Paper-based dosing algorithms for maintenance of warfarin anticoagulation

Area of Science:

• Pharmacology
• Clinical Medicine
• Health Services Research

Background:

• Warfarin therapy requires careful monitoring to maintain International Normalized Ratio (INR) within a therapeutic range.
• Paper-based dosing algorithms offer a potentially low-cost and accessible method for warfarin management.
• Optimizing anticoagulation quality is crucial for balancing efficacy and safety in patients taking warfarin.

Purpose of the Study:

• To evaluate the effectiveness of two paper-based warfarin dosing algorithms in achieving therapeutic anticoagulation.
• To compare the quality of anticoagulation (time in therapeutic range) between two different target INR ranges using these algorithms.

Main Methods:

• A randomized clinical trial involving patients undergoing warfarin therapy.
• Patients were randomized to two groups with different target International Normalized Ratio (INR) ranges (2.1-3.0 and 3.1-4.0).
• Anticoagulation quality was assessed by calculating the percentage of total patient-time spent within, above, and below the target INR range over an average follow-up of 2.7 years.

Main Results:

• For the target INR range of 2.1-3.0, patients spent 71% of total time within the therapeutic range, 11% above, and 19% below.
• For the higher target INR range of 3.1-4.0, patients achieved INRs within the therapeutic range for only 40% of total patient time.
• The algorithms demonstrated varying performance based on the target INR range.

Conclusions:

• Paper-based warfarin dosing algorithms show potential for managing anticoagulation, particularly for the standard 2.1-3.0 INR target.
• The algorithm performance suggests suitability for primary care and research settings due to its ease of use and minimal cost.
• Further optimization may be needed for higher target INR ranges to improve anticoagulation quality.