Doubt Cast on Use of Genetic Test Before
WEDNESDAY, Dec. 28 (HealthDay News) -- A new review of existing
research suggests that, despite a federal recommendation, genetic
testing won't help physicians determine which heart patients should
get Plavix, a blood-thinning drug used to treat certain cardiac
Plavix, also known as clopidogrel, is used to treat or prevent
blood clots due to the clogging of arteries and after such surgical
procedures as balloon angioplasty.
But some patients won't experience the drug's clot-preventing
benefits if their bodies don't process it properly, potentially
leading to heart attack, blood clots in stents and death, according
to Dr. Jean-Sebastien Hulot, associate professor of medicine at the
Cardiovascular Research Center at Mount Sinai School of Medicine.
Or, he said, they could experience the reverse -- excessive
bleeding if the medication has too much of an effect. Hulot was not
involved with the study, but is familiar with the findings.
The U.S. Food and Drug Administration believes that genetic
testing could help identify patients who won't respond well to the
drug. But the American Heart Association and the American College
of Cardiologists have been skeptical that the genetic testing in
question is useful.
In the new review, Dr. Michael V. Holmes of University College
London and colleagues examined 32 studies that included over 42,000
patients. They looked for signs of bleeding problems, blood clots
in stents and cardiovascular problems.
They also conducted a meta-analysis in which they examined
statistics in the studies as a whole.
While they mention some statistical caveats, the researchers
found that a specific genetic trait -- linked to the body's ability
to respond to the drug -- did not significantly affect the risk of
In a commentary accompanying the study, Dr. Steven E. Nissen,
borrowing a phrase from a former chairman of the Federal Reserve,
wrote, "It now appears that the FDA warning reflected a case of
Nissen, chair of cardiovascular medicine at the Cleveland
Clinic, noted that the review has limitations. But, he added, for
the time being physicians should "rarely, if ever" use the genetic
testing in question and should "interpret the results with
Hulot, the Mount Sinai School of Medicine professor, is
skeptical. He said the findings are "far from convincing" and
questioned their statistical validity. He also pointed to an
earlier study, also a meta-analysis, that suggested a genetic trait
did indeed boost the risk of problems for those who took the drug
in certain cases.
The study is published in the Dec. 28 issue of the
Journal of the American Medical Association.
For more on
Plavix (clopidogrel), visit the U.S. National Library of Medicine.
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