Background-To date, there has been no systematic examination of the relationship between international normalized ratio (INR) control measurements and the prediction of adverse events in patients with atrial fibrillation on oral anticoagulation.
Methods and Results-We searched MEDLINE, EMBASE, and Cochrane through January 2008 for studies of atrial fibrillation patients receiving vitamin-K antagonists that reported INR control measures (percentage of time in therapeutic range [TTR] and percentage of INRs in range) and major hemorrhage and thromboembolic events. In total, 47 studies were included from 38 published articles. TTR ranged from 29% to 75%; percentage of INRs ranged from 34% to 84%. From studies reporting both measures, TTR significantly correlated with percentage of INRs in range (P
Conclusions-In atrial fibrillation patients receiving orally administered anticoagulation treatment, TTR and percentage of INRs in range effectively predict INR control. Data from retrospective studies support the use of TTR to accurately predict reductions in adverse events. (Circ Cardiovasc Qual Outcomes. 2008; 1:84-91.)