Association of ABO Blood Groups with Ischaemic Stroke Subtypes and Cerebrovascular Risk Factors Among Myanmar Patients: A Hospital-Based Cross-Sectional Study

Background: Ischaemic stroke is a leading cause of mortality and long-term disability worldwide. Genetic factors, including ABO blood group phenotypes, have been increasingly recognized as contributors to thrombotic and atherosclerotic vascular diseases. Non-O blood groups are associated with elevated levels of von Willebrand factor (vWF) and factor VIII, predisposing to thrombosis and large artery disease. However, evidence regarding the relationship between ABO blood groups and stroke subtypes remains limited in Southeast Asian populations. Objective: To evaluate the association between ABO blood groups, ischaemic stroke subtypes, and conventional cerebrovascular risk factors among Myanmar patients Methods: A hospital-based cross-sectional study was conducted among 255 patients with acute ischaemic stroke at No. (2) Military Hospital, Aung Ban, Myanmar, from January to December 2025. ABO blood grouping was determined serologically. Stroke subtypes were classified as cortical infarction (large artery atherosclerosis) and lacunar/posterior circulation infarction. Risk factors were recorded and analyzed using Chi-square test and odds ratios. Results: Blood group AB was most frequent (35.3%). Cortical infarction accounted for 70.6% of cases. Non-O blood groups were statistically significant with cortical infarction (77.8%, p<0.001). Hypertension (70.6%), smoking (56.9%), and hypercholesterolemia (47.1%) were highly prevalent and statistically significant with non-O blood groups ( p < 0.001).Blood group O was more common in lacunar/posterior circulation infarction. Conclusion: Non-O blood groups, especially AB, are significantly associated with large artery atherosclerotic stroke, while blood group O is more associated with small vessel disease. ABO blood group may serve as a genetic marker for cerebrovascular risk stratification.