Management of Elevated INR in Elderly Patients on Warfarin

Immediate Management Strategy

• Withhold warfarin for 1-2 doses until INR falls back into therapeutic range, and consider adding oral vitamin K 1-2.5 mg for elderly patients with increased bleeding risk factors 1, 2
• Administer oral vitamin K 1-2.5 mg to elderly patients with elevated INR, as recommended by the American College of Cardiology for patients at increased risk of bleeding 1, 2

Recheck INR Timing

• Recheck INR within 24-48 hours after intervention to confirm appropriate reduction, and continue monitoring every 24-48 hours until INR stabilizes in therapeutic range 1, 2

Restarting Warfarin at Reduced Dose

• Restart warfarin at 8mg daily, a 20% reduction from the previous 10mg dose, when INR falls below 3.5, as recommended by the American Geriatrics Society and the American Society of Hematology 1, 2
• Reduce the weekly warfarin dose by 20-30% to prevent recurrence, as recommended by the American Geriatrics Society 1

Critical Investigation Required

• Identify the cause of INR elevation before resuming therapy, including new medications, dietary changes, compliance issues, acute illness, or changes in liver/renal function 1, 3

Common Pitfalls to Avoid

• Do not administer high-dose vitamin K (10 mg), as this can cause warfarin resistance for up to a week and make re-anticoagulation difficult 1
• Do not restart warfarin at the original 10mg dose without dose reduction, as recommended by the American Society of Hematology 2
• Do not use IV vitamin K unless there is active bleeding, due to the risk of anaphylactic reactions 2