from theheart.org
São Paulo, Brazil and Durham NC - More evidence that blood transfusions are being used too liberally in cardiac-surgery patients has come from two new studies, both published in the October 13, 2010, issue of the Journal of the American Medical Association.
One study, conducted in Brazil, found no difference in outcomes between two transfusion strategies, one more conservative than the other. The second study, by a group from Duke University, showed an "enormous" variation in transfusion rates in CABG patients across US hospitals.In an accompanying editorial, Dr Aryeh Shander (Englewood Hospital and Medical Center, NJ) and DrLawrence Goodnough (Stanford University School of Medicine, CA) say that continued inappropriate transfusions among hospitals is a major concern, as transfusions carry risks and are costly and the supply of blood is limited.
Goodnough told heartwire that the current Brazilian study echoed the results of an earlier study in ICU patients, and the Duke study showed similar variations in transfusion use as a study by his group in 1991. "We now have guidelines recommending a more conservative strategy, but these Duke data suggest that that they are not being taken notice of." He suggested two reasons for this: doctors are unaware of the guidelines, or they disagree with them. "I think there is a 'we've always done it that way' culture about giving blood transfusions, and once you have been taught something it can be difficult to let it go. But I believe there is enough data to say that we are overtransfusing."
In the Brazilian study, 502 cardiac-surgery patients were randomly assigned to a liberal strategy of blood transfusion (to maintain a hematocrit >30%) or to a restrictive strategy (to maintain a hematocrit >24%). Hemoglobin concentrations were maintained at a mean of 10.5 g/dL in the liberal-strategy group and 9.1 g/dL in the restrictive-strategy group. Blood transfusions were given to 78% of the liberal-strategy group and to 47% of the restrictive-strategy group, but occurrence of the primary end point (30-day all-cause mortality or cardiogenic shock, acute respiratory-distress syndrome, or acute renal injury requiring dialysis or hemofiltration during hospital stay) was similar between groups (10% liberal vs 11% restrictive).
In the second study, researchers led by Dr Elliott Bennett-Guerrero (Duke Clinical Research Institute, Durham, NC) analyzed data from the Society of Thoracic Surgeons (STS) adult cardiac-surgery database, which included 102 592 cases of CABG from 798 hospitals in 2008, and found a dramatic variability in the observed hospital-specific transfusion rates. To ensure that between-center differences would not be dominated by random statistical variation, they also analyzed the subset of hospitals performing at least 100 eligible on-pump CABG operations during the year. At these 408 sites, which included 82 446 cases, the frequency of transfusion rates ranged from 7.8% to 92.8% for red blood cells, 0% to 97.5% for fresh frozen plasma, and 0.4% to 90.4% for platelets. Geographic location, academic status, and hospital volume explained 11.1% of the variation in hospital risk-adjusted red blood cell usage, and case mix explained 20.1% of the variation.
Noting that they found no strong association between hospital transfusion rate and mortality, the authors note that even if higher transfusion rates at some hospitals are not deleterious, they may still represent potentially unnecessary care that is costly, with a red blood cell transfusion costing a mean of $761 per unit.
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