Effect of blood transfusion on long-term survival after cardiac operation

Background. Blood transfusions have been linked to increased morbidity and mortality. Bleeding during and after cardiac operations and the hemodilution effects of cardiopulmonary bypass commonly result in blood transfusions. Because we could not find any studies evaluating the effects of transfusion on long-term survival after cardiac operation, we sought to determine these effects. Methods. We studied 1,915 patients who underwent first-time isolated coronary artery bypass operations between July 6, 1994 and December 31, 1997 at our institution. Patients with transfusions were compared with those who had not been transfused. Long-term survival data were obtained from the United States Social Security Death Index. Groups were compared by Cox proportional hazard models, Kaplan-Meier survival plots, and hazard functions. Results. Six hundred forty-nine of 1,915 study patients (34%) received a transfusion during their hospitalization. Transfused patients were older, smaller, and more likely to be female, and had more comorbidity. Transfused patients also had twice the 5-year mortality (15% vs 7%) of nontransfused patients. After correction for comorbidities and other factors, transfusion was still associated with a 70% increase in mortality (risk ratio = 1.7; 95% confidence interval = 1.4 to 2.0; p = 0.001). By multivariate analysis, transfusion, peripheral vascular disease, chronic obstructive pulmonary disease, New York Heart Association functional class IV, and age were significant predictors of long-term mortality. Conclusions. We found that blood transfusions during or after coronary artery bypass operations were associated with increased long-term mortality.