A newly engineered form of the blood-thinning drug heparin has proven more effective at preventing life-threatening clots in people who suffer strokes than the older version of the drug.

New Finding

The incidence of clots in the lungs and legs of stroke patients who got the engineered form, enoxaparin, was 43% lower than in those who received ordinary heparin.

The finding is potentially applicable to more than 700,000 people who suffer strokes in the US each year, said lead researcher Dr. David G. Sherman, a professor of medicine and neurology at the University of Texas Health Science Center in San Antonio. These patients are at high risk of clotting because of their forced inactivity. In fact, the 1,762 stroke patients in the study received anticoagulant treatment only if they were unable to walk.

The Study

Half of the patients were given an injection of enoxaparin, while the other half received heparin. They were then studied for the presence of blood clots in the legs and lungs.

The study included only patients who suffered ischemic stroke, the most common kind. In this type of attack a blood clot blocks a brain artery. However, Sherman said there are indications that the results also apply to people who have hemorrhagic strokes, in which a blood vessel bursts.


Cost remains a potential issue, however, because enoxaparin is much more expensive than Ordinary heparin. Sherman's group is working on an analysis determining the economic impact of a shift to using enoxaparin on the total cost of treating stroke.

One prior study has indicated that introducing the drug might actually lead to cost reductions, said Dr. Richard M. Weinberg, chief quality officer of the Stamford Health System in Connecticut. His team tracked costs across 33 hospitals.

"There are several possible explanations for the lower overall cost," Weinberg said. "Most patients getting Lovenox (enoxaparin) can be managed without the frequent tests needed for heparin. In addition to reduced laboratory testing, a reduction in the length of stay and less time spent in the ICU intensive care unit) are possible explanations."

"This is the first big trial in which the two treatments have gone head to head," said Sherman. "Enoxaparin pretty convincingly appears to work better."

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