COVID-19 Research: Harvard Study Shows That COVID-19 Patients With Blood Groups A And AB At Higher Risks Of Major Adverse Cardiovascular Events
: A new study by researchers from the Division of Cardiovascular Medicine, Department of Medicine, Harvard Medical School, Brigham and Women’s Hospital has found that blood groups are associated with cardiovascular events in COVID-19 patients. In particular blood groups A and AB were associated with higher risks of Major Adverse Cardiovascular Events (MACE).
From the study abstract, “Cardiovascular complications have been reported in patients with COVID-19. The study team sought to examine the association of ABO blood group type with cardiovascular complications in COVID-19. The team examined 409 individuals enrolled in the COVID-19 Registry to Assess Frequency, Management, and Outcomes of Arterial and Venous Thromboembolic Complications (CORONA-VTE) who had ABO blood group data available. Multiple logistic regressions were used to assess the association of ABO blood group types with three primary outcomes: major adverse cardiovascular events (MACE), major arterial and venous thrombosis and all-cause mortality. 201, 121, 61 and 26 individuals had blood group O, A, B and AB, respectively.”
“In multivariable analysis, blood group A was associated with a 2.5-fold higher odds of MACE than blood group O (OR 2.47[1.18–5.18]).
There was an effect suggesting a 2-fold higher risk of major thrombotic events in blood group A vs. O that did not reach statistical significance (OR 2.15 [0.89–5.20]). No association between blood group type and all-cause mortality was found. “
“Compared with the other blood group types, blood group A was associated with an increased odds of MACE (ORA/non−A 2.18[1.11–4.29]),
while blood group O was associated with lower odds of MACE(ORO/non−O 0.50[0.26–0.97]). “
“In conclusion, blood group A was associated with increased odds of MACE, whereas blood group O was associated with a reduction in the odds of MACE in patients with COVID-19.
These study findings may inform risk stratification of COVID-19 patients for cardiovascular complications. Additional studies are needed to validate the study findings.”
The study findings were published in the peer reviewed Journal of Thrombosis and Thrombolysis. https://link.springer.com/article/10.1007/s11239-020-02364-5
To date among the many complications that have emerged from coronavirus disease 2019 (COVID-19), cardiovascular events have become prominent.
The Harvard study team describes the correlation of such conditions with the ABO blood group. The study team's findings may help assess the risk of COVID-19 patients for such complications, promoting early diagnosis and underscoring potential needs for preventive and therapeutic care where possible.
The research took a retrospective observational cohort design. It included over 400 subjects enrolled in the COVID-19 Registry to Assess Frequency, Management, and Outcomes of Arterial and Venous Thromboembolic Complications (CORONA-VTE).
mp;rsquo; data came from electronic health records from hospitals in the Massachusetts General Brigham healthcare network. The subjects were followed up for 30 days, and the patient outcomes were assessed by a three-person panel.
The clinical outcomes examined were the conventional cardiovascular events; namely, major adverse cardiovascular events (MACE), major arterial and venous thrombosis, and all-cause mortality. MACE was a composite score including venous thromboembolism, myocardial infarction, ischemic stroke, transient ischemic attack, systemic embolism, major adverse limb events, heart failure hospitalization, new atrial fibrillation, and myocarditis.
Numerous variables were assessed for their potential effect on clinical outcomes.
These included age, race, sex, smoking status, body mass index, rhesus (Rh) status, pre-existing atherosclerosis, heart failure, atrial fibrillation, history of chronic anticoagulant or antiplatelet use, and statin therapy.
Blood group association with outcomes
Interestingly when classified by blood group, about half had blood group O, while about 30%, 15% and 6% had blood type A, B and AB, respectively. People who had a history of cerebrovascular events, who were non-Hispanic whites, or smokers, had a greater chance of having blood group A than O.
High blood pressure or hypertensive patients were less likely to have blood group B than O.
It was found that blood groups A and AB were associated with the highest incidence of all three major outcomes.
However, when other variables were adjusted for, the odds of MACE were 2.5 times more common in blood group A than blood group O. A strong trend was observed for an increased risk of major thrombosis in blood group A as well, at twice the frequency of blood group O, but this did not reach statistical significance. Again, mortality from all causes failed to show any relationship with the blood group.
When compared with all other blood groups, blood group A showed over twofold higher odds of MACE, and blood group O had only half the odds. Thus, blood group A had twice the odds of MACE.
Interestingly this adds to the findings of an earlier genome-wide association study that showed an association between the ABO locus and a higher chance of respiratory failure in COVID-19. https://www.nejm.org/doi/10.1056/NEJMoa2020283
In that recent study, it was shown that blood group A has a higher risk of respiratory failure in this infection, and blood group O a reduced risk.
This current study indicates that the ABO gene locus is associated with cardiovascular complications in patients with COVID-19.
Certain studies have shown that natural antibodies to glycan ABO antigens inhibit the SARS-CoV’s entry into the host cell, via the interaction between the viral spike glycoprotein and the angiotensin-converting enzyme 2 (ACE2) receptor. https://pubmed.ncbi.nlm.nih.gov/32437478/
Other blood groups besides O have also been found to associate with higher frequency of both arterial and venous clots, perhaps because they have higher levels of von Willebrand factor and factor VIII, both potent clotting factors. https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.115.017563
The researchers point out that this association cannot be taken to prove a causal role for the ABO blood group types in the pathogenesis of cardiovascular complications in COVID-19, and that further study is required.
The study team also calls for larger and more long-term studies to confirm these associations.
Importantly this new findings may help identify patients who are possibly at greater risk for these adverse outcomes, in order to provide optimal management and care.
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