Stroke rates among COVID-19 patients are low, but cases are more severe
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, according to a study published in Stroke.
Shadi Yaghi, MD, NYU Langone Health, New York, and colleagues conducted a retrospective cohort study of consecutive patients with ischemic stroke who were hospitalized between March 15, 2020, and April 19, 2020, within a major health system in New York. The authors compared the clinical characteristics of stroke patients with a concurrent diagnosis of COVID-19 to stroke patients without COVID-19 (contemporary controls). In addition, patients were compared to a historical cohort of patients with ischemic stroke discharged from the hospital system between March 15, 2019, and April 15, 2019 (historical controls).
During the study period in 2020, out of 3,556 hospitalized patients with diagnosis of COVID-19 infection, 32 patients (0.9%) had imaging-proven ischemic stroke. Among these 32 patients, the median (interquartile range [IQR]) age was 62.5 (52.0–69.25) years and 23 (71.9%) were men.
The authors 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: median (IQR) in years: 63 (17) vs 70 (18), P=0.001;
- had more severe strokes based on the National Institutes of Health Stroke Scale (NIHSS): median (IQR) NIHSS score: 19 (23) vs 8 (12), P=0.007;
- had higher D-dimer levels: median (IQR) in ng/mL: >10,000 (7,427) vs 525 (2,871), P=0.011;
- were more likely to be treated with blood thinners: 75% vs 23.9%, P<0.001;
- were more likely to have a cryptogenic stroke in which the cause is unknown: 65.6% vs 30.4%, P=0.003; and
- had higher inpatient mortality: 63.6% vs 9.3%, P<0.001.
When compared with historical stroke controls (80 patients), patients with COVID-19 and stroke:
- were more likely to be men: 71.9% vs 45.0%, P=0.012;
- had higher admission NIHSS score: median (IQR) NIHSS score: 19 (23) vs 3 (12), P=0.001;
- had higher erythrocyte sedimentation rate level: median (IQR): 79 (53) vs 41 (52), P=0.001;
- were more likely to have positive troponin levels: 45.2% vs 8.1%, P<0.001;
- were more likely to have proximal large vessel occlusion: 45.5% vs 20.3%, P=0.026;
- were more likely to be treated with anticoagulation: 78.1% vs 25.0%, P<0.001;
- were more likely to have a cryptogenic stroke: 65.6% vs 25.0%, P<0.001; and
- had higher inpatient mortality: 63.6% vs 6.3%, P<0.001.
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 authors 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. They noted that the reason for the difference might be related to variations in race/ethnicity between the two study populations.
“In addition, the rate of ischemic stroke in our study may be an underestimate as the detection of ischemic stroke symptoms is challenging in those critically ill with COVID-19 infection who are intubated and sedated”, the authors wrote.
The lead author 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 authors noted that at least one clinical trial is already underway to investigate the safety and efficacy of treatment for active clotting versus preventive treatment in certain patients with COVID-19 infection presenting with possible clotting indicators.
The authors also said that 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”, they said.
The authors reported that the limitations of the research included the study being a relatively small, retrospective, observational study with potential for selection bias, absence of outcome data on all patients as some are still admitted receiving active clinical care. They added that complete laboratory investigations or diagnostic imaging were not available for all study subjects, and therefore, some cryptogenic strokes may be related to another undiagnosed mechanism. “This likely contributed to an increased prevalence of cryptogenic stroke subtype in patients with COVID-19 infection”, the authors noted.