ABO blood type and stroke risk: the REasons for Geographic And Racial Differences in Stroke Study.

Academic Article


  • BACKGROUND: ABO blood type is an inherited trait associated with coagulation factor levels and vascular outcomes. OBJECTIVES: To assess the association of blood type with stroke and whether blood type contributes to racial disparities in stroke in the United States. PATIENTS AND METHODS: The REasons for Geographic And Racial Differences in Stroke (REGARDS) Study recruited 30 239 participants between 2003 and 2007. Using a case-cohort design, blood type was genotyped in 646 participants with stroke and a 1104-participant cohort random sample. Cox models that adjusted for Framingham stroke risk factors were used to assess the association of blood type with stroke. RESULTS: During 5.8 years of follow-up, blood types A or B vs. type O were not associated with stroke. Blood type AB vs. O was associated with an increased risk of stroke (adjusted hazard ratio [HR] 1.83, 95% confidence interval [CI] 1.01-3.30). The association of blood type AB vs. O was greater in those without diabetes (adjusted HR 3.33, 95% CI 1.61-6.88) than those with diabetes (adjusted HR 0.49, 95% CI 0.17-1.44) (P interaction = 0.02). Factor VIII levels accounted for 60% (95% CI 11%-98%) of the association of AB blood type and stroke risk. CONCLUSION: Blood type AB is associated with an increased risk of stroke that is not attenuated by conventional stroke risk factors, and factor VIII levels were associated with 60% of the association. While blood type AB is rare in the US population, it is a significant stroke risk factor and may play an important role in stroke risk in these individuals.
  • Published In


  • ABO blood-group system, continental population groups, factor VIII, risk factors, stroke, ABO Blood-Group System, African Americans, Aged, Blood Coagulation Factors, Cohort Studies, Diabetes Complications, Ethnic Groups, European Continental Ancestry Group, Female, Follow-Up Studies, Geography, Haplotypes, Humans, Male, Middle Aged, Polymorphism, Single Nucleotide, Risk Factors, Stroke, Treatment Outcome, United States
  • Digital Object Identifier (doi)

    Author List

  • Zakai NA; Judd SE; Alexander K; McClure LA; Kissela BM; Howard G; Cushman M
  • Start Page

  • 564
  • End Page

  • 570
  • Volume

  • 12
  • Issue

  • 4