Bob is a 58-year-old man with hypertension and atrial fibrillation. He uses warfarin for stroke prevention, has his INR checked every four to six weeks, and is almost always in the therapeutic range. He has had no dose changes for six months, and he finds his therapy easy to manage.
Bob has been reading about new drugs for stroke prevention on the internet. His golfing buddy takes one of these drugs and it’s not covered by his insurance. It costs about $3/day, but the cardiologist said it’s better than warfarin. Bob wonders if he should be taking this new drug too. What would you advise?
You might explain to Bob that newer oral anticoagulants (NOACs) offer some benefit in terms of convenience, including that INR tests are not required — but kidney function does need to be checked periodically.
Overall though, NOACs seem to have little advantage for people already doing well on warfarin. Research showed that, for people whose INR results are in the therapeutic range at least 66% of the time, NOACs offer no additional benefit in terms of preventing stroke or major bleeding.
You’ll need to talk to Bob about adherence too. Warfarin has a long half-life and is somewhat “forgiving” of missed doses — one missed dose will usually not lead to a sub-therapeutic level. And of course, we can rely on the INR test to ensure that levels are therapeutic.
Bob should be aware that there’s no reversal agent for the new drugs, and no proven management strategy in the event of a bleed.
- For patients who are doing well on warfarin, there is no evidence to support switching to a NOAC.
INR - international normalized ratio