ABO Blood Group and Clinical Outcomes in Acute Pulmonary Embolism: A Retrospective Cohort Study.

BACKGROUND: ABO blood group is a well-established determinant of venous thromboembolism risk, largely attributed to differences in circulating von Willebrand factor and factor VIII levels. However, its influence on disease severity and short-term outcomes in acute pulmonary embolism (PE) remains uncertain. METHODOLOGY: In this retrospective single-center cohort study, 317 consecutive adult patients hospitalized with a first episode of acute PE were included. ABO blood group was categorized as O versus non-O for the primary analysis. The primary outcome was in-hospital mortality. Secondary outcomes included Pulmonary Embolism Severity Index (PESI) score, thrombus localization on computed tomographic pulmonary angiography (CTPA), systemic thrombolysis, respiratory support requirement, infectious complications, sepsis, and ischemic stroke. Multivariable logistic regression was used to evaluate the independent association between ABO blood group and mortality, adjusting for age, sex, cancer history, and heart failure history. RESULTS: In-hospital mortality occurred in 35 patients (11.0%). Mortality was 14.5% in group O and 10.1% in non-O patients (crude OR 0.66, 95% CI 0.30-1.45; p=0.414). In adjusted analysis, non-O blood group was not independently associated with mortality (adjusted OR 0.67, 95% CI 0.30-1.49; p=0.324). Secondary analyses showed no consistent associations between ABO blood group and baseline severity markers, thrombus localization, or most in-hospital complications. CONCLUSIONS: In this cohort of patients with acute PE, ABO blood group was not independently associated with short-term mortality or clinically meaningful markers of disease severity, suggesting that ABO phenotype does not substantially influence prognostic stratification once pulmonary embolism is established.