ABO Blood Group and Risk of Vascular Events

Study Questions:

What is the association between ABO blood group and the incidence of venous thromboembolism (VTE) and arterial vascular events?


Using the SCANDAT2 database of blood donors and nationwide health data registries from Scandinavian countries, all blood donors in Denmark and Sweden between 1987 and 2012 were followed for a diagnosis of VTE or arterial vascular events. Patients with a prior history of VTE or cardiovascular disease were excluded. Poisson regression models were used to calculate incidence rate ratios (IRRs) for first and recurrent VTE as well as arterial events. The population-attributable risk percentage of thromboembolic events was calculated.


Among 1,112,072 blood donors without prior VTE or cardiovascular disease, 9,170 VTE events and 24,653 arterial events were identified over 13.6 million person-years of follow-up. As compared to blood group O patients (n = 446,120), non-O blood group patients (n = 665,952) experienced a higher incidence of VTE (IRR, 1.80; 95% confidence interval [CI], 1.71-1.88) and arterial events (IRR, 1.10; 95% CI, 1.05-1.14 for myocardial infarction and IRR, 1.07; 95% CI, 1.02-1.12 for stroke). The highest IRRs were observed in pregnancy-related VTE (IRR, 2.22; 95% CI, 1.77-2.79), deep vein thrombosis (IRR, 1.92; 95% CI, 1.80-2.05), and pulmonary embolism (IRR, 1.80; 95% CI, 1.71-1.88). The population-attributable risk percentage conferred by non-O blood groups ranged from 24-42% for various VTE diagnoses.


The authors concluded that non-O blood type patients are at higher risk for VTE as compared to O blood type patients, explaining up to 42% of VTE diagnosis variation.


Beyond its use to determine blood transfusion and organ transplantation compatibility, ABO blood type has been associated with VTE and arterial thrombotic event risk. This is usually attributed to higher concentration of factor VIII and von Willebrand factor in non-O type patients. This analysis confirms prior work using a large, multinational data set to estimate the potential risk associated with non-O blood group and thromboembolic event risk (primarily VTE). However, implications in clinical practice, including if ABO blood group should be used to screen for VTE risk or make treatment decisions following an incident VTE diagnosis, remains unclear and requires further investigation.

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