Today we will be discussing red blood cell transfusions in cardiac surgery patients. Several trials have shown that a restrictive approach to transfusion is a safe alternative to a liberal approach for most patients. However, these studies have not evaluated cardiac surgery patients who may benefit from increased oxygen carrying capacity.
Dr. Barnaby Reeves, who led the new trial, comments on current transfusion practices for cardiac surgery patients:
“Doctors make variable decisions about when to transfuse patients after cardiac surgery. Some doctors prefer to give a transfusion when a patient is only mildly anemic, believing that the transfusion will promote recovery, while other doctors prefer to wait to transfuse until a patient is substantially anemic. Most patients are not being given these transfusions for life-threatening bleeding.”
In order to determine whether a liberal or restrictive approach to transfusion is safe for cardiac surgery patients, more than 2000 patients from 17 hospitals in the United Kingdom were randomized. One-thousand patients were randomly assigned to receive restrictive transfusions only when their hemoglobin level dropped below 7.5 grams per deciliter. One-thousand three patients in the liberal-threshold group received transfusions when hemoglobin levels dropped below 9 grams per deciliter. The rates of transfusion were almost twice as high in the liberal group as compared to the restrictive group.
No significant differences between groups were observed when comparing serious complications such as heart attack, stroke, acute kidney injury, bowel infarction, or infections. For most other outcomes such as length of ICU stay and health care costs, no differences were observed. However, there was an increase in mortality of borderline statistical significance at three months in patients assigned to the restrictive group.
Dr. Reeves explains:
“We compared the proportion of patients who died in each group. The percentages here were 4.2% in the restrictive group and 2.6% in the liberal group. So these findings have prompted us to hypothesize that the liberal threshold, rather than the restrictive threshold as we originally thought, may be better for patients.”
The findings of increased mortality were supported by sensitivity analyses. Consequently, additional clinical trials on the safety of liberal versus restrictive transfusion approaches for cardiac surgery patients are needed.
We’ll be back with another edition of Transfusion News on April 15. Thanks for joining us.
References
1. Murphy GJ, Pike K, Rogers CA, Wordsworth S, Stokes EA, Angelini GD, Reeves BC, Investigators TI. Liberal or restrictive transfusion after cardiac surgery. N Engl J Med 2015;372: 997-1008.
2. Spertus J. “TITRe”ing the approach to transfusions after cardiac surgery. N Engl J Med 2015;372: 1069-70.
*The trial was funded by the National Institute for Health Research (NIHR) Health Technology Assessment program (ref: 06/402/94). The views and opinions expressed are those of the author and do not necessarily reflect those of the NIHR Health Technology Assessment program, the National Health Service or the Department of Health.
