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 preve nting 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 indica tion 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 (internatio nal normalised ratio 2.5-3.5) were randomly assigned to standard anticoagul ation, very low intensity coumarin (international normalised ratio 1.1-1.6) , or aspirin (150 mg/day) (stratum 1). Patients ineligible for standard ant icoagulation were randomly assigned to low anticoagulation or aspirin (stra tum 2). Main outcome measures Strike, systemic embolism, major haemorrhage, and vas cular 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 di e 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 blee ding incidence, High systolic and lo iv diastolic blood pressure and age we re independent prognostic Factors. Conclusion In a general practice population (without established indication s for coumarin) neither low nor standard intensity anticoagulation is bette r than aspirin in preventing primary outcome events. Aspirin may therefore be the first choice in patients with atrial fibrillation in general practic e.