Effect of duration of red blood cell storage on early and late mortality after coronary artery bypass grafting

Objectives: Recently, concern has been expressed about the transfusion of older red blood cells after cardiac surgery. We tested the hypothesis that longer storage of transfused red blood cells increases the risk of early and late mortality in patients who undergo coronary artery bypass grafting. Methods: We retrospectively analyzed data of patients who underwent isolated coronary artery bypass grafting between January 1998 and December 2007 in Catharina Hospital, Eindhoven, The Netherlands, and received up to 10 U of red blood cells intraoperatively or during the first 5 postoperative days. The patients were divided into 3 groups according to the storage time of the red blood cells, with a cutoff point of 14 days, as follows: "only younger blood" (n = 1422), "only older blood" (n = 1719), and at least 1 U of older RBCs ("any older blood"; n = 2175). Results: The mean follow-up time was 1693 ± 1058 days (range, 0-3708 days). The median follow-up time was 1629 days. Univariate and multivariate logistic regression analyses revealed that the number of transfused units but not the storage time of blood entered either as a continuous variable or as a dichotomous variable with a cutoff point of 14 days was a risk factor for early mortality. Neither the number of transfused units nor the storage time was an independent risk factor for late mortality. Log-rank testing revealed no statistical difference in survival among the groups. Conclusions: The storage time of transfused red blood cells is not a risk factor for early or late mortality in patients who undergo coronary artery bypass grafting.