Anticoagulant Takers Can Safely Test Blood at Home

At-home blood tests are safe for people taking a common blood thinner.

October 20, 2010, 4:19 PM

Oct. 23, 2010— -- Sometimes it's a weekly trip to the clinic for Patricia Slattery, sometimes it's every two. At one point, she was visiting the doctor three times a week to get her blood drawn.

About three years ago, Slattery was diagnosed with deep venous thrombosis, a condition in which blood clots form in deep veins in the body. Doctors put her on warfarin, an anticoagulant that prevents blood clots. Those on the medicine must tightly monitor their blood to make sure they are getting an adequate, but safe, dose of the drug.

The result is an intricate, daily balancing act for these patients.

"It's a bit of a pain to get checked, but I can't complain because the medicine saved my legs," said Slattery, a 69-year-old resident of Baltimore, Md. "It's an important part of my life now, so if I have anything planned and then I have to suddenly get my blood taken, I'll cancel."

Warfarin is the most widely prescribed blood thinner in the United States; about 2 million people take the drug on any given day.

While the monitoring usually takes place in a doctor's office, a new study from the Veterans Affairs Medical Center found that an at-home weekly test may be just as safe and effective as a monthly blood draw in the doctor's office.

"We need strategies to make warfarin anticoagulation easier and safer," said Dr. David Matchar, co-author of the study and director of the Health Services Research Field Program at Duke-NUS Medical School in Singapore. "The availability of devices that can provide results comparable to high-quality clinic care should encourage people at high stroke risk and their doctors to use this treatment, and to be assured that they can use it well."

About a year ago, Rick Pero was diagnosed with atrial fibrillation, a condition where the heart beats irregularly, and Pero was also put on warfarin. Now, every two weeks, Pero leaves work early to drive 45 minutes to a health center to get his finger pricked.

"If I had a self-test that I could use at home, it would save me a lot of time, especially since I have to use an hour of sick time every time I leave work to get my blood drawn," said Pero, a maintenance director in Wolfeboro, N.H.

Patricia Slattery agreed that a home test would make life more convenient.

"If I had a monitoring system in my own possession, it'd be much easier, and I could get the results to my doctor even quicker than he gets them now," said Slattery.

New At-Home Option for Warfarin Users

The study, published on Wednesday in the New England Journal of Medicine, involved 2,922 patients who were taking warfarin and capable of using a self-testing home device, similar to a finger stick glucose test for diabetic patients. It's important to note that, in past studies, weekly self-testing proved to be better at reducing the risk of stroke, death, and major bleeding events than a monthly doctor's visit. But after two years of follow-up, this study showed that the self-test and the clinic tests were similar in result.

"Since we did not find a difference in these events between the two testing groups, we were surprised by the results," said Dr. Rowena Dolor, co-author of the study and assistant professor in the internal medicine division at Duke University Medical Center in Durham, N.C. "This study was conducted within high-quality anticoagulation clinics and the lack of the difference between office testing and home testing may be due to the high level of anticoagulation care received in the VA setting."

Dr. Rajabrata Sarkar, chief of vascular surgery at the University of Maryland Medical Center, said that the study results were likely due to the caliber of the hospital.

"I don't think these results are reproducible community wide in America," said Dr. Sarkar, who has many patients taking warfarin. "Not everyone has access to this high quality of care, so the home testing is an excellent alternative for people who have geographic or economic barriers but still have to come into the clinic to get checked."

"So, if the quality of anticoagulation care is lower in a different hospital setting, home testing may have been shown to be a better alternative than the office visit," continued Dolor.

Usually, patients on anticoagulant medication visit their doctor at least once a month to get blood drawn. If the levels are too high or too low, the medication is adjusted.

New treatments are being researched for people on anticoagulant drugs. On Wednesday, the FDA approved dabigatran, an orally active direct thrombin inhibitor, which would not require regular blood monitoring. This could soon be the preferred medication. But, for those who will stay on warfarin, self-monitoring might lead to an easier solution for the drug.

"Effective use of home monitoring makes a whole lot of sense for warfarin," said Dr. Daniel Brotman, associate professor of medicine at Johns Hopkins Hospital. "My recommendation to patients has always been that they should not go to once-monthly check until they're on a stable regimen and their dose hasn't changed during a one or two week period of time. And some patients never get to that point, so a weekly self-check would be good."

A lot of things can affect these levels, said Brotman, including new medicines, change in diet and exercise. Self-tests would allow patients to be more involved and pro-active, much like other home kits for a variety of conditions on the market.

There's No Place Like Home

Home tests have become a major part of the healthcare system. Today, a person can walk into a pharmacy and pick up a test to check for pregnancy, UTIs and HIV. Kits for diabetics are available to check their blood sugar levels at home.

Dr. Gerald Bernstein, director of the Diabetes Management Program of the Friedman Diabetes Institute at Beth Israel Medical Center, said that education is important with any self-administered test. At the Friedman Diabetes Institute, diabetes educators are on hand to teach patients how to use their equipment and answer questions about the disease.

"As with all home tests, it's important to know what the quality of the testing equipment is at home," said Bernstein. "I'd want to know the quality of the testing equipment, if it's easy enough to use, and if the results are reliable enough."

Dr. Joanna Cain, the chair of the department of Obstetrics and Gynecology at the Warren Alpert Medical School of Brown University, said she prescribes Coumadin to many of her cancer patients.

"It would make their lives much better if they could test at home so they don't have to schlep in to get their blood drawn all the time," said Cain. "But we as a country have not been very good about supply coverage for the kind of education and health professional support for even things like diabetes, let alone something like this where the dosage change could be significant with a significant impact."

"The self-test is a great idea," continued Cain, "but it has to come hand in hand with training and education that would let me know my patients would be safe."

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