Outcomes and predictors of very stable INR control during chronic anticoagulation therapy

Area of Science:

• Pharmacology and Therapeutics
• Clinical Medicine
• Cardiology

Background:

• Traditional warfarin management recommends International Normalized Ratio (INR) monitoring every 4 weeks.
• Stable INR control may allow for less frequent monitoring in certain patient populations.
• Identifying predictors of stable INR is crucial for optimizing anticoagulation therapy.

Purpose of the Study:

• To identify patients with stable INR control on warfarin therapy.
• To compare thromboembolism, bleeding, and death rates between stable and comparator patients.
• To determine independent predictors of stable INR control.

Main Methods:

• Retrospective, longitudinal cohort study.
• Patients categorized as 'stable' (all INR values within range) or 'comparator' (at least one INR outside range).
• Multivariate logistic regression used to identify predictors of stable INR.

Main Results:

• 2504 stable and 3569 comparator patients included.
• Combined bleeding and thromboembolism rates were significantly lower in stable patients.
• Independent predictors of stable INR control included age >70 years and absence of heart failure and diabetes.
• Stable patients were less likely to have a target INR ≥3.0 or chronic diseases.

Conclusions:

• Many patients with stable INR control may be safely monitored with intervals longer than 4 weeks.
• Age and absence of specific comorbidities are associated with stable INR control.
• Findings support re-evaluating traditional INR monitoring frequency for select stable patients.