Primary prevention of arterial thromboembolism in non-rheumatic atrial fibrillation in primary care: randomised controlled trial comparing two intensities of coumarin with aspirin

Objective To investigate the effectiveness of aspirin and coumarin in preventing thromboembolism in patients with non-rheumatic atrial fibrillation in general practice. Design Randomised controlled trial. Participants 729 patients aged greater than or equal to 60 pars with atrial fibrillation, recruited in general practice, who had no established indication for coumarin. Mean age was 75 years and mean follow up 2.7 years. Setting Primary care in the Netherlands. Interventions Patients eligible for standard intensity coumarin (international normalised ratio 2.5-3.5) were randomly assigned to standard anticoagulation, very low intensity coumarin (international normalised ratio 1.1-1.6), or aspirin (150 mg/day) (stratum 1). Patients ineligible for standard anticoagulation were randomly assigned to low anticoagulation or aspirin (stratum 2). Main outcome measures Strike, systemic embolism, major haemorrhage, and vascular death. Results 108 primary events occurred (annual event rate 5.5%), including 13 major haemorrhages (0.7% a year), The hazard ratio was 0.91 (0.61 to 1.36) for low anticoagulation versus aspirin and 0.78 (0.34 to 1.81) for standard anticoagulation versus aspirin. Non-vascular death it as less common in die low anticoagulation Ir;roup than in die aspirin group (0.41, 0.20 to 0.82). There nas no significant difference between the treatment groups in bleeding incidence, High systolic and lo iv diastolic blood pressure and age were independent prognostic Factors. Conclusion In a general practice population (without established indications for coumarin) neither low nor standard intensity anticoagulation is better than aspirin in preventing primary outcome events. Aspirin may therefore be the first choice in patients with atrial fibrillation in general practice.