[THS] Many blood transfusions may increase risks

[Peter Webster]

http://www.guardian.co.uk/science/2008/apr/24/medicalresearch.health

Many blood transfusions may increase risks, doctors warn

· UK study found dangers for heart surgery patients
· Fears over death rate and storage lead to US inquiry
Ian Sample, science correspondent
The Guardian,
Thursday April 24 2008

More than half of blood transfusions may do more harm than good,
with some patients facing a six-fold greater risk of dying following
surgery because of transfusions, doctors warn today.

Fears over the safety of blood transfusions have prompted some
physicians to recommend they are used only as a last resort, with
hospitals urged to be more selective over which patients receive blood.
According to a report in New Scientist today, the National Institutes of
Health, the US government's largest medical funder, has launched a
review into the safety of the procedure. Bruce Spiess, a cardiac
anaesthetist at Virginia Commonwealth University in Richmond, America,
told the magazine: "Probably 40%-60% of blood transfusions are not
good for the patients."

While the risks of contracting life-threatening infections, such as HIV,
from blood transfusions are well understood, doctors believe the danger
posed by the blood itself is more serious.

Although they do not fully understand why blood transfusions are linked
to higher death rates, they suspect that ageing blood that has been
stored before being given to patients is less able to carry oxygen to vital
organs and causes damage to the immune system.

Blood transfusions became a common procedure during the two world
wars, when they were used to save critically-injured soldiers. They are
now used routinely in heart surgery, hip replacement operations and
cancer treatment. According to the National Blood Service, only 8% of
donated blood is used in accident and emergency situations.

According to New Scientist, a recent flurry of studies highlighting the
risks of blood transfusions has prompted the wide-ranging safety
review. One study of almost 9,000 patients, led by cardiac surgeon
Gavin Murphy at the Bristol Heart Institute, found that patients who had
heart surgery between 1996 and 2003 were three times more likely to
die a year after their operation if they had a blood transfusion. In the
month after surgery they were six times more likely to die than patients
who did not receive donated blood.

"There is virtually no high-quality study in surgery, or intensive care or
acute care, outside of when you are bleeding to death, that shows that
blood transfusion is beneficial, and many that show it is bad for you,"
he said. There are more than 30,000 cardiac operations in Britain each
year, with around half involving blood transfusions.

The American review will attempt to find out why blood transfusions
appear to be so harmful to many patients.

One theory is that chemicals in donated blood suppress the patient's
immune system, making it harder to fight off infections. But doctors also
know that within hours of being collected red blood cells stiffen up,
making them less able to squeeze down narrow blood vessels and
supply oxygen to vital organs.

A study published last month in the New England Journal of Medicine
found that patients who received blood that was more than two weeks
old were almost 70% more likely to die within a year than patients who
received fresher blood.

John Wallwork, professor of cardiothoracic surgery at Papworth hospital
in Cambridge, said: "We are concerned about blood transfusions for a
variety of reasons. We don't want to use blood unless we have to. In
heart surgery around half receive blood transfusions, but often they are
patients who are sicker or bleed significantly during the operation. It's
always a case of balancing the risks."