Warfarin > aspirin in preventing strokes in pts older than 75 with A fib (BAFTA)

Clinical Question

In patients older than 75 years with atrial fibrillation, is warfarin more effective than aspirin at preventing strokes?

Bottom Line

This study confirms that warfarin titrated to a target international normalized ratio (INR) of 2.0 to 3.0 is more effective than 75 mg aspirin in preventing strokes without significantly increasing the risk of bleeding complications. (LOE = 1b-)

Reference

Mant J, Hobbs FD, Fletcher K, et al, for the BAFTA investigators; Midland Research Practices Network (MidReC). Warfarin versus aspirin for stroke prevention in an elderly community population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged Study, BAFTA): a randomised controlled trial. Lancet 2007;370:493-503.  [PMID:17693178]

Study Design

Randomized controlled trial (single-blinded)

Funding

Government

Allocation

Uncertain

Setting

Outpatient (primary care)

Synopsis

This trial was an open-label trial with masked assessment of the outcomes. The patients, who were at least 75 years of age with atrial fibrillation or atrial flutter, were recruited from primary care practice. They were randomly assigned to receive aspirin (75 mg daily; n = 485) or warfarin (target INR = 2.0 - 3.0; n = 488). The researchers excluded patients with rheumatic heart disease, major hemorrhage within the previous 5 years, intracranial hemorrhage, proven peptic ulcer disease in the previous year, esophageal varices, allergy, terminal illness, recent surgery, or blood pressure higher than 180/110 mm Hg. The researchers used an intention-to-treat analysis to assess the outcomes. The 2 groups were similar at baseline and the researchers evaluated them for an average of 2.7 years. The annual rate of strokes in the warfarin group was 1.6% compared with 3.4% in the aspirin group (number needed to treat [NNT] = 56 per year; 95% CI, 40 - 294). The annual rate of total events (stroke, systemic emboli, intracranial hemorrhage including subdural hematoma) in each group was 1.8% and 3.8%, respectively (NNT = 51; 37 - 290). There was no significant difference between the 2 groups in the rate of extracranial hemorrhage (1.4% and 1.6%). The authors accounted for 100% of the patients at the end of the study.