STROKE (ISCHAEMIC) - ASPIRIN DECREASES DEATH AND RECURRENT STROKE.

Clinical Bottom Line: Aspirin, started early in acute ischemic stroke, decreases death and recurrent strokes in the next month.

Appraised by: Straus; 22 September 1997

Clinical Scenario: 85 year old man with Left arm and facial weakness and a history of hypertension

Three-part Question: In a patient with acute ischemic stroke, does treatment with aspirin decrease the risk of death or recurrent stroke? Search Terms: aspirin, stroke in MEDLINE

The Study:
Double-blinded randomised (concealed) controlled trial with intention-to-treat analysis.
Pts in mainland China hospitals were entered if within 48 hrs of onset of symptoms and had no mandatory indications or contraindications to aspirin. Main criterion was responsible physician's uncertainty about whether aspirin was indicated. CT scanning before randomisation (done in 88%; 84% of them showed a lesion) was mandatory only for pts who were comatose (13%). A quarter were over 70, 2/3 were men, 7% had AF. A quarter were entered within 12 hours, and half within 24 hours. 63% were anterior, 30% were lacunar, and 7% posterior.
Control group (N = 10552; 10320 analysed): placebo tablet given for 4 weeks, Chinese herbal products could be added if considered indicated
Experimental group (N = 10554; 10335 analysed): aspirin 160 mg daily for 4 wks, Chinese herbal products could be added if considered indicated

The Evidence:

Outcome	Time to Outcome	CER	EER	RRR	ARR	NNT
death	4 wks	0.039	0.033	15%	0.006	167
	95% Confidence Intervals:			2% to 28%	0.001 to 0.011	90 to 1088
stroke or death	4 wks	0.059	0.053	10%	0.006	167
	95% Confidence Intervals:			0% to 21%	0 to 0.012	NNT 81 to INF; NNH 3692 to INF
major bleed	4 wks	0.006	0.01	-67%	-0.004	-250
	95% Confidence Intervals:			-100% to -26%	-0.006 to -0.002	-637 to -156

Comments:

1. See also International Stroke Trial Collaborative Group. The IST: a randomised trial of aspirin, subcutaneous heparin, both or neither among 19435 patients with acute ischemic stroke. Lancet 1997;349:1569-81.
2. Combining the CAST, IST and the MAST (40397 patients in total) - NNT = 167 to prevent one death, NNT = 100 to prevent one death or nonfatal stroke, NNT = 143 to prevent one recurrent stroke and NNH = 500 to cause one hemorrhagic transformation of the initial stroke. NNT to prevent death or dependence several weeks later was 77.
3. pts in CAST low risk compared with IST patients, younger, and had half the in-hospital mortality, suggesting that CAST may have excluded more severe pts if concerned about hemorrhage.
4. CAST had large numbers of pts using herbal medications, no specified contraindications for aspirin use (left to the discretion of each physician), and no explicit definition of hemorrhagic stroke.

Expiry Date: March/98

References: Chinese acute stroke trial collaborative group. CAST: randomised placebo-controlled trial of early aspirin use in 20000 patients with acute ischaemic stroke. Lancet 1997;349:1641-9.

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