Using highly variable warfarin dosing to identify patients at risk for adverse events

Area of Science:

• Pharmacology
• Clinical Medicine
• Health Informatics

Background:

• High variability in warfarin dosing poses risks for anticoagulation control and adverse events.
• A validated system to identify patients with significant dose variability is currently lacking.
• This study aimed to develop and validate a measure for identifying patients with high warfarin dose variability.

Purpose of the Study:

• To develop a scoring system to identify patients with high warfarin dose variability.
• To validate this measure by assessing its correlation with poor anticoagulation control and adverse events.

Main Methods:

• Utilized a database of over 4,000 patients on oral anticoagulation.
• Identified 109 patients with highest dose variability (cases) using coefficient of variation (CoV) and matched them with controls.
• Performed multivariable analysis to identify independent predictors of high CoV and compared anticoagulation control (TTR) and adverse event rates.

Main Results:

• Coefficient of variation (CoV) correlated with anticoagulation control; Time in Therapeutic Range (TTR) was significantly lower in cases (53%) vs. controls (79%).
• High CoV predicted adverse events, with more major hemorrhages and thromboembolic events in cases.
• Independent predictors of high dose variability included hospitalization, decreased oral intake, and use of systemic steroids, acetaminophen, and antibiotics.

Conclusions:

• Coefficient of variation (CoV) effectively identifies patients at risk for poor anticoagulation control and adverse events.
• This novel measure can potentially identify high-risk patients before adverse events occur, improving patient safety.