In recent years, new warfarin-like blood thinners have become available to prevent stroke in patients who have atrial fibrillation (an unusual heart beat). Many doctors & researcher says that the new blood thinners will change the patients with atrial fibrillation are managed. But, are the new drugs really better than warfarin (Coumadin)? Should you switch from warfarin to Pradax (dabigatran), Xarelta (rivaroxaban) or Eliquis (apixaban)?
The Pros & Cons of the New Blood Thinners
The new blood thinners do not require you to monitor your INR. And, the new blood thinners have very few interactions; warfarin interacts with hundreds of medications.
Pradax ($3.50/day), Xarelto ($9.50/day) & Eliquis ($4.00/day) are much more expensive than warfarin ($2.30/day). Warfarin is usually dosed once daily; the others require twice daily dosing.
Note: Only Pradax and warfarin are officially approved for use in patients who have atrial fibrillation. Approvals for Xarelto and Eliquis are on their way, though.
Major stomach bleeding is a side effect of blood thinners. Stomach bleeding is serious; it leads to hospital visits and, sometimes, to death.
Warfarin causes major stomach bleeding in up to 3% of users. Your chances of having this side effect are even higher if you have risk factors:
- high blood pressure (greater than 140/90, or 130/80 if you have diabetes)
- kidney disease
- regular use of NSAIDS (Aleve, Advil or, to a lesser degree, Celebrex)
- age > 65 years
- a history of ulcers
Pradax and Xarelto are slightly more likely to cause serious stomach bleeds than warfarin. On the other hand, Eliquis is touted as a safer medication; it causes major stomach bleeds in 2% of users.
If you have atrial fibrillation, and are taking warfarin, your risk of having a stroke is about 1.6% per year. Pradax, Xarelto and Eliquis don’t improve this number very much. For example, Pradax prevents 5 more strokes for every 1000 patients treated. Interestingly, Pradax therapy, when compared to warfarin, results in 2 more heart attacks for every 1000 patients treated.
Should You Switch?
The power of warfarin to prevent strokes depends on how well your INR remains between 2.0 and 3.0. If you have trouble keeping your INR in that range for more than 75% of the time, consider switching to the new blood thinners. The new drugs don’t require INR monitoring.
If you’re taking warfarin, your risk of having a stroke is only 1.6%. However, your risk is higher if:
- You have heart failure
- You are older than 75
- You have high blood pressure
- You have had a stroke or TIA before
- You are a women
If you have several of these risk factors, the benefit of switching to one of the new blood thinners may be worthwhile for you. Why? Read below:
Patient A is taking warfarin and has zero risk factors for stroke. His chance of having a stroke this year is 1.6%. Switching from warfarin to Eliquis will reduce his chance of having a stroke by 20% (to 1.3% this year).
- The absolute difference between 1.6% and 1.3% is only 0.3%.
Patient B is taking warfarin has several risk factors for stroke. His risk of stroke is 5% this year. If he switches, his chance of having a stroke will go down by 20% to 4% this year.
- The absolute difference between 5% and 4% is 1%.
- Clearly, Patient B benefits a lot more from the switch than Patient A.
Eliquis vs Warfarin Study Conclusion
In patients with atrial fibrillation, apixaban was superior to warfarin in preventing stroke or systemic embolism, caused less bleeding, and resulted in lower mortality. (Funded by Pfizer)