Effects of Red Blood Cell Transfusion on Patients Undergoing Cardiac Surgery in Queensland—A Retrospective Cohort Study

Background Packed red blood cell (pRBC) transfusion is a relatively safe and mainstay treatment commonly used in cardiac surgical patients. However, there is limited evidence on clinical effects of transfusing blood nearing end-of shelf life that has undergone biochemical changes during storage. Objective To investigate evidence of associations between morbidity/mortality and transfusion of blood near end of shelf-life (>35 days) in cardiac surgical patients. Methods Data from the Queensland Health Admitted Patient Data Collection database 2007-2013 was retrospectively analysed. Coronary artery bypass graft and valvular repair patients were included. Multivariable logistic regression was used to examine the effect of pRBC age (<35 days vs ≥35 days) on in-hospital mortality and morbidity. As secondary analysis, outcomes associated with the number of pRBC units transfused (≤4 units vs ≥5 units) were also assessed. Results A total of 4514 cardiac surgery patients received pRBC transfusion. Of these, 292 (6.5%) received pRBCs ≥35 days. No difference in in-hospital mortality or frequency of complications was observed. Transfusion of ≥5 units of pRBCs compared to the ≤4 units was associated with higher rates of in-hospital mortality (5.6% vs 1.3%), acute renal failure (17.6% vs 8%), infection (10% vs 3.4%), and acute myocardial infarction (9.2% vs 4.3%). Infection carried an odds ratio of 1.37 between groups (CI=0.9-2.09; p=0.14) and stroke/neurological complications, 1.59 (CI=0.96-2.63; p=0.07). Conclusion In cardiac surgery patients, transfusion of pRBCs closer to end of shelf-life was not shown to be associated with significantly increased mortality or morbidity. Dose-dependent differences in adverse outcomes (particularly where units transfused were >4) were supported.