lood is a
good thing, but like many good things, it comes
with risks. In the USA, all emphasis is upon the
safety of the blood supply. During the past 3
decades, no less than 13 new tests on donor blood
have been mandated. The donors themselves have to
hurdle over some 50 questions before being
considered suitable to contribute blood and blood
products acceptable for transfusion.
Consequently, blood has become much safer but is
in increasingly shorter supply and very
expensive.
Like most efforts to
improve health care, the drive to improve safety
has sparked heated scientific and political
debates. While no one questions the goal of a
risk-free blood supply, the means by
which this is achieved often tracks through
difficult and tortuous routes that are not
necessarily in our nation's best interest. The US
blood safety vigilance system is composed of a
network of interwoven programs, now organized
under a formal structure, with the assistant
secretary of health and various committees
bearing overall responsibility. In essence, the
Food and Drug Administration (FDA) and Department
of Health and Human Services (HHS) oversee our
nation's blood supply. But while safety and
economics are intrinsically linked, the
government regards them as distinct entities and
places them under the supervision of 2 different
federal committees. While the FDA's Blood
Products Advisory Committee is confined to the
medical and scientific aspects of safe blood
procurement, the HHS's Advisory Committee on
Blood Safety and Availability examines the
economic, legal, and public health implications
of blood safety issues. Complications arise when
concerns over financial feasibility conflict with
consensus over safety. This conflict often
results in the formulation of unfunded mandates
and an inadequate reimbursement system that does
not recognize the true cost of blood (1).
Furthermore, this state of affairs is impacted by
the fact that the overseeing committees may not
have representatives from physician or hospital
groups or even from the blood banking industry.
Recently, 3
issues have impacted our nation's citizens and
the blood supply: hepatitis C virus (HCV)
look-back, universal leukoreduction (ULR), and
the bovine spongiform encephalitis (BSE) epidemic
in Western Europe, otherwise known as mad
cow disease.
Despite vigorous
medical objections, a targeted HCV look-back
program was mandated that applied only to the
recipients of potentially anti-HCV-positive
blood. As predicted, not only were donors and
recipients unnecessarily alarmed, but also the
public health rewards were minimal, if
nonexistent. The vast majority of recipients of
suspect blood transfusions either had
died of their initial disease process or tested
negative. Since it is well known that <10% of
all HCV infections could have been transfusion
acquired, would it not have been wiser to test
all individuals, if they so desired? However,
even though numerous studies have concluded that
the mandate was ineffective, both the FDA and the
HHS have proposed extending the HCV look-back to
include the findings of the now-obsolete
first-generation HCV 1.0 test (with its 70%
false-positive rate) and contacting the legal
representatives of deceased patients. Surely this
measure can only contribute further to the
spiraling cost of blood and benefit the legal
profession.
The issue of ULR
can be approached medically on a more rational
basis. A number of studies have shown that
transfused leukocytes are immunosuppressive, can
lead to severe febrile reactions, and can
initiate cytomegalovirus infection in individuals
with weakened immune systems. Also, transfused
leukocytes can cause alloimmunization and, on
rare occasions, mount a graft-vs-host disease
response in bone marrow transplant patients. For
these reasons and for some time now at Baylor
University Medical Center, the Transfusion
Service has issued leukoreduced packed red cells
and platelets to newborn infants, transplant
patients, and cancer patients on a rational
indication basis developed by the
Transfusion Committee.
In the USA, the
FDA has championed the cause for ULR and will
most likely mandate this measure in the very near
future. ULR is already carried out in Canada,
England, France, Norway, and Portugal. Hence,
with regards to ULR, the issue is cost and not
medical science. Its implementation will increase
the cost of a unit of blood by 25% to 30%. It
should be mentioned that approximately 3% to 5%
of units cannot be leukoreduced. This mandate
will serve to further exclude some valuable and
rare donors.
Since the HIV
epidemic, the possible but as yet unproven
transmission of new variant Creutzfeld-Jakob
disease (nvCJD) by transfusion in humans
represents yet another major threat to the safety
and availability of our blood supply. It has been
known for some time that several fatal diseases
are caused by modified prions, including scrapie
of sheep, bovine and feline spongiform
encephalitis, chronic wasting disease of deer and
elk, and CJD of humans. The latter condition
presents clinically with a rapidly dementing
illness associated with myoclonic jerks. The
average duration of the disease is 14 months but
can range from 7 to 38 months. The accumulation
of modified prion proteins in the central nervous
system causes fine spongiform change,
microvascularization, and consequent neuronal
loss and reactive gliosis. Characteristic
amyloid-rich plaques (so-called Kuru plaques) are
present, and immunostaining and blotting can aid
in the histologic diagnosis. In life, the
electroencephalogram may show triphasic waves
with frontodistal delay. Magnetic resonance
imaging of the brain and tonsillar biopsy are
considered reliable tests in the detection of
nvCJD in living patients when taken together with
other symptom-based criteria. As yet, no
diagnostic blood test has been developed for this
disease, although the observation of specific
binding of the malignant prion protein to
circulating plasminogen, recently reported by
Zurich scientists, could serve as the basis for a
diagnostic test for nvCJD (2). However, to date
there is no evidence in humans that nvCJD can be
transmitted by transfusion.
