WEDNESDAY, Oct. 20 (HealthDay News) -- If you're taking the
blood-thinning medication warfarin, a new study suggests that you
might not always need to visit the doctor to get your medication
The study, which is published in the Oct. 21 issue of the
New England Journal of Medicine, found that weekly home tests were similarly effective to monthly clinic testing for patients taking warfarin therapy.
The study compared clinic-based testing to home testing for
about 3,000 patients taking the anticoagulant drug, explained one
of the study's authors, Dr. Rowena Dolor, an assistant professor in
the division of internal medicine at Duke University Medical
Center, and a staff physician at the Veterans Affairs Medical
Center in Durham, N.C. "While the study showed no difference in
long-term outcomes, those on home testing spent more time in the
target range for medication levels," she said.
Blood-thinning drugs such as warfarin, also known as
anticoagulation therapy, are prescribed to help keep the blood from
clotting excessively, as this can cause ischemic strokes or heart
attacks. However, too much of these medications can also cause
problems, such as serious internal bleeding or a hemorrhagic
The reason it's so hard to find the right balance is that many
factors affect the way these medications are utilized in the body.
Everyone needs an individualized dose -- the foods you eat and
other drugs can change the effectiveness of the blood-thinning
medication, said Dr. Marc Siegel, an internist at the NYU Langone
Medical Center in New York City.
To avoid these complications, people on these medications have
to have their blood frequently monitored, especially when first
starting therapy. Until recently, this meant a visit to the
But now, several devices are available for home testing. The
cost of the devices averages around $2,000, according to Dolor, and
the supplies for each test cost about $5 to $10. In 2002, Medicare
approved coverage for home testing for patients on anticoagulation
therapy with prosthetic heart valves, and in 2008, it expanded the
availability of home testing to those who need long-term
anticoagulation therapy, such as people with the heart condition
In the current study, the researchers randomly assigned 2,922
people who were taking warfarin because they had a mechanical heart
valve or had atrial fibrillation to either test weekly at home or
monthly in a clinic.
The patients used finger-stick devices approved by the U.S. Food
and Drug Administration for home use. They were trained to use the
devices, which measure how fast the blood clots, and the results
were phoned in to a physician's office to discuss changing the
medication dose as needed.
The study volunteers were then followed for between two and 4.75
years, according to the study.
A total of 164,626 home tests were performed, and about 87
percent of the study volunteers adhered to their home testing
Over the study period, 271 people in the home-testing group had
a stroke, a major bleeding event or died, compared to 285 in the
clinic-tested group. The self-testing group reported significantly
more minor bleeding episodes, but it had a small, but statistically
significant improvement in the time patients spent in the target
range for the medication.
The home-test group also reported slightly higher patient
satisfaction scores, according to the study.
Dolor said the researchers didn't design the study to figure out
why the home-test group might be more satisfied, but suggested that
the convenience of home testing and not having to go out to the
doctor's office likely play a role. She said that patients may also
feel more in control, and may feel that they have a better
understanding of their condition.
"More frequent monitoring is much safer and ideal. If the technical accuracy of home monitoring is the same, and we can be assured that the patient is using home monitoring properly, then I don't have a problem with it," said Siegel.
Although the current study didn't find a significant difference
in preventing serious outcomes, Dr. L. Bernardo Menajovsky,
director of the anticoagulation clinic at the Scott and White
Healthcare Center for Diagnostic Medicine in Temple, Texas, noted
that a significant number of healthier people were enrolled in
"About 40 percent of the study population were at low risk to have bad outcomes," he said, adding that if the researchers had been able to look at more people in a high-risk group, they may have seen an improvement with the more frequent home monitoring.
But, "home testing alone isn't going to be the answer [for
improving complications]. We need good patient education, and after
that, the next step is home management," he said, explaining that
people could be trained to test themselves and then make
adjustments to their medication doses, similar to the way diabetes
The study was sponsored by the VA's Cooperative Studies
To learn more about blood thinners, visit the
Agency for Healthcare Research and Quality.