MONDAY, Jan. 8, 2007 (HealthDay News) -- The rate of bleeding in the brain associated with use of the anticoagulant drug warfarin quintupled during the 1990s, University of Cincinnati researchers reported Monday.
Moreover, in people over 80, the rate of brain hemorrhages associated with warfarin, best known as Coumadin and used to thin the blood and prevent strokes, increased more than tenfold, according to the study, published in the Jan. 9 issue of Neurology.
"Warfarin use increased during the 1990s, because it was proven to be effective in preventing ischemic strokes among people who have an abnormal heart rhythm called atrial fibrillation," said the study's lead author, Dr. Matthew L. Flaherty, a neurologist.
The drug is commonly prescribed to prevent blood clotting, which can lead to ischemic stroke, the most common type of stroke. However, warfarin is associated with another type of stroke, called an intracerebral brain hemorrhage, which is a ruptured blood vessel resulting in bleeding in the brain, Flaherty explained.
In the study, Flaherty's team collected data on all patients in the greater Cincinnati area hospitalized with a first-time intracerebral hemorrhage during 1988, 1993-94, and 1999.
The researchers found that in 1988, the annual rate of intracerebral hemorrhages associated with warfarin was 0.8 cases per 100,000 people, and, in 1999, the rate was 4.4 cases per 100,000 people. Among those 80 and older, the rate increased from 2.5 in 1988 to 45.9 in 1999, they report.
Flaherty thinks that doctors need to be cautious in prescribing warfarin, especially to patients over 80. "Some of those patients are better off being on warfarin," he said. "The message isn't that no one should use warfarin. There needs to be a balance between the benefit of preventing ischemic stroke and the risk of bleeding."
Flaherty sees that this problem is one that is going to continue to increase. "We are seeing more of these patients. And we need better treatments once the bleeding has happened," he said.
For patients taking warfarin, Flaherty cautioned that it is important that they have their International Normalized Ratio (INR) monitored regularly. INR is a blood test that determines the ability of the blood to clot. If the INR is too high (above three), there is greater danger of bleeding.
Warfarin affects the INR directly and can also change the INR, depending on what other medications the patient is taking, Flaherty noted.
In addition, keeping blood pressure low is important, he added. "High blood pressure is a risk factor for bleeding, especially if you are on warfarin. So for patients on warfarin, it is doubly important that they keep their blood pressure under control."
In addition, Flaherty thinks that there needs to be more research to find safer drugs than warfarin. "Right now, warfarin is the best medication we have for preventing ischemic strokes in patients who have atrial fibrillation. There are other drugs being worked on, but, right now, none of them are available," he said.
One expert thinks that doctors need to evaluate a patient's risk of stroke versus their risk of bleeding before prescribing warfarin.
"This study demonstrates that we need to be careful when we use these therapies," said Dr. Michael B. Rothberg, an associate professor of medicine at Tufts University School of Medicine.
Not all patients with atrial fibrillation will benefit from warfarin, Rothberg added. "Not all patients with atrial fibrillation should be getting warfarin," he said. "Patients at the highest risk for stroke will benefit the most, and patients at the highest risk for bleeding will benefit the least," he said.
Rothberg noted that although warfarin is standard treatment for atrial fibrillation, not everyone with atrial fibrillation is at the same risk of stroke. "I don't think that most doctors prescribing warfarin are assessing their patient's risk of stroke and risk of bleeding, but they should be," he said.
In addition, Rothberg also believes that better INR monitoring could help reduce the problem of bleeding. "In Europe, they are doing home monitoring," he said. "Like patients who monitor their own blood sugar, there are patients who monitor their own INR."
The U.S. National Library of Medicine can tell you more about warfarin.