An outbreak of
BSE occurred in British cattle in the late 1980s
and early 1990. To contain the epidemic,
thousands of cattle were slaughtered. Also, some
younger individuals in Britain developed a new,
more aggressive type of CJD. This led British
scientists in 1996 to speculate that BSE had
jumped a species barrier and was responsible for
the nvCJD in humans. To date, almost 100 cases of
the human disease have been reported in Britain,
Ireland, and France. It was felt that the
transmission of the malignant prion in humans
occurred from eating infected beef, which itself
had been infected by tainted protein feed made
from the carcasses of sick animals. Hence, as a
precautionary measure in the USA, the FDA
recommended that blood donors who had visited the
United Kingdom between 1980 and 1996 for a
cumulative period of 6 months or more be
permanently deferred. Other countries such as
Australia implemented a similar ban. According to
Dr. Merlyn Sayers, chief executive officer of
Carter BloodCare, this stipulation alone has
resulted in the loss of >500 donors from our
community's blood program. Two recent published
reports will have significant repercussions for
blood banking as the FDA and HHS promulgate
future safety measures. Researchers in Scotland
have shown that it is possible to transmit BSE to
a sheep by transfusion with whole blood taken
from another sheep during the symptom-free phase
of an experimental BSE infection (3). Other
researchers in California were able to transmit
BSE from diseased cows to transgenic mice,
implying that the species barrier between these
mammals could be crossed (4).
It is clear that
blood and its components are not entirely safe
and probably never will be. However, they provide
a vital and indispensable therapeutic modality in
the practice of modern medicine. As new
infectious agents and diseases continue to be
reported, the risk-benefit analysis of blood
transfusion will require continual reevaluation.
The availability and safety of blood remain the 2
principal issues. Hence, what can we, as
physicians, do to assist with the forthcoming
blood shortage as the FDA and HHS implement new
safety regulations that can only further deplete
our national blood supply? Three measures can be
implemented immediately:
- Assist the local
blood center in all ways possible. Since
only 5% of eligible adults donate blood,
we should all become active recruiters.
Also, we should be mindful that our
community blood program can be strong
only to the extent that its mission is
endorsed by influential individuals, such
as physicians and hospital
administrators, who recognize the
importance of blood transfusion in
patient care.
- Implement the
strategy of type and screen
instead of type and cross
often and whenever feasible. This measure
alone serves to increase the shelf life
of packed red blood cells and reduces
wastage by 10%. Wastage can be further
diminished by not thawing fresh frozen
plasma and cryoprecipitate before they
are needed.
- Transfuse blood
and blood components only when these are
deemed necessary. Follow nationally
acceptable guidelines promulgated by
professional medical organizations (5,
6).
In 1999 blood
transfusion costs at Baylor University Medical
Center rose a whopping 25% over the previous
year. The American Hospital Association is asking
Congress to annually evaluate the real costs of
blood and blood component procurement.
Previously, this had been neglected. There should
be no disconnect between the FDA, the Advisory
Committee on Blood Safety and Availability, and
the Health Care Financing Administration, all of
which are part of HHS. The American Hospital
Association is asking that mechanisms be put in
place so that if one agency mandates a new
measure, the other agency pays for it.
Finally, I would
like to take this opportunity to thank Baylor
administrators and, in particular, Mr. Steve
Trowbridge for taking a major interest in the
problems unique to blood transfusion in the
Dallas-Fort Worth metroplex.
- Marengo-Rowe
AJ. Testimony on behalf of the American
Hospital Association to the US Department
of Health and Human Service Advisory
Committee on Blood Safety and
Availability. Washington, DC, April 26,
2000.
- Fischer
MB, Roeckl C, Parizek P, Schwarz HP,
Aguzzi A. Binding of disease-associated
prion protein to plasminogen. Nature
2000;408:479-483.
- Houston
F, Foster JD, Chong A, Hunter N, Bostock
CJ. Transmission of BSE by blood
transfusion in sheep. Lancet
2000;356:999-1000.
- Scott
MR, Will R, Ironside J, Nguyen HO,
Tremblay P, DeArmond SJ, Prusiner SB.
Compelling transgenetic evidence for
transmission of bovine spongiform
encephalopathy prions to humans. Proc
Natl Acad Sci U S A
1999;96:15137-15142.
- American
College of Physicians. Practice
strategies for elective red blood cell
transfusion. Ann Intern Med
1992;116:403-406.
- American
Society of Anesthesiologist Task Force.
Practice guidelines for blood component
therapy. Anesthesiology
1996;84:732-743.
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