vs. preventive treatment in certain patients with COVID-19 infection presenting with possible clotting indicators.

Yaghi and his coauthors also noted the number of stroke cases with COVID-19 seems to have peaked and is now decreasing. This finding may be related to the overall reduction in COVID-19 hospital admissions, which may be due to social distancing and guidance for people to stay at home. In addition, the number of stroke patients hospitalized during the study period was significantly lower than the same time frame in 2019.

Similar trends are reported in several other studies also published this week in Stroke, reflecting a global disruption of emergency health care services including delayed care and a lower-than-usual volume of stroke emergencies during the COVID-19 pandemic crisis.

In a Hong Kong study, "Delays in Stroke Onset to Hospital Arrival Time during COVID-19," by lead author Kay Cheong Teo, M.B.B.S., researchers compared the stroke onset time to hospital arrival time for stroke and transient ischemic attack (TIA) patients from Jan. 23 to March 24, 2020 (the first 60 days from the first diagnosed COVID-19 case in Hong Kong) to the same time period in 2019. In 2020, 73 stroke patients presented to Queen Mary Hospital compared to 83 in 2019. However, the time from stroke onset-to-arrival time was about an hour longer in 2020 compared with last year (154 minutes vs. 95 minutes). In addition, the number of patients arriving within the critical 4.5-hour treatment window dropped from 72% in 2019 to 55% in 2020.

Also from China, "The impact of the COVID-19 epidemic on stroke care and potential solutions," by lead author Jing Zhao, M.D., Ph.D., detailed survey results from more than 200 stroke centers through the Big Data Observatory Platform for Stroke of China, which consists of 280 hospitals across China. They found that in February 2020, hospital admissions related to stroke dropped nearly 40%, while clot-busting treatment and mechanical clot-removal cases also decreased by 25%, compared to the same time period in 2019. The researchers cited several factors likely contributed to the reduced admissions and prehospital delays during the COVID-19 pandemic, such as lack of stroke knowledge and proper transportation. They also noted that another key factor was patients not coming to the hospital for fear of virus infection.

In a fourth study, "Mechanical Thrombectomy for Acute Ischemic Stroke Amid the COVID-19 Outbreak," by lead author Basile Kerleroux, M.D., researchers in France compared patient data from stroke centers across the country from February 15 through March 30, 2020 to data of patients treated during the same time period in 2019. They found a 21% decrease (844 in 2019 vs. 668 in 2020) in overall volume of ischemic patients receiving mechanical thrombectomy during the pandemic compared to the previous year.

Additionally, there was a significant increase in the amount of time from imaging to treatment overall -- 145 minutes in 2020 compared to 126 minutes in 2019, and that delay increased by nearly 30 minutes in patients transferred to other facilities for treatment after imaging. The researchers said delays may have been due to unprecedented stress on emergency medical system services, as well as primary care stroke centers lacking transfer resources needed to send eligible patients to thrombectomy capable stroke centers within the therapeutic window. They noted stricter applications of guidelines during the pandemic period could also have meant some patients may have not been referred or accepted for mechanical thrombectomy treatment during that time.
Co-authors and disclosures are noted in the four manuscripts.

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