Practical Challenges in the Management of Oral Anticoagulation

Steven R. Kayser, PharmD

Disclosures

Prog Cardiovasc Nurs. 2005;20(2):80-85. 

In This Article

Therapeutic Goal and Duration of Therapy

One of the most significant advances in anticoagulant management with warfarin is the confirmation that lower intensity of therapy is effective and, most importantly, associated with a lower incidence of bleeding. An INR of 2-3 is appropriate for most conditions,[6] with the exception of prosthetic valves in the mitral position, recurrent thrombosis, or conditions associated with additional risk factors (e.g., AF plus the presence of a prosthetic aortic valve).[14]

Studies of lower intensity warfarin (INR <2) for certain conditions have been controversial.[15,16] Some investigators have shown that following 6 months of conventional control with an INR of 2-3, long-term therapy with a goal of 1.5-2 resulted in a continued decrease in recurrence of venous thromboembolism compared with no anticoagulation. Others have shown that maintenance of the INR with a goal of 2-3 resulted in a greater decrease in recurrence without an increase in bleeding. As a result, most clinicians will aim for a minimum INR of 2.[6] It is important when counseling patients to stress that the therapeutic range is 2-3, and that it is normal for there to be some fluctuation, and that it is rare that the INR will be the same at each clinic visit.

The duration of therapy is more controversial. Conditions associated with an identified provocable cause for a clot may only require treatment for 6 months, assuming the cause is no longer present. Examples include trauma, surgery, or immobilization that is no longer present. If there is a persistent condition (e.g., cancer) or if the thrombosis is unprovoked, therapy should be continued for a longer period of time—perhaps for a lifetime. Evaluation for either an inherited or acquired thrombophilia (Factor V Leiden or prothrombin G20210A) may be appropriate depending upon the clinical scenario, age of occurrence, and family history.[17]

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