Presented as an oral presentation to the Society for General Internal Medicine, San Francisco, Calif, April 1999.
Prevention of Thromboembolism in Atrial Fibrillation
A Meta-analysis of Trials of Anticoagulants and Antiplatelet Drugs
Article first published online: 1 OCT 2002
Journal of General Internal Medicine
Volume 15, Issue 1, pages 56–67, January 2000
How to Cite
Segal, J. B., McNamara, R. L., Miller, M. R., Kim, N., Goodman, S. N., Powe, N. R., Robinson, K. A., Bass, E. B. and for the Johns Hopkins Evidence-based Practice Center (2000), Prevention of Thromboembolism in Atrial Fibrillation. Journal of General Internal Medicine, 15: 56–67. doi: 10.1046/j.1525-1497.2000.04329.x
- Issue published online: 1 OCT 2002
- Article first published online: 1 OCT 2002
- Cited By
- atrial fibrillation;
OBJECTIVE: Appropriate use of drugs to prevent thromboembolism in patients with atrial fibrillation (AF) involves comparing the patient's risk of stroke and risk of hemorrhage. This review summarizes the evidence regarding the efficacy of these medications.
METHODS: We conducted a meta-analysis of randomized controlled trials of drugs used to prevent thromboembolism in adults with nonpostoperative AF. Articles were identified through the Cochrane Collaboration's CENTRAL database and MEDLINE until May 1998.
MAIN RESULTS: Eleven articles met criteria for inclusion in this review. Warfarin was more efficacious than placebo for primary stroke prevention (aggregate odds ratio [OR] of stroke = 0.30, 95% confidence interval [CI] 0.19, 0.48), with moderate evidence of more major bleeding (OR 1.90; 95% CI 0.89, 4.04). Aspirin was inconclusively more efficacious than placebo for stroke prevention (OR 0.56, 95% CI 0.19, 1.65), with inconclusive evidence regarding more major bleeds (OR 0.81, 95% CI 0.37, 1.77). For primary prevention, assuming a baseline risk of 45 strokes per 1,000 patient-years, warfarin could prevent 30 strokes at the expense of only 6 additional major bleeds. Aspirin could prevent 17 strokes, without increasing major hemorrhage. In direct comparison, there was evidence suggesting fewer strokes among patients on warfarin than among patients on aspirin (aggregate OR 0.64, 95% CI 0.43, 0.96), with only suggestive evidence for more major hemorrhage (OR 1.60, 95% CI 0.77,3.35). However, in younger patients, with a mean age of 65 years, the absolute reduction in stroke rate with warfarin compared with aspirin was low (5.5 per 1,000 person-years) compared with an older group (15 per 1,000 person-years).
CONCLUSION: In general, the evidence strongly supports warfarin for patients with AF at average or greater risk of stroke. Aspirin may prove to be useful in subgroups with a low risk of stroke, although this is not definitively supported by the evidence.