Association of ABO-mismatched platelet transfusions with morbidity and mortality in cardiac surgery

BACKGROUND: The transfusion of ABO-mismatched platelets has been associated with increased morbidity and mortality during induction therapy for acute leukemia and allogeneic progenitor cell transplantation. STUDY DESIGN AND METHODS: Reported here is a cohort study of 153 patients u ndergoing primary coronary artery bypass graft or coronary valve replacemen t surgery by two surgeons in one institution during 1997 and 1998. All stat istics employed nonparametric two-sided tests (Mann-Whitney; Fisher's exact test). RESULTS: Patients receiving at least one ABO-mismatched: pool of platelets had a significantly longer hospital stay, more days of fever, greater total hospital charges, and more RBG transfusions. Mortality, hours in the inten sive care unit, days on antibiotics, and numbers of platelet transfusions w ere also greater in recipients of ABO-mismatched platelets, but these diffe rences were of less statistical significance. When the analysis was restric ted to the 139 patients who received no more than two pools of platelets, t he trends for increased morbidity and mortality (8.6% vs. 1.9%; p = 0.10) i n recipients of ABO-mismatched platelets persisted. The number of RBC trans fusions required in this latter cohort was 50 percent greater (mean, 6.1 vs . 9.2; p = 0.02), despite the fact that the number of platelet transfusions given was similar (mean, 1.2 vs. 1.3 pools; p = 0.22). CONCLUSIONS: ABO-mismatched platelet transfusions are associated with unfav orable outcomes in cardiac surgery, a relationship that remains unexplained . As this association has been found in three cohort studies in various cli nical settings, further investigation of this association is warranted.