Anticoagulation control and prediction of adverse events in patients with atrial fibrillation: a systematic review

Area of Science:

• Cardiology
• Pharmacology
• Clinical Research

Background:

• Atrial fibrillation patients on oral anticoagulation face risks of bleeding and clotting.
• International Normalized Ratio (INR) control is crucial for managing anticoagulation therapy.
• Previous research has not systematically linked INR control metrics to adverse event prediction.

Purpose of the Study:

• To systematically examine the relationship between INR control measurements and adverse events in atrial fibrillation patients.
• To assess the predictive value of time in therapeutic range (TTR) and percentage of INRs in range for major hemorrhage and thromboembolic events.

Main Methods:

• A systematic literature search was conducted across MEDLINE, EMBASE, and Cochrane databases up to January 2008.
• Included studies focused on atrial fibrillation patients using vitamin-K antagonists, reporting INR control measures (TTR, percentage of INRs in range) and adverse events.
• 47 studies from 38 articles were analyzed, comparing INR control between randomized controlled trials and retrospective studies.

Main Results:

• TTR and percentage of INRs in range were significantly correlated (P<0.001).
• Randomized controlled trials demonstrated better INR control (64.9%) than retrospective studies (56.4%; P=0.01).
• TTR showed a significant negative correlation with major hemorrhage (r=-0.59; P=0.002) and thromboembolic rates (r=-0.59; P=0.01), particularly in retrospective studies.

Conclusions:

• Time in therapeutic range (TTR) and percentage of INRs in range are effective predictors of INR control in atrial fibrillation patients.
• Retrospective study data strongly support TTR's utility in predicting reduced adverse events.
• Improving TTR by 6.9% in retrospective studies correlated with a reduction of 1 major hemorrhage event per 100 patient-years.