Erythrocytes that have been stored for several weeks before use may not cause problems in patients who receive transfusions during noncardiac surgery, a large retrospective analysis suggests.
The study appears in Anesthesiology, in which the authors of an accompanying editorial - Jerrold Levy (Emory University School of Medicine, Atlanta, Georgia, USA) and Marie Steiner (University of Minnesota Medical School, Minneapolis, USA) - describe the research as an "important addition to the literature."
The study included 6994 patients who received transfusions during noncardiac study, so besides being large, the study involved patients who have not often been studied in this context - most previous similar studies involved cardiac or trauma patients. However, many previous studies also found that the risk for mortality and complications increased with use of older erythrocytes.
Patients in the current study received between one and 41 units of erythrocytes, and 24.6% died within 2 years of surgery. The researchers, led by Leif Saager (Cleveland Clinic, Ohio, USA), found no association between erythrocyte age as a continuous variable and postoperative mortality.
There was no evidence for a nonlinear or linear association, after accounting for confounders, with mortality at 1, 2, and 3 months, and 1 and 2 years postoperatively. In the linear model, there was a nonsignificant hazard ratio of 0.99 for mortality with each 1-week increase in erythrocyte age. There was also no association when patients were divided into groups according to the duration of erythrocyte storage: 3-14, 14.5-28, and 28.5-42 days.
Both the researchers and the editorialists observe that the findings appear to contradict those of a previous study from the same institution (Cleveland Clinic). However, this previous study was in cardiac patients, looked at a different time period, and only some of the erythrocytes were leukocyte-reduced, whereas all were in the study from Saager et al.
"These differences may contribute to the disparate results from the same center and indicate the caution necessary in interpreting the literature," say Levy and Steiner.
They conclude: "Whether the age of erythrocytes transfused has a significant effect on clinical outcomes still remains in a state of equipoise."
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