Transfusion practices among patients who did and did not predonate autologous blood before elective cardiac surgery.

Background: Preoperative autologous blood donation is commonly used to reduce exposure to allogeneic transfusions among patients undergoing elective cardiac surgery. However, this technique is associated with an overall increase in transfusions (allogeneic or autologous). The authors assessed the impact of transfusion decision-making on the effectiveness of preoperative autologous donation in reducing the frequency of allogeneic transfusions, and its impact on the increased transfusion rate associated with preoperative autologous donation in cardiac surgery.
Methods: This retrospective analysis compared transfusion practices among 176 patients who predonated autologous blood before elective cardiac surgery and 176 matched cardiac surgery patients who did not predonate blood. The impact of decision-making on transfusion exposure was determined using multivariate analyses to account for major perioperative interventions and complications. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for exposure to allogeneic blood transfusion or any transfusion, before and after exclusion of transfusions not conforming with selected transfusion criteria.
Results: Exposure to allogeneic transfusion was more likely among patients who did not predonate blood than among those who did predonate blood (OR 14.0, 95% CI 5.8-33.8). This finding was still true after exclusion of transfusions not meeting the transfusion criteria (OR 19.3, 95% CI 6.7-55.7). The autologous blood donors were more likely than the nondonors to receive any transfusion (OR 10.8, 95% CI 5.7-20.3). However, this association was substantially attenuated after exclusion of transfusions not meeting the transfusion criteria (OR 1.9, 95% CI 1.1-3.2).
Interpretation: Patients who predonated blood before elective cardiac surgery were at lower risk of receiving allogeneic transfusions than the nondonors. This was not because of a deliberate withholding of allogeneic transfusions from autologous donors. However, more liberal transfusion criteria for autologous blood were largely responsible for the increased transfusion rate among the autologous donors.