Study finds wide variability in use of blood transfusions for coronary artery bypass graft surgery

A study that includes data on more than 100,000 patients who underwent coronary artery bypass graft surgery finds that there is wide variability among hospitals in the U.S. on the use of blood transfusions, without a large difference in the rate of death, suggesting that many transfusions may be unnecessary, according to a study in the October 13 issue of JAMA. Another study in this issue of JAMA examines the effect of a restrictive transfusion strategy on outcomes after cardiac surgery.

"Patients who undergo cardiac surgery receive a significant proportion of the 14 million units of allogeneic [taken from a different individual] red blood cells (RBCs) transfused annually in the United States," the authors write. "Perioperative [around the time of surgery] blood transfusions are costly and have safety concerns. As a result, there have been multiple initiatives to reduce transfusion use. However, the degree to which perioperative transfusion rates vary among hospitals is unknown."

Elliott Bennett-Guerrero, M.D., of Duke University Medical Center, Durham, N.C., and colleagues conducted a study to assess the use of RBC, fresh-frozen plasma, and platelet transfusions in coronary artery bypass graft (CABG) surgery in current practice, and to determine the degree to which transfusion practices vary among U.S. hospitals. The study included 102,470 patients undergoing CABG surgery during 2008 at 798 sites in the United States.

The researchers found significant variability in the observed hospital-specific transfusion rates for all 3 blood products among the patients and hospitals included in the study. To ensure that between-center differences would not be dominated by random statistical variation, the researchers also analyzed the subset of hospitals performing at least 100 eligible on-pump CABG operations during the year. At these 408 sites (n = 82,446 cases), the frequency of blood transfusion rates ranged from 7.8 percent to 92.8 percent for RBCs, 0 percent to 97.5 percent for fresh-frozen plasma, and 0.4 percent to 90.4 percent for platelets.

"Multivariate analysis including data from all 798 sites (102,470 cases) revealed that after adjustment for patient-level risk factors, hospital transfusion rates varied by geographic location, academic status, and hospital volume. However, these 3 hospital characteristics combined only explained 11.1 percent of the variation in hospital risk-adjusted RBC usage," the authors write.

There was no significant association between hospital-specific RBC transfusion rates and all-cause mortality.

"As is the case in other areas of medicine, the degree of variability in clinical practice we observed represents a potential quality improvement opportunity. This is particularly complex in relation to transfusion practice in CABG surgery. The decision to transfuse has multiple triggers, resulting from a wide array of clinical scenarios and the consequent inability to apply standardized algorithms. The multiplicity of health care practitioners in CABG surgery care generates differences of opinion about safety and efficacy. Transfusion thresholds will change during the course of care; the threshold for a rapidly bleeding patient is different than for a stable patient postoperatively. Improvement in quality related to transfusion practice in CABG surgery is a multifactorial, complex but critically important, challenge," the researchers write.