Wednesday, December 21, 2011

Warfarin versus the new oral anticoagulants

This review belongs in the hospitalist's library. It covers the two new agents approved in the U.S. as well as those in the pipeline. It cites a lot of comparative effectiveness research. (Not that comparative effectiveness research is anything new, but that's what it's trendy to call it when there are two or more active treatment arms).

So is warfarin dead? No. This little appreciated perspective is offered:

Warfarin's long, effective half-life of approximately 40 hours, may work to the providers' advantage in a nonadherent patient, Therefore, a degree of nonadherence may have a negligible effect on anticoagulation levels, compared with an anticoagulant with a short half-life.

The lack of a requirement for monitoring may also deny the physician the opportunity for patient education and the earlier detection of problems. It denies the practitioner the ability to tailor the intensity of anticoagulant therapy for patient-specific factors, such as for patients on single or dual antiplatelet therapy, or for those patients with an increased bleeding risk. Lastly, it may make it difficult to determine if the specific therapy has failed. If a patient develops a thromboembolic event on warfarin, the INR is measured to determine if the event is truly a failure of therapy or whether the patient was subtherapeutic (due to noncompliance or other factors influencing the INR).

And, my suspicion is that the purported safety and ease of use of these new drugs could lead to complacency in heeding renal precautions and other labeling concerns.