The message is clear: Warfarin saves money

$700 for therapy vs. $100,000 for stroke care

There is clear evidence in the research literature that getting warfarin to atrial fibrillation (AF) patients saves money. There have been several nationwide studies on how much it costs to treat and prevent stroke. According to Cost Management in Cardiac Care, a sister publication of Drug Utilization Review, it costs about $15,000 to prevent a stroke; the average total cost for a 65-year-old stroke patient in this country is $100,000.

Kevin Kennedy, MHS, senior health care analyst at Las Vegas-based HealthInsight, says, "If you treat 100 AF patients with warfarin, you prevent approximately three strokes." Clinical trials demonstrate that stroke rates in control groups (without warfarin) were 4.5% annually, compared to 1.4% in those taking warfarin.1 "That’s where you get the 3.1% absolute risk reduction," he says.

Stroke costs, risk reduced

A few years ago, researchers in Palo Alto, CA, estimated that acute and annual chronic costs of moderate to severe stroke were $34,200 and $18,000, respectively.2 HealthInsight estimates it costs $700 annually to treat one patient with warfarin. "In Nevada, if we can prevent 74 strokes, that would save more than $2 million in health care costs." The population of Nevada is 2 million, and the cost savings would be much larger if they are extrapolated to a more populous state.

More than 2 million people in this country have AF, especially those over age 65. The risk of stroke in AF patients without coexistent risk factors increases slowly with age, and the annual stroke rate almost doubles between patients under 65 and those over 75 with coexistent risk factors.

The stroke rate of patients with AF is five to six times that of those without AF; 30% of AF patients will have a stroke. Pooled results from five trials show an annual stroke rate of 4.5% in controls vs. 1.4% for warfarin-treated patients — a 68% risk reduction.3 (See bar graph on annual stroke incidence, p. 67.)

As early as 1995, the Agency for Health Care Policy and Research’s Patient Out comes Research Team reported warfarin is effective in preventing stroke in many patients with AF. Yet warfarin is still underutilized in eligible patients, and only 25% receive the therapy. The agency points out that half of the country’s strokes could be avoided through more judicious use of warfarin, resulting in an annual savings of $600 million.4 Warfarin underutilization is avoidable. Education is key because under-use of the drug has been linked to misperceptions about its risks and benefits. Misunderstandings include:

    • Providers may overestimate the risks of bleeding and underestimate the importance of optimal dosing to prevent that complication.

    • Age is perceived to be a contraindication rather than an indication for warfarin.

    • Physicians have concerns regarding patient noncompliance.

    • Prothombin time/International Normalized Ratio (PT/INR) testing is considered complex and time-consuming.5 Warfarin is contraindicated in some AF patients because the blood thinner potentiates bleeding disorders. The drug is contraindicated in any patient with aneurysms, cerebrovascular, or other hemorrhagic tendencies, gastrointestinal bleeding tendencies, or active ulcerations. Factors that increase hemorrhagic risk are:

    • Three or more conditions, including seizures, peptic ulcer disease, liver disease, bleeding tendency, alcohol.

    • INR >4.

    • Highly variable INR.

    • Acute warfarin therapy.

Patients who are senile, alcoholic, or psychotic and have a tendency to fall are not candidates, nor are those with pericarditis, bacterial endocarditis, hepatic or renal insufficiency, or an allergy to warfarin. In patients for whom warfarin is contraindicated, aspirin, while about half as effective as warfarin, has been shown to be of benefit in stroke reduction.

References

1. Laupacis A, Albers G, Dalen J, et al. Antithrombotic therapy in atrial fibrillation. Chest 1995; 8(Suppl):353-359.

2. Gage BF, Cardinalli AB, Albers GW, et al. Cost-effectiveness of warfarin and aspirin for prophylaxis of stroke in patients with nonvalvular atrial fibrillation. JAMA 1995; 274:1,839-1,845.

3. Atrial Fibrillation Investigators. Risk factors for stroke and efficacy of antithrombotic therapy in atrial fibrillation. Arch Intern Med 1994; 154:1,449-1,457.

4. Griffin B, Zeller P, Migdail K, et al. Lifesaving Treat ments to Prevent Stroke Underused. Report. Rockville, MD: Department of Health and Human Services, Agency for Health Care Policy and Research; 1995.

5. The Gallup Organization. Physician Attitudes Toward Stroke Prevention, Treat ment, and Oral Anticoagulation. Survey. Princeton, NJ; April 1996.