When Should Seniors Take Warfarin [Coumadin]?

What is Warfarin (also called Coumadin)?

It is a “blood thinner”, meaning blood will not clot as quickly.


When is it Prescribed?
For Prevention: To prevent blood clots for people with long term high risk problems, such as Atrial Fibrillation (AF)—which is an irregular heartbeat—or an artificial heart valve or who have had repeated blood clots. It.s also for those with some short term conditions, such as after knee or hip replacements, and patients who have had certain types of heart attacks.

For Treatment: For patients with a blood clot, usually in their legs or lungs, because it helps stop extension of the clot until the body can repair the damage.

Are there Risks for Seniors?
For anyone taking the drug there is an increased risk of bleeding (such as from the stomach, bowel or bladder, or into the brain from a head injury). In the under 75 age group, this risk is outweighed by the benefit provided by reducing the risk of a stroke or a clot to the lung.

For those over 75 years, that benefit may be lost because:

1) older seniors are more sensitive to all drugs, to drug interactions, and to their side-effects;

2) they are at greater risk of falling and having a head injury;

3) they have an increasing risk of Cerebral Amyloid Angiopathy (CAA), especially after age 80 when the incidence of CAA may be as high as 50% (meaning every other person has it). CAA is a hardening of the arteries in the brain which makes the vessels more likely to rupture spontaneously or with minimal trauma. And if one is unsteady, tends to fall easily, or has Alzheimer.s Disease, the risk of bleeding may be 33% (meaning one in three may have significant bleeding into the brain).

If you have Atrial Fibrillation (AF), What are the Risks of having a Stroke?
A common reason to take warfarin is to prevent a stroke from AF (an irregular heartbeat which can allow a clot to form within the heart and travel to the brain). However, the risks of having a stroke depend on how many risk factors you have, in addition to the AF. The more risk factors, the greater the risk.

These Risk Factors (RF) are:

. congestive heart failure;
. hypertension (systolic blood pressure >160);
. age over 75;
. diabetes;
. previous stroke or TIA (“mini-stroke”).

Risk of having a stroke if you have AF and take no treatment, increases with more Risk factors:

0 RF: less than 2% risk of a stroke (less than 2 per 100 with AF per year)

1-2 RF: 3-4% per year

3-5 RF: 5-18% per year

(If you do not have AF, the average risk is 0.9% – meaning less than 1 per 100 per year will have a stroke. But, this risk increases just with age: 80 year olds have a 2% risk, meaning 2 out of 100 will have a risk each year.)

Risk of having a stroke if you take aspirin: Aspirin reduces your risk by about 1%. So if your risk is 2%, it will reduce it to 1% (the same as everyone without AF). If your risk is 5%, it will reduce it to 4%, meaning instead of 5 people in 100 having a stroke, four will.

Risk of having a stroke if you take warfarin: Warfarin reduces your risk by about 2-3% (the variation is due to different findings among studies). (It cannot take the risk below the population average however.) If your risk if 5%, it will reduce it to 2%.

What should you do? If you have Atrial Fibrillation, first count your risk factors.
1. If you have none, your risk is already low and aspirin reduces your risk to the same as the average person without AF. Warfarin will also reduce the risk, but increases the bleeding risk by 2% and its benefit may be lost.

2. If you have one or two RF, then your risk rises to 3or 4% and there is debate whether aspirin or warfarin is best, and therefore the decision will depend on your risk of falling and bleeding (for example, if you have a history of stomach ulcer bleeds, you may want to avoid warfarin).

3. With three or more RF, your risk is over 5%, and warfarin will reduce that by 2 in 100 but also carries the risk of more bleeding into the brain (up to 13 per 100 per year over age 80). No treatment eliminates completely the risk of a stroke.

Should You Take Warfarin?

As with any treatment or drug, you must balance risks and benefits, including: the costs of each drug and related testing; your remaining life expectancy (you can expect, on average, to live another 17 years at 65; 11 years at 75; 6 years at 85); side-effects from the drug; other health problems you may have. For some people, having a stroke may be the worst thing that could happen to them because they may become dependent on someone else and therefore they will do anything to avoid a stroke. For others, they may have other priorities and are skeptical about the recommendations because there is a lot of debate about what.s best, and are willing to take their chances by not taking another drug. Also, you may look at it from a more positive angle: if the chance of a stroke is 5%, that also means a 95% chance of not having one!

Based on the research, you might consider NOT taking warfarin long-term, if you have:

1) Only one or two of those risk factors;
2) Poor balance with a tendency to fall;
3) A history of bleeding ulcers or any bleeding disorder;
4) Alzheimer.s Dementia (or any other dementia);
5) An age greater than 75 (and especially greater than 80).

However, if you have three or more major risk factors and don.t have those other problems, then you would most likely benefit from taking warfarin. And remember, this guideline applies only to long-term use of warfarin for treating the heart irregularity atrial fibrillation, not to the short-term treatment of blood clots.

Discuss this with your family and your doctor and then make a decision that.s most comfortable for you at this time of your life.


1. Gage BF. Selecting patients with AFib for anticoagulation. Circulation 2004;110:2287.
2. Rosand J, et al. Warfarin-associated hemorrhage and cerebral amyloid angiopathy: a genetic and pathologic study. Neurology 2000;55:907-8.
3. Bob H. Oral anticoagulation in nursing home residents. JAMDA 2003;Mar/Apr:S50-S51.
4. Van Walraven C, et al. A clinical prediction rule to identify patients with atrial fibrilation and a low risk for stroke while taking aspirin. Arch Intern Med 2003;163:936-43.
5. Hart RG. Stroke prevention in atrial fibrillation. Curr Cardiol Rep 2000;2:51-55.
6. Hart RG, Bailey RD. An assessment of guidelines for prevention of ischemic stroke. Neurology 2002;59:977-82.
7. Albers GW, et al. Antithrombotic and thrombolytic therapy for ischemic stroke. Sixth ACCP consensus conference on antithrombotic therapy. Chest 2001;119:300s-320s.
8. Hirsh J, et al. Am.Heart Assoc./Am.College of Cardiology Foundation Guide to Warfarin Therapy. Circulation.
9. Taylor FC, et al. Systematic review of long term anticoagulation or antiplatelet treatment in patients with non-rheumatic atrial fibrillation. BMJ 2001; 322:321-326.
10. The SPAF III Writing Committee for the Stroke Prevention in Atrial Fibrillation Investigators. JAMA 1998;279.
11. Hylek E, et al. Major hemorrhage & tolerability of Warfarin in the first year of therapy among elderly patients with atrial fibrillation. Circulation 2007;115:2689-96.
12. Mant J, et al. Warfarin versus aspirin for stroke prevention in an elderly community population with atrial fibrillation (BAFTA). Lancet 2007;370:493-503.