Blood transfusions raise heart patients' infection and death risk -- especially women

December 19, 2006

ANN ARBOR, Mich. -- Blood transfusions save the lives of millions of heart surgery patients and others each year. But a new study suggests that patients who receive transfusions during heart bypass surgery have a higher risk of developing potentially dangerous infections, and dying, after their operation.

In fact, this increased risk may help explain a longstanding medical mystery: why women bypass patients are more likely than men to die in the first few months after surgery. Women are more likely to receive blood during heart bypass operations, which are performed on more than 465,000 Americans each year.

The findings, from the Patient Safety Enhancement Program (PSEP) at the University of Michigan Health System, are based on data from 9,218 Michigan bypass patients. After adjusting for factors such as the urgency of the operation, those who received blood transfusions from donors were five times more likely to die within 100 days of their operation than those who did not.

The paper is published in the December issue of the American Heart Journal. It builds on a previous U-M analysis that found that a difference in infection rates accounted for the difference in death risk between men and women bypass patients.

The U-M team, with the help of Neil Blumberg, M.D., of the University of Rochester Medical Center, focused on blood transfusions as a contributing factor. Prior research has shown that recipients of stored donor blood have more post-surgical infections, and that women receive more transfusions because they tend to have lower hemoglobin concentrations.

This new study connects the dots. "To the best of our knowledge, this is the first study to state that allogeneic transfusions may be the reason why women have a greater post-bypass surgery mortality risk than men," says author Mary A.M. Rogers, Ph.D., M.S., PSEP, research director and research assistant professor of internal medicine. Allogeneic is the term for blood from another person.

The authors strongly note that blood transfusions can be life-saving, and that the infections observed in this study are not likely due to contamination of the blood. Rather, they may be due to other factors, including the patient's immune response to substances such as white blood cells that are present in stored donor blood. These findings may help guide hospitals and blood banks in deciding whether to filter donated blood to reduce the levels of white blood cells. This practice is increasingly common, but not yet universal, in the United States.

The study is based on analysis of data from all Medicare beneficiaries ages 65 and older who had coronary artery bypass operations in Michigan in a single year.

The researchers performed statistical analyses that took into account the patients' blood transfusion status, their co-existing diseases, age, race, sex, and whether the bypass operation was done on an elective, urgent or emergency basis. They looked at infections and deaths that were reported during the 100 days after surgery.

In all, about 88 percent of women received an allogeneic blood transfusion during bypass surgery, compared with nearly 67 percent of men. When the researchers adjusted for other factors, women were 3.4 times as likely as men to receive blood. This gender difference was evident regardless of whether the operation was elective, urgent or emergency.

The odds of having an infection of any kind were about three times greater in patients who received allogeneic blood than in patients who did not. The more blood they received, the higher their infection risk. This "dose dependent" relationship strengthens the evidence that transfusions may be related to infections.

No single type of infection stood out as more common among blood recipients, which suggests a body-wide immune response issue rather than a problem, for example, at the site of the incision.

The analyses revealed that women were more likely to experience an infection than men after bypass surgery, which appeared to be due to the increased number of transfusions in women. This resulted in an increased mortality rate in women. Overall, 9 percent of women and 6 percent of the men died within 100 days of their operation.

For patients who had banked their own blood ahead of the operation and who received only their own blood, the infection risk was similar to that of patients who received no blood transfusions. Rogers notes that patients should ask their doctors regarding banking their own blood if possible, when scheduled for a bypass operation or other kind of surgery.

In addition, physicians are increasing their use of transfusion alternatives such as blood "expanders," blood substitutes and blood-conserving procedures during bypass surgeries.

The results also highlight the importance of the proper use of antibiotics and infection control practices in patients hospitalized for a surgical procedure, says Rogers.

The U-M team is investigating the issue further, including a new study funded by Blue Cross Blue Shield of Michigan Foundation to extend the research into elderly patients who recently underwent bypass surgeries in Michigan.
-end-
In addition to Rogers and Blumberg, the study authors included PSEP director Sanjay Saint, M.D., MPH; Catherine Kim, M.D., MPH; Brahmajee Nallamothu, M.D., MPH; and Kenneth Langa, M.D., Ph.D. It was funded by the Agency for Healthcare Research and Quality, the National Institutes of Health, the Department of Veterans Affairs, the John A. Hartford Foundation and a Paul B. Beeson Physician Faculty Scholars in Aging Research award.

Reference: American Heart Journal, Volume 152, Issue 6, Pages 1028-1034 (December 2006).

University of Michigan Health System

Related Immune Response Articles from Brightsurf:

Boosting chickens' own immune response could curb disease
Broiler chicken producers the world over are all too familiar with coccidiosis, a parasite-borne intestinal disease that stalls growth and winnows flocks.

Cells sacrifice themselves to boost immune response to viruses
Whether flu or coronavirus, it can take several days for the body to ramp up an effective response to a viral infection.

Children's immune response more effective against COVID-19
Children and adults exhibit distinct immune system responses to infection by the virus that causes COVID-19, a finding that helps explain why COVID-19 outcomes tend to be much worse in adults, researchers from Yale and Albert Einstein College of Medicine report Sept.

Which immune response could cause a vaccine against COVID-19?
Immune reactions caused by vaccination can help protect the organism, or sometimes may aggravate the condition.

Obesity may alter immune system response to COVID-19
Obesity may cause a hyperactive immune system response to COVID-19 infection that makes it difficult to fight off the virus, according to a new manuscript published in the Endocrine Society's journal, Endocrinology.

Immune response to Sars-Cov-2 following organ transplantation
Even patients with suppressed immune systems can achieve a strong immune response to Sars-Cov-2.

'Relaxed' T cells critical to immune response
Rice University researchers model the role of relaxation time as T cells bind to invaders or imposters, and how their ability to differentiate between the two triggers the body's immune system.

A novel mechanism that triggers a cellular immune response
Researchers at Baylor College of Medicine present comprehensive evidence that supports a novel trigger for a cell-mediated response and propose a mechanism for its action.

Platelets exacerbate immune response
Platelets not only play a key role in blood clotting, but can also significantly intensify inflammatory processes.

How to boost immune response to vaccines in older people
Identifying interventions that improve vaccine efficacy in older persons is vital to deliver healthy ageing for an ageing population.

Read More: Immune Response News and Immune Response Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.