Correction of Warfarin Coagulopathy for Non-bleeding Patients in the Outpatient Setting at an Ambulatory Care Organization: Application of Vitamin K Guidance.

Background: Warfarin is an effective anticoagulant but requires close International Normalized Ratio (INR) monitoring and may occasionally require correction of excessive anticoagulation. Current guidelines provide limited practical guidance on the administration of vitamin K for the management of supratherapeutic INR levels ≥ 5.0 in non-bleeding outpatients.

Objective: Based on expert consensus and guidelines, the Atrius Health Anticoagulation Management Services (AMS) has developed internal guidance for oral vitamin K use in highly selected populations. This study will describe the internal guidance for oral vitamin K use and present associated results and clinical outcomes.

Methods: Episodes with INR > 5.0 were included, with vitamin K considered for episodes with INR ≥ 6. Moreover, compelling indications and exclusions to select ideal patients for vitamin K intervention were also defined.

Results: Overall, episodes were managed conservatively; of the 246 collected episodes of excessive anticoagulation, in 18 episodes (7%), patients received vitamin K, and in 228 (93%) episodes, patients did not receive vitamin K. The mean index INR was 6.0 (range 5.0 - 10.5, SD 1.07), with nearly 57% of episodes achieving INR correction and 15% of episodes developing INR overcorrection. High thrombotic risk patients, regardless of hemorrhagic risk, were less likely to receive vitamin K. Three episodes (1.2%) resulted in bleeding complications. No thrombotic complications occurred during the 30-day follow-up of the index INR value ≥ 5.0.

Conclusion: Our internal guidance is a novel, standardized approach that serves as a decision support tool for the management of warfarin-associated coagulopathy and vitamin K intervention using patient-specific characteristics and index INR values. This guidance may assist other anticoagulation management services with practical applications and require validation in a prospective clinical trial.