Warfarin Dose Adjustment for Elevated INR

Rationale for Dose Reduction

The American College of Chest Physicians recommends continuing the same dose for single out-of-range INRs only when the deviation is ≤0.5 units from therapeutic range, and since this patient's INR exceeds the therapeutic range by 1.25 units, dose adjustment is warranted rather than simply continuing the current regimen 1
The current INR of 3.25 is significantly above the target range of 1.5-2.0, representing an elevation of more than 1.0 INR units above the upper therapeutic limit 1

Hold warfarin completely for 1-2 doses until INR begins trending toward therapeutic range, according to the American College of Chest Physicians guidelines 1
Reduce the total weekly warfarin dose by 20-30% from the current regimen, as recommended by the European Heart Journal 3

Recheck INR within 1-2 weeks after restarting warfarin at the reduced dose, as recommended by the American College of Chest Physicians and the European Heart Journal 1, 3
Once INR stabilizes in the 1.5-2.0 range, continue monitoring every 1-2 weeks initially, then gradually extend to every 4 weeks if INR remains stable, according to the European Heart Journal 3

Do not make excessive dose reductions: A 50% dose reduction would be too aggressive and likely result in subtherapeutic anticoagulation, as warned by the American College of Chest Physicians 1
Do not administer vitamin K for INR 3.25 without bleeding: Vitamin K is not indicated unless INR exceeds 5.0 without bleeding or there is active bleeding at any INR level, according to the American College of Chest Physicians 1

Identify factors that may have caused INR elevation, such as recent dietary changes, new medications or drug interactions, intercurrent illness affecting warfarin metabolism, alcohol consumption changes, or medication non-adherence, as recommended by the European Heart Journal 3