Short summary

Perioperative bleeding is an important determinant of morbidity in cardiac surgery. AB0 blood group is correlated with the hemostatic balance. The relationship between blood group and venous thrombosis is well established. The relationship between blood group and bleeding in cardiac surgery is not well studied and the results are so far ambiguous. This study uses data on a large cardiac surgical cohort from a clinical database to test this relationship.

Rationale

Bleeding and hemostatic control are important aspects of cardiac surgery since bleeding and transfusion are important determinants of patient outcome. 

There is a well-established relationship between AB0-blood group and the plasma levels of vWF and facor VIII, where individuals with blood group 0 tend to have lower plasma levels of these important coagulation factors. This association is due a primary effect and the AB0-locus on plasma levels of vWF. The exact mechanism is still debated and could be linked to both synthesis and/or clearance of VWF from plasma. It is speculated that this is the mechanism behind the well-established relationship between AB0-blood group and thrombosis. In large population studies individuals with non-0 blood group has an almost 2 times increased risk for VTE. 

One could speculate that the flip side of a hemostatic balance with reduced thrombogenicity would be higher susceptibility to bleeding. Although this relationship is not as well established as the relation with thrombosis there have been several studies primarily in mucosal and gastrointestinal bleeding finding a correlation between ABO-group and bleeding. 

The specific relationship between blood group and bleeding is not well described. To my knowledge there are only two prior publications with ambiguous results.

Since there is a wide variance in the amount of perioperative bleeding and AB0 blood group is properly only one in many determinants of the amount of bleeding. A study on a large cohort will be needed to elucidate the relationship between blood group and blood loss. 

Description of the cohort

Patients who have undergone cardiac surgery on one of the centers in Aalborg, Aarhus, Varde or Odense during a 10 year period.

Data and biological material

Data on amount of postoperative drainage, type of surgery, time on extra corporal circulation, amount of fluids and transfusions and basic demographic were retrieved from the clinical database "Vestdansk Hjertedatabase." Data on blood group was retrieved from blood bank databases. 

Collaborating researchers and departments

Department of Clinical Immunology, Odense University Hospital

• Ulrik Sprogø

Department of Anesthesiology, Odense University Hospital

• Consultant, Claus Andersen