Quality of anticoagulation control among patients with atrial fibrillation

Objectives: To assess the level of anticoagulation control achieved in patients with atrial fibrillation (AF) receiving routine medical care within a large managed care organization and to explore patient factors that influence control. Study Design: Retrospective cross-sectional study of all patients with AF treated in Clalit Health Services (CHS) community clinics in central Israel between November 1, 2006, to October 31, 2007. Methods: Using the CHS computerized database, we identified 906 patients with a diagnosis of AF who were treated with warfarin for at least 6 months. Data included patient demographics, comorbidities, and international normalized ratio (INR) values as well as managing physician certification. Anticoagulation control was assessed by measurement of time within therapeutic range (TTR) (INR 2-3). Univariate and multivariate analyses were performed to explore the association of patient variables with anticoagulation control. Results: Roughly two-thirds of patients had poor anticoagulation control, as evidenced by TTR of <60%; the mean TTR was 48.6%. Poor control was significantly associated with female sex, advancing age, and comorbid conditions. Heart failure and having a non-board-certified physician were found to be independent predictors of poor control (odds ratio [OR] = 1.63; 95% confidence interval [CI] = 1.20-2.22; and OR = 1.41; 95% CI, 1.05-1.88, respectively). Conclusions: Quality of anticoagulation in patients with AF receiving routine medical care was suboptimal, with nearly half the time spent outside the therapeutic range. Ways to improve anticoagulation control among patients with AF should be sought.