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Concern about dosing risk leads to underuse
Anticoagulation therapy presents a dilemma for physicians: Warfarin prevents strokes among patients with atrial fibrillation, but it also increases the risk of major bleeding. As a result, less than half the appropriate candidates receive the drug.1
Wider use of warfarin requires better monitoring. Physicians can accomplish that by using an anticoagulation service to monitor patients — or allowing them to track their own care through self-testing kits.
"An anticoagulation clinic is a focused and coordinated approach to care," says Jack Ansell, MD, professor of medicine and vice chairman of the department of medicine at the Boston University School of Medicine. "That is what is often lacking in a routine or haphazard system."
In fact, the Anticoagulation Forum, a loose-knit international network of about 500 anticoagulation clinics based in Boston, has seen a steady growth in membership since its founding in 1991. "In the last five to eight years, there has been a rapid rise in the number of anticoagulation clinics to smaller hospitals, group practices, managed care organizations, and other providers of health care as they see the benefits of such clinics," Ansell says.
Patients generally visit an anticoagulation clinic at least monthly to check their prothrombin time, or time to clotting. Often, that testing time frame is weekly or biweekly, and if patients are having difficulty with their dosage, they may come in more than once a week.
Nurses or pharmacists at the clinic have the authority to alter the dosage of the medication to improve its effectiveness and reduce risks of bleeding.
Patient self-testing involves just a finger prick and eliminates the inconvenience of coming to a lab or office for the monitoring. Ansell likens it to the self-management of diabetic patients who monitor their need for insulin.
Although the effectiveness self-testing hasn’t been compared to anticoagulation clinics, "there is good evidence in the literature that it leads to good patient care and reduced complications as compared to routine or usual care,"3 says Ansell. "I think that patient self-management will be a very important model of care in the future."
Some physicians may be reluctant to send their patients to clinics for monitoring for fear of fragmenting their care.
With the help of tracking software such as a program called CoumaCare from Dupont, the pharmaceutical firm that manufactures Coumadin, the clinics can tell whether patients are following up on their appointments.
Do anticoagulation clinics improve outcomes? That is a major question that is being addressed by the Managing Anticoagulation Services Trial, led by David Matchar, MD, director of the Center for Health Policy at Duke University in Durham, NC.2 Six sites served six to 10 medical groups. A control group continued with their usual methods of prescribing and monitoring warfarin use.
So far, both physicians and patients seem to be responding favorably to the clinics, says Greg Samsa, PhD, associate professor at the Center for Clinical Health Policy Research. "In an entirely different study yet in progress, we found that patients followed by the anticoagulation service tended to come back more frequently [for testing]," he says. "They often seem to establish a fairly close relationship with the anticoagulation service provider. That may be one thing that encourages the patient to come back more regularly."
But Ansell notes, "With Coumadin, the potential complication rate of major bleeding or thrombosis can be so high and serious that such clinics may well be worth the extra visit outside of one’s usual primary care doctor.
"I do not favor setting up a small clinic for every disease entity or problem," he says. "But I think that this is in a class of its own."
Financially, it may be difficult for an individual group practice to set up an anticoagulation clinic, particularly since the reimbursement of services may be limited. But physicians could accomplish much the same by setting aside a particular day or time to see warfarin patients and assigning follow-up duties to a nurse or other staff member.
1. Stafford RS, Singer DE. Recent national patterns of warfarin use in atrial fibrillation. Circulation 1998; 97:1,231-1,233.
2. Samsa GP, Matchar DB, Cohen SJ, et al. A seven-step model for practice improvement research: Description and application to the Managing Anticoagulation Services Trial. New Medicine 1998; 2:139-146.
3. Ansell JE, Patel N, Ostrovsky D, et al. Long-term patient self-management of oral anticoagulation. Arch Intern Med 1995; 155:2,185-2,189.