Jan. 10, 2007
 
HEALTH: Risks of Blood Thinner Cited in Study
 
By Lee Bowman
Scripps Howard News Service
 
Rates of brain hemorrhages associated with the use of blood-thinning drugs increased by five times during the 1990s, and rose tenfold in people 80 and older, according to a new study published this week.
 
Writing in the journal Neurology, researchers at the University of Cincinnati said they built a database of all patients in the greater Cincinnati area hospitalized for the first time with a stroke caused by bleeding within the brain during three periods: 1988, 1993-94 and 1999.
 
In 1988, the annual rate of hemorrhages associated with use of blood-thinning drugs was .8 cases per 100,000 people. In 1999, the rate had increased to 4.4 cases per 100,000 people. And for people 80 and older, the rate increased from 2.5 per 100,000 in 1988 to 45.9 in 1999.
 
The researchers attribute almost all the increase to greater use of the blood-thinning drug warfarin. Prescription of the drug increased during the 1990s after studies showed it reduces the risk of ischemic stroke (caused by blood clots in the brain) among people with atrial fibrillation, a condition that causes irregular heart rhythm and becomes more common as people age.
 
The abnormal rhythm condition, which is marked by rapid contractions of the heart, increases the likelihood that blood clots will form that can travel to the brain and raises a patient's overall risk for a stroke fivefold. It is believed to account for about 80,000 blood-clot-induced strokes, which represent 80 percent of all strokes, each year.
 
Thus, the Cincinnati study, like some previous research, suggests that despite the increased risk of bleeding strokes, "for many people, the benefits of preventing ischemic stroke continue to outweigh the risk of a hemorrhagic stroke," said Dr. Matthew Flaherty, a neurologist and lead author of the study.
 
In another study published last summer, researchers from California and Massachusetts followed more than 13,000 patients with atrial fibrillation for an average of about two-and-a-half years and found that 170 taking warfarin suffered major brain hemorrhages, compared with 162 episodes for patients who were not taking the blood thinner.
 
"Our findings showed that although older patients have a greater risk for hemorrhage, the overall likelihood of hemorrhage on warfarin is relatively small, especially when one considers the benefits of stroke prevention," said Dr. Margaret Fang, an assistant professor of medicine at the University of California-San Francisco and the lead author of that study.
 
Flaherty said while his team's findings plot an increase in the incidence of bleeding strokes linked to use of the blood thinner, the study "should not discourage the use of warfarin when appropriate.
 
"Doctors can use these findings to make sure they are weighing the risks and benefits of warfarin use for their patients. And the results may stimulate efforts to develop safer alternatives to warfarin and better treatments for people with brain hemorrhages."
 
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