Extended International Normalized Ratio testing intervals for warfarin-treated patients.

Area of Science:

• Pharmacology and Therapeutics
• Clinical Medicine
• Health Services Research

Background:

• Standard warfarin management typically involves International Normalized Ratio (INR) testing every 4 weeks.
• Previous research indicated that stable INR patients could tolerate testing every 12 weeks.

Purpose of the Study:

• To evaluate the implementation and safety of extended INR testing intervals for stable warfarin patients across multiple anticoagulation clinics.
• To assess the impact of extended INR testing on patient outcomes and clinical practice.

Main Methods:

• A multicenter collaborative study involving six anticoagulation clinics from 2014 to 2016.
• Identification of eligible patients based on stable INR values and minimal warfarin dose adjustments.
• Assessment of extended INR testing (>5 weeks) adoption rates and safety outcomes, including INR values, bleeding events, and ED visits.

Main Results:

• Extended INR testing was identified as eligible for 26.5% of warfarin patients (890/3362).
• The utilization of extended INR testing increased significantly from 41.8% to 69.3% during the study period.
• Safety outcomes were comparable, with similar rates of out-of-range INRs and major bleeding events; however, clinically relevant non-major bleeding and ED visits were lower with extended testing.

Conclusions:

• Extended INR testing for stable warfarin patients is feasible and can be successfully implemented in various anticoagulation clinic settings.
• The practice demonstrated safety and effectiveness, supporting less frequent monitoring for select patients.
• This approach can optimize resource allocation and potentially improve patient convenience without compromising safety.