Research Highlights
Self-monitoring of anti-clot drug has some pluses
December 1, 2008
The results of a VA clinical trial involving nearly 3,000
veterans at 28 VA medical centers, presented Nov. 12 at the
scientific meeting of the American Heart Association, may help
doctors decide on the best way to manage patients taking the drug
warfarin to prevent harmful blood clots.
Traditionally, doctors monitor patients on warfarin, sold as
Coumadin, over several visits. They test how fast the blood clots
and adjust the dose accordingly: Too low a dose won't prevent
clots, and blood flow to the heart, brain or other areas of the body
could be blocked. Too high a dose could lead to internal bleeding.
Nowadays, patients have the option of tracking their own
response at home using handy blood analyzers known as INR
monitors. INR stands for international normalized ratio—a measure
of how fast the blood clots. Patients do a finger-stick, apply a drop of
blood to a test strip, and feed the strip into the device. The procedure
is not unlike that used by people with diabetes to check their blood
sugar. Warfarin patients can then convey the results to their doctor or
nurse without having to come into the clinic.
The VA study aimed to test how well patient self-monitoring
works. Most importantly, would it help prevent negative outcomes
such as strokes or bleeding incidents?
The answer, according to the five-year study, is no. While the
outcomes overall were better than those found in most non-VA
studies, there was no significant difference between patient selftesting
and a more conventional approach—"high quality"
management by a health care team—in terms of strokes, major
bleeding incidents, or death.
"The data show that any extra benefit of patient self-testing
would be modest at best," said study co-leader David Matchar,
MD, an internist with the Durham VA and Duke University School
of Medicine.
More on the Home INR Study
- Included 2,922 patients from 28 VA medical centers.
- 98 percent of patients were male, average age 67.
- Study began in 2003 and ended in 2008.
- Funded by VA’s Cooperative Studies Program.
Self-testing, however, did boost patients’ satisfaction with
warfarin therapy and increase the amount of time they were in the
appropriate dose range.
Study co-leader Alan Jacobson, MD, a cardiologist and researcher
with VA and Loma Linda University School of Medicine, suggested
that one take-home message of the study is that "patients who are
being systematically monitored—no matter by what means—are
likely to have good outcomes." He said self-monitoring may be a
good option for many patients, especially for those who live in rural
areas or who otherwise have difficulty getting to a clinic.
This article originally appeared in the Nov/Dec 2008 issue of VA Research Currents.
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