Stroke: early aspirin decreased death.

Clinical bottom line (level 1b)

  1. Patients with suspected ischaemic stroke who were given early aspirin were less likely to die than those given placebo (NNT = 186 at 4 weeks) .
  2. Patients given early aspirin had no clear difference in combined death or dependency, than those given placebo.
CAST (Chinese Acute Stroke Trial) Collaborative Group : Lancet 1997; 349: 1641-1649
Expires November 2002

The study

Double-blinded concealed randomised trial with intention-to-treat
Setting: 413 hospitals, China

21106 patients (aged mean 63 years, 63% male) suspected ischaemic stroke within previous 48 hours diagnosed clinically

Excluded if
  • little likelihood of worthwhile benefit from aspirin (eg. minor stroke, concomitant life-threatening illness)
  • risk of adverse effects (eg. recent serious gastrointestinal bleed)


    • Control Group: (n = 10554, 10332 analysed): placebo
    Experimental Group: (n = 10552, 10320 analysed): aspirin 160 mg once daily until discharge or 4 weeks

    98% followed for 4 weeks
    Outcome notes:
    • death : all causes
    • death or dependency : at discharge
    • extracranial bleed : fatal or transfused

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    death 4 weeks 398
    (3.86%)    		 343
    (3.32%)    		 14.0%
    (1.00% to 25.0%)    		 0.54%
    (0.003% to 1.05%)    		 186
    (96 to 3276)
    death or dependency weeks 3266
    (31.7%)    		 3153
    (30.5%)    		 4.00%
    (0.00% to 7.00%)    		 1.14%
    (-0.12% to 2.40%)    		 88
    (NNT = 813 to infinity;
    NNH = 42 to infinity)
    recurrent stroke 4 weeks 351
    (3.40%)    		 335
    (3.25%)    		 5%
    (-10% to 18%)    		 0.16%
    (-0.33% to 0.65%)    		 626
    (NNT = 626 to infinity;
    NNH = 304 to infinity)

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNH
    (95% CI)
    extracranial bleed 4 weeks 58
    (0.56%)    		 85
    (0.83%)    		 -48%
    (-106% to -6%)    		 -0.27%
    (-0.50% to -0.04%)    		 370
    (201 to 2320)

    Comments

    1. There were no differences between the baseline characteristics of both groups.
    2. No patients received thrombolytic therapies, and median time to aspirin was 25h post-onset of symptoms. This may have reduced the degree of benefit.

    Citation

    1. CAST (Chinese Acute Stroke Trial) Collaborative Group , : CAST: randomised placebo-controlled trial of early aspirin use in 20 000 patients with acute ischaemic stroke. Lancet 1997; 349: 1641-1649
    Search Terms: stroke in Cochrane
    Contributor: Nick Shenker and Clare Wotton, November 1999
    Reviewer: Terry Shaneyfelt

    Clinical Question.
    Patient acute ischaemic stroke
    Intervention or Exposure early aspirin
    Comparison placebo
    Outcome death and dependency