Identifying Warfarin Control With Stroke and Bleed Risk Scores

Area of Science:

• Cardiology
• Pharmacology
• Clinical Medicine

Background:

• Warfarin is crucial for stroke prevention in atrial fibrillation (AF).
• Effective warfarin therapy depends on achieving and maintaining a therapeutic range (TTR).
• Existing stroke and bleed risk scores (CHADS₂, CHA₂DS₂-VASc, HAS-BLED) may predict warfarin control quality.

Purpose of the Study:

• To evaluate if commonly used stroke and bleed risk scores can identify patients with poor warfarin control (low TTR).
• To assess the applicability of these scores across diverse ethnic populations and varying anticoagulation control levels.

Main Methods:

• Retrospective analysis of non-valvular AF patients on warfarin in Australia and Singapore (2014).
• Calculation of Time in Therapeutic Range (TTR) and stroke/bleed risk scores (CHADS₂, CHA₂DS₂-VASc, HAS-BLED).
• Comparison of mean TTR across different risk score categories.

Main Results:

• Mean TTR decreased significantly with increasing HAS-BLED score categories at both sites.
• Higher percentage of patients achieved TTR >65% in lower HAS-BLED categories.
• CHA₂DS₂-VASc showed a significant association with TTR in Singapore but not Australia; CHADS₂ showed no significant association at either site.

Conclusions:

• The HAS-BLED score is the most suitable among the evaluated risk models for identifying patients likely to have poor warfarin control (TTR).
• High HAS-BLED scores may guide prescribers in assessing warfarin suitability and selecting appropriate anticoagulants for AF patients.