Quality of oral anticoagulation in patients with atrial fibrillation: A cross-sectional study in general practice

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Abstract
Objective: To evaluate the quality of management of oral anticoagulation among patients on oral anticoagulation for atrial fibrillation, and to verify the relation between patient performance and the risk of an event due to therapy. Methods: In a retrospective cross-sectional study involving 66 general practices, international normalized ratio (INR) values obtained over a 6-mo period were analysed. All INR values were determined by a single clinical laboratory, and additional medical information was provided by GPs. Results: 395 patients were included in the study, with a mean age of 74±9.6 y. In total, 3111 INR values were obtained. The mean number of tests/month per patient was 2.7±4.3. A total of 49 728 d of therapy was evaluated. Fifty-three per cent of the day values were within 0.5 INR units of the target (and 69% within 0.75 INR units of the target). The incidence rate for major bleeding was 4.4/100 patient years (and 2.9/100 patient years for thromboembolic events). There was a significant relation between patient performance and the presence of an event (p=0.017), with an odds ratio of 2.8 (95% CI 1.3–6.3). Conclusion: The quality of oral anticoagulation in patients with atrial fibrillation is suboptimal. This is significantly related to an increased risk of haemorrhagic events.