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Blood group distribution and life-expectancy: a single-centre experience.

The antigens of the ABO blood group system (A, B and H determinants, respectively) are complex carbohydrate molecules on the extracellular surface of red blood cells1. However, besides being expressed on red blood cells, ABO antigens are also strongly expressed on the surface of a variety of human cells and tissues, including the epithelium, sensory neurones, platelets, and the vascular endothelium2. The clinical significance of the ABO blood group system does, therefore, extend beyond transfusion medicine as several reports have suggested an important involvement in the development of cardiovascular, oncological and other diseases3,4. In particular, a number of clinical studies and systematic reviews have documented a positive association between non-O blood type and the risk of developing both venous and arterial thrombotic events5–8. Although the underlying molecular mechanisms are not completely understood, ABO-related thrombosis is thought to be mediated by ABO carbohydrate modifications of von Willebrand factor (VWF) resulting in impaired proteolysis and higher levels of VWF, and consequently higher factor VIII plasma levels in individuals with a non-O blood type than in blood group O individuals9. 
 
Considering this association along with the finding that cardiovascular mortality is the first cause of death in men, it is not surprising that investigators have assessed whether ABO blood group correlates with life-expectancy10–12. However, as the investigations gave conflicting results, we decided to analyse such an association at our city hospital.