A66-14 ABO Blood Group and Risk of Pulmonary Embolism: A Systematic Review and Meta-analysis

Rationale Pulmonary embolism (PE) remains a significant cause of illness and death among hospitalized and critically ill patients. The ABO blood group affects blood clotting tendencies through its influence on von Willebrand factor (vWF) and factor VIII levels. While non-O blood types have been linked to a higher risk of venous thromboembolism (VTE), the relationship with PE has not been clearly defined. This study reviewed available evidence to clarify that association. Methods PubMed, Embase, and Google Scholar were searched through January 2025 for observational cohort or case-control studies reporting PE events by ABO group. Two reviewers independently screened and extracted data. Pooled risk ratios (RR) comparing non-O (A, B, AB) with O blood groups were calculated using a random-effects model. Only human studies with clear diagnostic confirmation of PE were included, while reviews and single-case reports were excluded. Results Six studies published between 2009 and 2023, including about 35 000 participants, met the criteria. The incidence of confirmed PE ranged from 1.1 % to 3.6 % across studies. Combined results showed that non-O blood groups had a 1.4-fold higher risk of PE compared with group O (pooled RR 1.42; 95 % CI 1.20-1.66). Results were consistent across individual studies and remained significant after adjusting for age, sex, and conditions such as cancer or recent surgery. No single study dominated the pooled estimate, and excluding smaller cohorts did not change the direction of the findings. Conclusion Non-O blood groups are associated with about a 40 % greater likelihood of pulmonary embolism than group O. This association is biologically plausible since people with A, B, or AB blood types tend to have higher circulating vWF and factor VIII, which promote platelet adhesion and clot formation. Prospective studies examining ABO subtypes and detailed coagulation profiles may help identify patients who could benefit from more personalized prevention strategies to reduce the burden of pulmonary embolism. This abstract is funded by: none