JAMA: Less variability, use of blood transfusions could improve CABG outcomes

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Allogeneic blood transfusions during CABG are associated with increased morbidity and mortality rates, but variation in their use makes it difficult to implement improvements. Additionally, restricting transfusions reduces death and severe illness, according to two studies in the Oct. 13 issue of the Journal of the American Medical Association.

In the first study, Elliott Bennett-Guerrero, MD, of the Duke University Medical Center in Durham, N.C., and colleagues assessed 102,470 CABG operations at 798 sites during the calendar year of 2008 to review the use of allogeneic red blood cell (RBC), fresh-frozen plasma and platelet transfusions.

The rates of perioperative transfusion were 56.1 percent, 19.3 percent and 24.7 percent for packed RBCs, fresh-frozen plasma and platelet transfusions, respectively. More women received RBCs and transfusion rates varied by geographic locations as well.

Rates of the various transfusions varied at hospitals that perform at least 100 on-pump CABG operations: 7.8 to 92.8 percent for RBCs, 0 to 97.5 percent fresh-frozen plasma and 0.4 to 90.4 percent for platelet transfusions.

The cost of each RBC transfusion is estimated to range from $522 to $1,184. "Therefore, even an unnecessary transfusion is not deleterious, a reduction in the observed variability might result in significant cost savings," the authors wrote.

"Despite nearly two decades of awareness of inconsistent transfusion practices and the publication of clinical practice guidelines, there has been no improvement in disparate transfusion practices," they added.

While the degree of variability represents a potential quality improvement opportunity, the factors affected the variations are multiple and complex, according to Bennett-Guerrero and colleagues. They suggest a blood conservation program might be more effective than adhering to published guidelines. Also, there are no data from "large randomized trial of the safety and efficacy of blood transfusion in cardiac surgery."

In the second study, Ludhmila A. Hajjar, MD, PhD, from the University of Sao Paulo in Brazil, and colleagues found that using more stringent guidelines for the amount of blood transfused performed in patients undergoing cardiac surgery reduces the incidence of death and severe illness compared to patients who receive more transfusions.

From the TRACS (Transfusion Requirements After Cardiac Surgery) trial, they evaluated 502 patients who underwent cardiac surgery with cardiopulmonary bypass between February 2009 and February 2010 at a single center.

The patients were randomized to either a liberal strategy of blood transfusions to maintain hematocrit of 30 percent or greater (198 of 253 patients), or a restrictive strategy to maintain hematocrit that was equal to 24 percent or greater (118 of 249 patients).

There were no significant differences in the primary composite outcomes (death from any cause, cardiogenic shock, acute respiratory distress syndrome and acute renal injury requiring dialysis or hemofiltration during hospital stay) between the two groups: 10 versus 11 percent.

However, the amount of transfused red blood cell units were an independent risk factor for clinical complications or death at 30 days.

"The study is a notable addition to the existing body of evidence on the narrow benefits of red blood cell transfusion and its effect on outcomes in patients without hemorrhage," wrote Aryeh S. Shander, MD, from Englewood Hospital & Medical Center in Englewood, N.J., and Lawrence T. Goodnough, MD, from Stanford University School of Medicine in California, in an accompanying JAMA editorial.

"The trial by Hajjar et al showed that patients undergoing cardiac surgery who received fewer red blood cell transfusions did as well as those transfused more liberally, with no evidence of ischemia or impaired delivery of oxygen to tissues."