Trial results support restrictive approach to peri-operative blood transfusion
MedWire News: Restricting the use of red blood cell (RBC) transfusions in patients undergoing elective cardiac surgery does not increase peri-operative risk, the results of a randomized controlled trial suggest.
In the TRACS study, reported in the Journal of the American Medical Association, a strategy of transfusing patients only if their hematocrit fell below 24% was non-inferior to a more liberal strategy in which the trigger for transfusion was a hematocrit below 30%.
The TRACS (Transfusion Requirements After Cardiac Surgery) study was undertaken by Jean-Louis Vincent (Erasme University Hospital, Brussels, Belgium) and team. It was conducted at the Heart Institute of the University of Sao Paolo in Brazil, and enrolled 502 consecutive adult patients undergoing cardiopulmonary bypass surgery.
They were randomly assigned to either a liberal or a restrictive strategy of peri-operative RBC transfusion, aimed at maintaining hematocrit levels of at least 30% and 24%, respectively.
Overall, 78% of patients in the liberal group versus 47% of those in the restrictive group received a peri-operative blood transfusion (p<0.001); mean hematocrit values in the intensive care unit were 31.8% and 28.4%, respectively.
The trial's primary endpoint was a composite of 30-day death from any cause, cardiogenic shock, acute respiratory distress syndrome, or acute renal injury requiring dialysis or hemofiltration during hospitalization. This endpoint was met by 10% of patients in the liberal group and by 11% in the restrictive group, a nonsignificant difference (p=0.85).
In a multivariate analysis, factors that independently predicted the need for transfusion were previous cardiac surgery, female gender, duration of bypass, and baseline hemoglobin levels.
Furthermore, irrespective of transfusion strategy, the number of transfused RBC units was an independent risk factor for the occurrence of clinical complications, including mortality, at 30 days (p=0.002).
Noting that this is the first study to compare transfusion strategies in a rigorously controlled setting, the authors conclude: "The primary strategy in patients undergoing cardiac surgery should be to avoid giving RBC transfusion solely to correct low hemoglobin levels.
"The increased risk of mortality related to the number of transfused RBC units supports a restrictive strategy in cardiac surgery."
In an accompanying editorial, Aryeh Shander (Englewood Hospital, New Jersey, USA) and Lawrence Goodnough (Stanford University, California, USA) said the TRACS trial suggests that patients undergoing cardiac surgery who received fewer RBC transfusions fared as well as those transfused more liberally, with no evidence of ischemia or impaired delivery of oxygen to tissues.
They added: "When evaluating a hemoglobin level, treating physicians must resist the temptation to 'first do something' and temper this temptation with a philosophy of 'first do no harm' to achieve the optimal balance of providing the best risk-benefit and cost-effective outcomes of transfusion therapy for patients."
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By Joanna Lyford