A Randomized Clinical Trial of Red Blood Cell Transfusion Triggers in Cardiac Surgery

Colleen G. Koch, Daniel I. Sessler, Edward J. Mascha, Joseph F. Sabik, Liang Li, Andra I. Duncan, Nicole M. Zimmerman, Eugene H. Blackstone

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Background Class I evidence supporting a threshold for transfusion in the cardiac surgical setting is scarce. We randomly allocated patients to a transfusion hematocrit trigger of 24% versus 28% to compare morbidity, mortality, and resource use. Methods From March 2007 to August 2014, two centers randomly assigned 722 adults undergoing coronary artery bypass graft surgery or valve procedures to a 24% hematocrit trigger (n = 363, low group) or 28% trigger (n = 354, high group). One unit of red blood cells was transfused if the hematocrit fell below the designated threshold. The primary endpoint was a composite of postoperative morbidities and mortality. Treatment effect was primarily assessed using an average relative effect generalized estimating equation model. Results At the second planned interim analysis, the a priori futility boundary was crossed, and the study was stopped. There was no detected treatment effect on the composite outcome (average relative effect odds ratio, low versus high, 0.86, 95% confidence interval: 0.29 to 2.54, p = 0.71). However, the low group received fewer red blood cell transfusions than the high group (54% versus 75%, p < 0.001), mostly administered in the operating room (low group, 112 [31%]; high group, 208 [59%]), followed by intensive care unit (low, 105 [31%]; high, 115 [34%]) and floor (low, 41 [12%]; high, 42 [13%]). The low group was exposed to lower hematocrits: median before transfusion, 22% (Q1 = 21%, Q3 = 23%) versus 24% (Q1 = 22%, Q3 = 25%). Conclusions Negative exposures differed between treatment groups, with lower hematocrit in the 24% trigger group and more red blood cells used in the 28% group, but adverse outcomes did not differ. Because red blood cell use was less with a 24% trigger without adverse effects, our randomized trial results support aggressive blood conservation efforts in cardiac surgery.

Original languageEnglish (US)
Pages (from-to)1243-1250
Number of pages8
JournalAnnals of Thoracic Surgery
Issue number4
StatePublished - Oct 2017
Externally publishedYes

ASJC Scopus subject areas

  • Surgery
  • Pulmonary and Respiratory Medicine
  • Cardiology and Cardiovascular Medicine


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