Stroke prevention: Age alone does not rule out warfarin

,

PURLs

Stroke prevention: Age alone does not rule out warfarin

J Fam Pract. 2007 November;56(11):902-906

By

Sarah-Anne Schumann, MD

References

1. Mant J, Hobbs FD, Fletcher K, et al. Warfarin versus aspirin for stroke prevention in an elderly community population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged Study, BAFTA): a randomised controlled trial. Lancet 2007;370:493-503.

2. Singer DE, Albers GW, Dalen JE, et al. Antithrombotic therapy in atrial fibrillation: The seventh ACCP (American College of Chest Physicians) conference on antithrombotic and thrombolytic therapy. Chest 2004;126:429S-456S.

3. Fuster V, Rydén LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation). J Am Coll Cardiol 2006;48:854-906.

4. Go AS, Hylek EM, Borowsky LH, et al. Warfarin use among ambulatory patients with non-valvular atrial fibrillation: The Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) study. Ann Intern Med 1999;131:927.-

5. Hart RG, Pearce LA, Aguilar MI. Meta-analysis: Antithrombotic therapy to prevent stroke in patients who have non-valvular atrial fibrillation. Ann Intern Med 2007;146:857-867.

6. Hylek EM, Evans-Molina C, Shea C, et al. Major hemorrhage and tolerability of warfarin in the first year of therapy among elderly patients with atrial fibrillation. Circulation 2007;115:2689-2696.

7. POEM: Bleeding risk with warfarin is high among the elderly. J Fam Pract 2007;6:709.-

8. Garcia D, Hylek E. Stroke prevention in elderly patients with atrial fibrillation. Lancet 2007;370:460-461.

9. Perez-Gomez F, Alegria E, Bejon J, et al. Comparative effects of antiplatelet, anticoagulant, or combined therapy in patients with valvular and non-valvular atrial fibrillation: a randomized multicenter study. J Am Coll Cardiol 2004;44:1557-1556.

10. Rash A, Downes T, Portner R, et al. A randomized controlled trial of warfarin versus aspirin for stroke preventions in octogenarians with atrial fibrillation (WASPO). Age Ageing 2007;36:151-156.

11. Gullov AL, Koeford BG, Petersen P, et al. Fixed minidose warfarin and aspirin alone and in combination vs adjusted-dose warfarin for stroke prevention in atrial fibrillation. Arch Intern Med 1998;158:1513-1521.

12. Witt DM, Sadler MA, Shanahan RL, et al. Effect of a centralized clinical pharmacy anticoagulation service on outcomes of anticoagulation therapy. Chest 2005;127:1515-1522.

13. Wurster M, Doran T. Anticoagulation management: a new approach. Disease Management 2006;9:201-209.

14. Dorfman DM, Goonan EM, Boutilier MK, et al. Point-of-care (POC) versus central laboratory instrumentation for monitoring oral anticoagulation. Vasc Med 2005;10:23-27.

Practice changer

Warfarin is as safe as aspirin and more effective for stroke prevention in elders with atrial fibrillation

Strength of recommendation (SOR)

A: Well-designed randomized controlled trial of elderly patients in the primary care setting, consistent with findings from prior RCTs

Mant et al. Warfarin versus aspirin for stroke prevention in an elderly community population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged Study [BAFTA]): a randomised controlled trial. Lancet 2007;370:493–503.¹

Illustrative Case

An 85-year-old woman with hypertension and chronic atrial fibrillation has transferred her care to you. She takes an aspirin a day for cardiovascular prevention. You know that warfarin is better than aspirin for preventing stroke but worry about the increased risk of bleeding with warfarin.

Should you recommend that she stay on aspirin or switch to warfarin?

Background: BAFTA: A realistic study

We have been reluctant to use warfarin in elders with atrial fibrillation for good reason: risk of hemorrhage. Since there are few trials looking at use of warfarin among elders in primary care settings, we are uncertain about the balance of benefits and harms.

FAST TRACK

Seriously consider warfarin therapy for most of your elderly patients with atrial fibrillation

The BAFTA study¹ is the first trial to compare outcomes of warfarin vs aspirin in elders specifically, in the less-than-ideal conditions of real life.

Guidelines mirror uncertainties

This uncertainty is reflected even in guidelines for anticoagulation in elderly patients with atrial fibrillation.

The 2004 American College of Chest Physicians Seventh Conference on Antithrombotic and Thrombolytic Therapy recommends treating all patients with atrial fibrillation and high risk of stroke with warfarin. Their definition of high-risk includes any patient with 1 or more of the following risk factors: age >75 years, prior ischemic stroke, transient ischemic attack or systemic embolism, congestive heart failure, impaired left ventricular systolic function, hypertension, or diabetes mellitus.²
In contrast, the 2006 guidelines for the management of patients with atrial fibrillation from the American College of Cardiology, American Heart Association, and European Society of Cardiology, are more conservative. They recommend that patients with more than 1 risk factor take warfarin, and patients with only 1 risk factor (for example, a patient older than 75 years of age with no other risk factors) take either warfarin or aspirin.³

Clinical context: Reasonable concerns

Fewer than half of the 10% to 12% of people older than 75 with atrial fibrillation are taking warfarin for stroke prevention. In one study, only 35% of patients 85 years and older with no known contraindication to anticoagulation received warfarin.⁴ Possible reasons for this low rate include:

cost of monitoring warfarin
concerns about compliance
increased risk of hemorrhage
prior studies focused on younger patients, in closely monitored settings.

These factors lead us to speculate that many physicians believe that the risks of warfarin in elderly patients in primary care settings outweigh any potential benefit.

We think this study demonstrates that we should seriously discuss and consider warfarin therapy for most of our elderly patients with atrial fibrillation.

Age alone does not preclude warfarin

The key finding from the BAFTA study is that advanced age alone is not a contraindication to the use of warfarin for stroke prevention in elderly patients with atrial fibrillation

Study summary: Primary care setting, elders only

This prospective randomized open-label trial was designed to test the effectiveness and safety of warfarin vs aspirin in the elderly, in a realistic primary care setting. The study compared the frequency of stroke, intracranial hemorrhage, and other significant arterial embolism in patients taking either warfarin or aspirin.

FAST TRACK

Warfarin was superior to aspirin in all subgroups, including patients over the age of 85

Inclusion criteria. Patients were at least 75 years old (average 81.5 years) with an ECG within the previous 2 years showing atrial fibrillation or atrial flutter. Seventy percent of the patients had been previously diagnosed with atrial fibrillation and 30% were identified because they had an irregular pulse on exam.