The decision to initiate anticoagulation treatment is one of the most difficult in the practice of geriatrics. The difficulty stems from concern about the adverse effects of bleeding complications, particularly intracranial hemorrhage. Warfarin is most commonly prescribed for the prevention of stroke in patients with atrial fibrillation and for long-term treatment of deep venous thrombosis, as discussed in the article by Ahktar and colleagues in this issue of AFP
Although anticoagulation treatment for deep venous thrombosis is widely used in elderly patients, warfarin therapy is underused for stroke prevention in geriatric practice. Physicians and patients do not place similar values on the importance of the measures for stroke prevention.2
The prevalence of atrial fibrillation sharply increases with age (i.e., from 2 percent in persons younger than 50 years to 16 percent in persons 75 years of age and 22 percent among nursing home residents aged 91 to 103 years). The rate of embolic stroke complications from atrial fibrillation also increases with age. It is estimated that about 36 percent of all strokes in patients 80 years or older may be attributed to atrial fibrillation.3
Strokes associated with atrial fibrillation usually cause more profound neurologic deficits than do other types of strokes. This is ascribed to lack of a compensatory mechanism provided by collateral circulation in these patients, unlike patients with other types of strokes. Seventy-one percent of strokes associated with atrial fibrillation are fatal or result in dependency requiring extensive rehabilitation and restorative nursing home care.4
Elderly patients are very apprehensive about the prospect of becoming disabled because of a stroke. When asked about choosing between the risk of bleeding complications and the inconvenience caused by treatment with warfarin compared with the risk of stroke from untreated atrial fibrillation, they overwhelmingly prefer treatment. For many elderly patients, the prospect of stroke-related disability is “worse than death.”2
Nonetheless, physicians appear reluctant to initiate this treatment in elderly persons. For example, one study5
showed that only 25 percent of elderly hospitalized patients at high risk of stroke were found to be receiving warfarin therapy, while as many as 50 to 70 percent could potentially benefit.5
The reasons cited in the literature for underuse of treatment with warfarin in the elderly are the following: lack of information on the treatment effectiveness in stroke prevention, exaggerated perception of the high risk of major bleeding complications and inconvenience caused by this treatment in elderly patients.6
The effectiveness of treatment with warfarin for stroke prevention is well documented in patients of any age with atrial fibrillation. For patients older than 75 years, treatment with warfarin reduces the rate of stroke associated with atrial fibrillation by about 70 percent (84 percent in women). According to an analysis of pooled data from five major randomized controlled studies,7
this benefit was 23 times greater than the rate of drug-induced complications in the elderly. Also, the most recent studies on the safety of warfarin treatment in the elderly cast doubt on the notion that the risk of bleeding is inherently higher in the elderly. The risk is only increased when the intensity of warfarin therapy exceeds the therapeutic need (i.e., when the International Normalized Ratio [INR]—the most appropriate means of monitoring anticoagulation treatment—is above the therapeutic level of 2.0 to 3.0). When the INR is above 3.0, and particularly when it is 4.5 or higher, the risk for intracranial hemorrhage complications in the elderly increases.
In one frequently cited study—the Stroke Prevention in Atrial Fibrillation II Study8
—a high rate of intracranial hemorrhages was observed. However, in this study, the intensity of anticoagulation was set to yield an INR of up to 4.5. In a more recent study,9
the risk of warfarin-related bleeding was found to be no higher in elderly patients than in younger patients receiving warfarin therapy at therapeutic intensity. When the intensity of treatment is controlled and is therapeutic, the treatment is both effective and safe for the elderly. In addition, the study dispels another myth surrounding the issue of anticoagulant treatment in the elderly—that the management of therapy is more difficult in that population. At least up to the age of 80 years, elderly patients receiving treatment with warfarin require no more frequent monitoring or dosage adjustment than do younger patients.
Another recent study10
addressed the practice of physicians who prescribe anticoagulation therapy in nursing homes. It was found that although only 19 percent of physicians think that risks “outweigh benefits,” the rest believe that the benefits do not “greatly outweigh the risks” (47 percent) or only “slightly outweigh the risks” (34 percent). In fact, nursing home patients have a potential to benefit the most from stroke prevention since they are burdened by the highest rate of risk factors for stroke. Denial of effective stroke prevention measures for this group of patients would be a grave mistake. The study cites that the excessive risk of falling (71 percent) and a history of gastrointestinal bleeding (71 percent) are the most common reasons for not using warfarin therapy. Neither of these conditons, however, represents an absolute contraindication to anticoagulation. The absolute contraindications are few—active bleeding and noncompliance. There are many relative contraindications to anticoagulation, and these are more likely to be found in the nursing home population. Examples include severe liver disease, uncontrolled hypertension, aortic aneurysm, recent neurosurgery or neurologic hemorrhage within the past two years.
The decision to treat with warfarin should be based on careful consideration of the individual's benefit and risk from therapy, rather than on age itself. Nonetheless, almost one third of physicians surveyed in this study10
believed that a 94-year-old nursing home resident with atrial fibrillation, ischemic heart disease and compensated congestive heart failure should not be offered warfarin treatment because of the patient's “advanced age.” A minority of physicians thought that despite the lack of evidence of falls in the past and the patient's independence in activities of daily living, the mere potential risk of falling should contraindicate treatment with warfarin.
An approach to patient care that minimizes the risk of falling and maximizes safety precautions against injury related to gait disturbances can be much more effectively implemented in nursing homes than within the community-dwelling elderly. Nursing homes may offer an environment that allows close monitoring of a patient's status and intensity of therapy. It is much easier to make sure, for example, that no over-the-counter medications, particularly aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), are taken. When use of an NSAID is unavoidable, misoprostol can be added to the medical regimen. These measures likely diminish the risk of gastrointestinal bleeding in patients treated with warfarin, even if they have a history of bleeding.11
Finally, warfarin treatment should be discussed with patients and their families. Advanced age should no longer be considered a contraindication for anticoagulation. In addition, the fact that the patient is residing in a nursing home also should not adversely influence the decision to use anticoagulation.