Clinical Health Updates

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.

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.

Study Design:
Randomized controlled trial (single-blinded)

Anticoagulants are more effective than antiplatelet agents at reducing stroke risk in patients with atrial fibrillation, but whether this benefit outweighs the increased risk of bleeding in elderly patients is unknown. The investigators assessed whether warfarin reduced risk of major stroke, arterial embolism, or other intracranial haemorrhage compared with aspirin in elderly patients. 973 patients aged 75 years or over (mean age 81.5 years, SD 4.2) with atrial fibrillation were recruited from primary care and randomly assigned to warfarin (target international normalised ratio 2-3) or aspirin (75 mg per day). Follow-up was for a mean of 2.7 years (SD 1.2). The primary endpoint was fatal or disabling stroke (ischaemic or haemorrhagic), intracranial haemorrhage, or clinically significant arterial embolism. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN89345269. There were 24 primary events (21 strokes, two other intracranial haemorrhages, and one systemic embolus) in people assigned to warfarin and 48 primary events (44 strokes, one other intracranial haemorrhage, and three systemic emboli) in people assigned to aspirin (yearly risk 1.8%vs 3.8%, relative risk 0.48, 95% CI 0.28-0.80, p=0.003; absolute yearly risk reduction 2%, 95% CI 0.7-3.2). Yearly risk of extracranial haemorrhage was 1.4% (warfarin) versus 1.6% (aspirin) (relative risk 0.87, 0.43-1.73; absolute risk reduction 0.2%, -0.7 to 1.2).