Warfarin Blood Thinner Underused in High-risk Stroke Patients

Warfarin, an inexpensive blood thinner used to diminish the risk of additional strokes in elderly stroke patients, is used in only half of eligible patients, according to an article in the Oct. 26 issue of the AMA’s Archives of Internal Medicine.

Lawrence M. Brass, M.D., director of Stroke Research at the Center for Outcomes Research and Evaluation at Yale-New Haven Hospital, presented the study today at the AMA’s 17th Annual Science Reporters Conference in Durham, North Carolina. (On the day of the media briefing, call the AMA’s Science News Department at 312/464-5374 or 5904.)

Brass, professor of epidemiology and public health and of neurology at the Yale School of Medicine, and his colleagues studied the use of warfarin among a sample of 278 elderly patients from Connecticut age 65 years or older. The patients were experiencing atrial fibrillation (irregular heart beat) and were hospitalized for ischemic stroke.

According to the authors, elderly stroke patients with irregular heart beats are at especially high risk for additional strokes, with an annual recurrence rate of more than 10 percent per year. Warfarin has been shown to be highly effective in reducing risk (by two-thirds) in this group. The use of warfarin has also been demonstrated to decrease mortality and to be cost-effective.

“In this high-risk group, it costs about $15,000 in testing and medications to prevent a stroke. The average total cost for a 65-year-old patient with a stroke in the United States is $100,000. So you spend $15,000 to save $100,000,” Brass said.

The researchers found that only 53 percent of the stroke victims were prescribed warfarin at discharge. Among the patients not prescribed warfarin, 62 percent were also not prescribed aspirin, another drug which makes the blood less likely to clot.

The authors wrote: “Our work demonstrated that, even for this very high-risk population, anticoagulation therapy appears underused…. Even when we restricted our analysis to those without a contraindication to anticoagulation, it appears that only half of eligible patients are receiving anticoagulation therapy.”

The researchers believe there may be several reasons why warfarin is underused, including misperceptions about its efficacy in the elderly. “The concern is that older individuals are at higher risk for bleeding complications, especially intracranial hemorrhage. However, these same patients are also at increased risk for recurrent stroke,” Brass said.

To address the issue of underutilization of anticoagulation, the researchers suggest: – Clinicians integrate data from many different sources, including the results of new clinical trials and management guidelines. – Using simple, individualized reminders designed to change physician behavior (telephone or written follow-up). – Computer-based alerts to improve compliance with treatment guidelines. – Having physicians clearly document their reasons for not using anticoagulation therapy.

“We have identified an important therapy that is not being used. The reasons why this occurs and how physician practices can be improved are critical next steps,” the researchers concluded. “The low use [of anticoagulant therapy] even among ideal candidates indicates that there is room for wider application of these preventive therapies following stroke. Acute care hospitalization is a ready-made opportunity to initiate anticoagulation, and the increased use of warfarin among these patients represents an excellent opportunity for reducing the risk in this high-risk population.”

The authors also recommended “innovative educational and system- improvement projects” to encourage clinically effective, affordable preventive therapies. Those that are shown to be the most effective should be implemented as part of governmental and public health care programs to improve outcome, reduce mortality, and increase the cost-effectiveness of care for patients at risk for strokes, Brass said.