U.S. blood centers have been operating under the assumption that 177 million
Americans could give blood. But that's a "gross overestimate," find
University of Minnesota researchers Jeffrey McCullough, MD, William Riley, PhD,
That 177 million figure overestimated the actual number of eligible U.S.
blood donors -- 111 million -- by 60%.
"The finding that blood donation rates are calculated with a 60%
overestimate is a tremendously important piece of scientific knowledge,"
McCullough tells WebMD. McCullough, professor of transfusion medicine,
laboratory medicine, and pathology and director of the biomedical engineering
institute at the University of Minnesota, serves as scientific director for the
St. Paul Regional Red Cross Blood Service.
There are 31 factors -- ranging from recent tattoos to HIV infection to
heart disease -- that either make a person's blood unsafe or make it unsafe for
a person to donate blood. Until now, estimates of the U.S. blood-donor pool
failed to take these factors into account.
"Ever since the dark days of the AIDS epidemic, blood safety has
skyrocketed. But if you look at all the factors you now screen for, nobody had
ever thought to add those up," McCullough says.
"The blood-donation community has been so focused on safety and the
challenge of securing safe blood, they haven't had the chance to look at the
biggest picture of all -- the actual number of eligible donors that are out
there," Riley tells WebMD. Riley is associate dean of health care finance
and management at the University of Minnesota School of Public Health.
Until now, blood-donation experts saw 60% of Americans as potential blood
donors. In reality, only 38% of Americans could give blood if they wanted
Blood Donation: Good News, Bad News
In one sense, the finding is good news for blood-collection centers. Instead
of getting only 81 units of blood per 1,000 eligible donors, they're actually
getting 129 units of blood per 1,000 donors.
On the other hand, the new findings mean that blood centers have pretty much
reached everybody they can with current efforts. They will have to come up with
new ways to motivate people to give blood, says Richard Benjamin, MD, PhD,
chief medical officer for the American Red Cross. Benjamin was not involved in
the McCullough study.
"We have for some years now been increasingly struggling to recruit
sufficient donors. This study really helps us understand why we are having that
struggle," Benjamin tells WebMD. "We need to devise new and innovative
ways of encouraging donors to give blood."
Or more blood. The average donor gives 1.7 times a year. Just increasing
this to two donations a year "would be a major step forward," Benjamin
McCullough and Riley say it's time to recruit sophisticated social
scientists to come up with ways to get more eligible donors to give blood.
"As the U.S. population ages and the demand for blood increases, if
blood banks don't come up with novel approaches, the blood supply will be in
real jeopardy," McCullough says.
Blood Safety Measures
Will blood banks relax their current safety standards so that fewer willing
donors will be turned away?
No, Benjamin says. But while he can't think of any current reason for donor
deferral that might be excessive, he says that blood centers will be thinking
twice before implementing new restrictions.
"It may be time for us to look more closely when we bring in new safety
measures that will defer broad swaths of donors who may not actually be at
risk," Benjamin says. "We have to ask, 'Can we afford to do
Benjamin also notes that safety cuts two ways.
"The most dangerous unit of blood is the one we don't have," he
says. "Not having blood for someone who needs it is worse than givin
someone a unit of blood that carries a 1-in-5 million chance of
But the real bottom-line message from the McCullough study is that eligible
blood donors are more important than ever before.
"If you are an eligible blood donor, you are now known to be a
minority," Benjamin says. "We strongly encourage eligible donors to
step forward and give blood on a regular basis. It is such a precious commodity
-- and it is getting harder and harder to get."
The study by Riley, McCullough, and colleagues appears in the July issue of
- Are you a blood donor? Why or why not? Talk with others on WebMD's Health
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By Daniel DeNoon
Reviewed by Louise Chang
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