Jewish World Review Dec. 13, 2002 / 8 Teves, 5763
By Robert A. Wascher, M.D., F.A.C.S.
http://www.NewsAndOpinion.com |
Anemia, or low red blood cell count, is a very common condition in
critically patients admitted to intensive care units (ICU). Recombinant
human erythropoietin (rHuEPO) is a hormone that is produced by cloning human
genes for this protein into bacteria, which then produce the rHuEPO protein
in large quantities. Erythropoietin is a hormone that is naturally produced
in the kidneys, and stimulates the bone marrow to produce and release red
blood cells into the bloodstream (where they pick-up oxygen from the lungs,
and distribute it to all of the body's cells).
Approved by the FDA in 1989,
rHuEPO was initially used to treat the severe anemia present in patients
undergoing hemodialysis for kidney failure. The drug is now commonly used,
along with other recombinant drugs that stimulate the bone marrow to produce
white blood cells and platelets, to treat the anemia of patients undergoing
chemotherapy for cancer, and as an alternative to blood transfusions in
chronically or critically ill patients with severe anemia. However, rHuEPO
is not cheap.
A typical dose retails for $500-1,000, and must be given once
or twice a week. It is, therefore, important to determine if the use of
rHuEPO in critically ill patients can actually decrease the need for blood
transfusions, and whether or not the drug improves patient outcomes overall.
There is certainly some evidence to suggest that patients who receive blood
transfusions may be at increased risk of developing infection, and in the
case of patients with cancer, an increased risk of cancer recurrence as
well.
Of course, blood products may also contain infectious disease-causing
organisms such as the viruses that cause hepatitis and AIDS, among other
nasty bugs (although modern blood screening in the United States has reduced
that risk to about one out of every two million units of transfused blood).
Allergic reactions, occasionally life-threatening in severity, may also
occur with transfusions. So, if a relatively nontoxic drug like rHuEPO can
significantly reduce the need for blood transfusions among critically ill
patients, then many patients could potentially be spared the risks of
transfusion.
In this week's Journal of the American Medical Association (JAMA) is a study
that evaluated the use of rHuEPO in anemic ICU patients as a means of
preventing or reducing the need for blood transfusions. The study looked at
more than 1,300 ICU patients in 65 different hospitals between December 1998
and June 2001.
A total of 650 patients were randomized to receive weekly
rHuEPO injections, and the remaining 652 received placebo injections of
saltwater only. The study confirmed that the ICU patients who had received
rHuEPO required a significantly decreased number of blood transfusions when
compared to the placebo group. Patients receiving rHuEPO were 33% less
likely to require a blood transfusion for anemia than their placebo group
counterparts. Among those patients receiving rHuEPO who did require blood
transfusions, 19% fewer units of red blood cell transfusions were required
when compared to patients who had not received the rHuEPO injections.
These results confirm my own observations in my practice as a cancer
surgeon. While patients with profound anemia (or patients with moderate
anemia and underlying diseases that make them intolerant of a low red blood
cell count) still often require blood transfusions, I manage most of my
patients with well-compensated moderate anemia using rHuEPO injections. For
patients with more severe anemia, or with signs of significant
cardiovascular stress secondary to anemia, a combination of rHuEPO
injections and judicious blood transfusions are often sufficient to raise
the red blood cell count to an acceptable level.
The JAMA study did not
identify any improvements in patient complications or death rates, but this
is not surprising in view of the relatively short duration of the study, and
the rather small number of patients studied. The complications associated
with transfusion-related infections often take many years to become
clinically apparent following blood transfusion. The study's conclusions
are important in that they confirm that rHuEPO, when used in the proper
setting, can significantly reduce the need for blood transfusions in
critically ill patients.
At the same time, as pointed out in an
accompanying JAMA editorial, you would have to treat approximately 10
patients with rHuEPO to avoid transfusion in one patient. Also noted is the
persistent belief by many physicians that red blood cell levels (referred to
as the hematocrit) must be kept at a relatively high concentration for most
patients. Traditionally, physicians have been taught that the hematocrit
should not be allowed to fall below 30%.
However, recent research suggests
that the hematocrit can be allowed to decline to as low as about 20-25%
before most patients will begin to experience serious side effects from
their anemia. Thus, lowering the transfusion threshold for hematocrit
values would, in and of itself, spare many anemic patients a transfusion.
Unfortunately, most of the research that has advocated the safety of lower
hematocrit values did not study ICU patients who were critically ill. While
the JAMA study has not completely addressed all of the controversies
relating to blood transfusion, it nonetheless provides interesting and
useful data to physicians and patients alike.
ALCOHOL CONSUMPTION & RISK OF BREAST CANCER
CALCIUM INTAKE & PROSTATE CANCER RISK
This finding contradicts research published last year that
suggested high dietary calcium levels were associated with an increased risk
of developing prostate cancer. Ultimately, it will require a very large
international multicenter trial, involving thousands of study volunteers, to
definitively determine the role, if any, of calcium intake in the
development of prostate cancer. Still, it is important to note that this
study did not identify any increase in the risk of developing prostate
cancer among men with high levels of calcium in their diet.
JWR contributor Dr. Robert A. Wascher is a senior research fellow in molecular & surgical oncology at
the John Wayne Cancer Institute in Santa Monica, CA.
Comment by clicking here.
Reducing blood transfusions in critically ill patients
British Journal of Cancer: A large European study of over 58,000 women with
breast cancer and 95,000 women without breast cancer suggests that heavy
alcohol consumption increases the risk of developing breast cancer. When
compared to nondrinkers, women who consumed one glass of wine or beer per
day, or one shot of liquor per day, experienced a 7% increase in lifetime
risk of developing breast cancer. Women who consumed six or more glasses of
alcoholic beverages experienced a 46% increase in their lifetime risk of
developing breast cancer. Past studies have revealed contradictory
conclusions regarding the effects of alcohol consumption on breast cancer
risk. This study strongly suggests that heavy and regular drinking can
substantially increase a woman's lifetime risk of developing breast cancer.
Journal of Urology: A new study looked at the level of calcium intake in
the diet, and analyzed the effects of calcium intake on prostate cancer
risk. A total of 454 male patients, aged 46 to 92 years, were included in
the study. Sixty-nine of these men were diagnosed with prostate cancer
during the course of the study. Following diet surveys and data analysis,
the study concluded that high levels of calcium intake did not appear to
correlate with either an increase or a decrease in the risk of prostate
cancer.
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