Monitoring dose crucial for anticoagulants

Physicians find it a challenge to manage patients' progress on these decades-old but still important drugs.

By Susan J. Landers — Posted July 3, 2006

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William Thomas, MD, a geriatrician who has written extensively on improving the lives of elderly people, wishes that the anticoagulant warfarin glowed bright orange so patients would be reminded that this is a pill of a different color in more ways than one. He's not sure all patients know this one little pill can have such a good -- or bad -- effect on health.

Surveys commissioned by a Washington, D.C.-based advocacy group, the National Consumers League, for its SOS Rx project reinforce that view. Participating patients revealed that they need more help from their physicians or other health care professionals to manage this therapy successfully. Physicians surveyed also indicated that monitoring patients on anticoagulants often was a challenging undertaking.

Dr. Thomas joined NCL representatives and others for a May 31 briefing about the surveys and about anticoagulants in general.

About 4 million Americans currently take the medication warfarin to prevent strokes, blood clots and other serious health problems, according to the league. But despite their frequent use and long history -- warfarin has been around for more than 50 years --anticoagulants remain difficult to manage. Close blood monitoring requires frequent office or lab visits, and dangerous interactions can occur with many other medications, herbal supplements, vitamins and food.

According to NCL's patient survey, of the 426 users of anticoagulants queried, 93% had experienced adverse reactions such as bleeding, bruising or dizziness, but only about half changed their behavior to prevent the reaction from reoccurring. Many had not even reported the symptoms to their physicians.

"The results are disturbing," said Linda Golodner, NCL president. "Consumers who take blood thinners without direct involvement from health care providers are walking a thin line between positive benefits and life-threatening health risks."

Because of the findings, the NCL has created a Web site, (link), to provide patients resources on the safe use of anticoagulants.

Constant adjustment needed

The problems involved don't surprise Samuel Z. Goldhaber, MD, director of anticoagulation services at Brigham and Women's Hospital in Boston. "Warfarin is the only modern medication that we dose according to a trial-and-error method," he said. "For all other medications, we have a particular fixed dose or a dose according to someone's weight or renal function."

Despite the difficulties, physicians have no alternatives to warfarin, and they have to get the dose just right. "Give too high a dose, and catastrophic bleeding could result. Too low a dose, and stroke and fatal pulmonary embolism can follow," he said.

To improve treatment, Dr. Goldhaber advises patients and physicians to use centralized anticoagulant centers for closer monitoring. Such centers have the staff to attend to any dose adjustments. But the downside is that a lot of the reporting to patients is carried out by telephone and is not reimbursed by insurers.

Primary care physicians also can set up their own office-based anticoagulation clinics, said John Spandorfer, MD, associate professor of medicine at Jefferson Medical College in Philadelphia. The clinic head, whether a nurse or other staff member, would ensure that patients return for periodic blood tests. "This is very helpful for primary care physicians," he said. Having a point-of-care monitor in the office also would mean that test results would be available immediately and that medication could be adjusted as needed.

Another option is for patients to monitor their blood at home like people with diabetes monitor their blood glucose levels. They then could report the results to the physician. A monitoring machine costs about $1,500, but reimbursement would be unlikely.

Even with the closest monitoring, though, patients maintain their target blood rates only 65% of the time on warfarin, Dr. Goldhaber said.

Meanwhile, other anticoagulants are making their way through the pharmaceutical pipeline, although recent clinical trials of promising new drugs have been disappointing. Genetic testing to determine proper dose is another option if warfarin remains the sole choice. Results already have shown potential, and physicians predict that such tests will become routine in the next five to 10 years.

The survey also found that many patients on anticoagulants are in poor health. In the past year, 41% reported seeing at least four physicians in addition to their primary care doctor, and 40% went at least once to an emergency department. The average respondent said he or she took seven prescription drugs regularly, thus increasing odds of a drug interaction.

The 101 primary care physicians queried said care for anticoagulant patients is challenging, requiring them to spend more time with those patients than with others who have other chronic conditions.

The survey also underscored the need for improved communication between physicians, patients and the patients' caregivers. Patients said their physicians didn't offer reminders about lab work or appointments and sometimes failed to provide feedback on test results. About one-third of patients said their physician had not asked whether they were having problems and that they found it difficult to contact their doctors by phone.

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External links

National Consumers League's SOS Rx Coalition, an senior outpatient medication safety group (link)

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