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Red blood cell transfusion appears safer than once believed: study

November 20, 2012 Toronto

Red blood cell (erythrocyte) transfusion is a common medical intervention, mainly in patients with life-threatening blood loss or severe anemia. But there is concern that receiving donated blood can affect the immune system and lead to adverse effects ranging from acute reactions to longer term effects including increased cancer risk and infections. A new study from the Institute for Clinical Evaluative Sciences (ICES) and University Health Network (UHN) suggests that red blood cell transfusion is safer than once thought.

There have been few randomized trials of transfusion, and non-randomized studies have consistently found increased mortality in patients who were transfused compared to those who were not. But the dilemma has been that patients who are transfused are usually sicker than those who are not. Consequently, it may be their underlying illness rather than the transfusion itself that leads to worse outcomes.

“Comparing outcomes of hospitals with differing transfusion rates may provide less biased estimates of risks of transfusion than comparing patients who did or did not receive transfusions,” says Dr. Keyvan Karkouti, lead author and associate professor of anesthesia at UHN, Toronto General Hospital. “Our study used this different methodological approach and found no excess deaths in patients who were transfused.”

The population-based cohort study examined patients who underwent elective hip- or knee-replacement surgery from 1999 to 2008 in Ontario. The study found that:

  • Of 162,190 patients, 23 per cent were transfused.
  • Compared to non-transfused patients, transfused patients experienced increased risk-adjusted 30-day and 1-year mortality.
  • Transfusion rates at the 66 study hospitals ranged from 10.3 to 57.9 per cent.
  • When hospitals were categorized according to their transfusion rates, risk-adjusted mortality rates across hospitals were very similar.

“The association of transfusion with postoperative mortality differed significantly when comparing transfused versus non-transfused patients, as opposed to comparing hospitals with differing transfusion rates. This discrepancy raises questions about the true relationship between transfusion and mortality,” says Dr. Duminda Wijeysundera, a research scientist at the Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, adjunct scientist at ICES, and assistant professor of anesthesia at Toronto General Hospital.

The study “Relationship of erythrocyte transfusion with short- and long-term mortality in a population-based surgical cohort” is in the December issue of Anesthesiology.

Author block: Keyvan Karkouti, Thérèse A. Stukel, William Scott Beattie, Susie Elsaadany, Ping Li, Rachel Berger, Duminda Wijeysundera.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

University Health Network consists of Toronto General and Toronto Western Hospitals, the Princess Margaret Cancer Centre, and Toronto Rehabilitation Institute. The scope of research and complexity of cases at University Health Network has made it a national and international source for discovery, education and patient care. It has the largest hospital-based research program in Canada, with major research in cardiology, transplantation, neurosciences, oncology, surgical innovation, infectious diseases, genomic medicine and rehabilitation medicine. University Health Network is a research hospital affiliated with the University of Toronto.  Visit Unvesrity Health Network website.

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