Blood thinner linked to brain bleeding

Older people who take the popular blood-thinning medicine warfarin to prevent heart attacks or strokes might be at greater risk for serious brain hemorrhage, according to a new study.

Scientists at the University of Cincinnati College of Medicine found that use of the anticoagulant medicine increased in the 1990s, and the surge in prescriptions caused a rise in the number of drug-induced intracerebral hemorrhages, especially in people over age 80.

“We’ve had no idea how often this was happening,” said Dr. Matthew Flaherty, lead author of the study that appears in the journal Neurology. Use of the drug increased after studies showed warfarin was effective at preventing ischemic strokes in people with an abnormal heart rhythm.

The new study suggests warfarin, which is sold under many brands including Coumadin, might cause problems of its own.

Ischemic strokes are caused by a blood clot that forms in the brain or travels to the brain. The less common form of stroke is an intracerebral hemorrhage – a blood vessel bursting in the brain.

Initial studies showed warfarin as a better preventive measure than aspirin or a placebo. But the Cincinnati scientists were the first to quantify how often a drug-related hemorrhage occurs in a large population. The scientists studied hospital admissions during the late 1980s and 1990s and found the incidence of warfarin-related cerebral hemorrhages increased. People over 80 were especially vulnerable. From 1988 to 1999, the incidence jumped from 2.5 per 100,000 patients to 45.9. There was a fourfold increase in the incidence among all ages, from 0.8 to 4.4 per 100,000.