Stroke: anticoagulants are better than aspirin at preventing vascular events.

Clinical bottom line (level 1a)

  1. Patients with nonrheumatic atrial fibrillation and a history of stroke or TIA who are given anticoagulants are less likely to have any vascular event, than those given aspirin (NNT = 9 at 2 years) .
  2. Patients are less likely to have a recurrent stroke (NNT = 8 at 2 years) .
  3. However, major extracranial bleeds are increased (NNH = 33 at 2 years) .
Koudstaal : The Cochrane Library, Oxford: Update Software 2000; 4: -
Expires December 2002

The study

Systematic review of randomised controlled trials of
  • Patients: nonrheumatic atrial fibrillation and a previous transient ischaemic attack or minor ischaemic stroke
  • Intervention: open label oral anticoagulants (INR 2.5 to 4.0) compared with aspirin (300 mg per day)
  • Outcome: all major vascular events (vascular death, recurrent stroke, myocardial infarction, systemic embolism); all fatal and nonfatal recurrent strokes; any intracranial bleed; major extracranial bleed (severe enough to lead to hospitalisation, blood transfusion or surgery)


    • Articles found in not stated using not stated, not stated (search terms: Stroke Group strategy- detailed in text ) and personal contact with trialists

    Selection criteria: as above
    Appraisal criteria: detailed in text
    Articles excluded if:

    one trial involving 455 patients

    The evidence

    Outcome Time to outcome CER OR
    (95% CI)    		 NNT
    (95% CI)
    all vascular events 2 years 70/230
    (30%)    		 0.55
    (0.36 to 0.83)     		9
    (6 to 27)
    recurrent stroke 2 years 52/230
    (23%)    		 0.36
    (0.22 to 0.59)     		8
    (6 to 12)
    major extracranial bleed 2 years 2/230
    (0.87%)    		 4.65
    (1.66 to 12.99)     		-33
    (-180 to -11)

    • There was no clear difference in intracranial bleeding.

    Comments

    1. How reliable is a systematic review with only one trial included? Effectively, just a randomised controlled trial.
    2. The systematic review will probably be repeated in the hope that more studies can be combined.

    Citation

    1. Koudstaal P, : Anticoagulants versus antiplatelet therapy for preventing stroke in patients with nonrheumatic atrial fibrillation and a history of stroke or transient ischemic attacks (Cochrane Review). The Cochrane Library, Oxford: Update Software 2000; 4: -
    Contributor: Clare Wotton and Bob Phillips, October 2000
    Reviewer:

    Clinical Question.
    Patient nonrheumatic AF, and stroke or TIA
    Intervention or Exposure anticoagulants
    Comparison antiplatelets
    Outcome recurrent stroke