Results

• there were 939 atherosclerotic events in the clopidogrel group during 17,636 patient-years at risk, an average rate per year of 5.32%
  
  
• there were 1031 events in the aspirin group during 17,519 patient-years risk, an average rate per year of 5.83%
  
  
• the relative risk reduction was 8.7% (95% CI 0.3-16.5) in favour of clopidogrel (p=0.043)
  
  
• there was no significant differences between aspirin and clopidogrel in relation to the risk of death from any cause
  
  
• calculating the number to needed to treat from the CAPRIE trial data, it would be necessary to use clopidogrel instead of aspirin in approximately 200 patients for 1 year to avert one additional major clinical event

The authors concluded that long-term administration of clopidogrel to patients with atherosclerotic vascular disease was more effective than aspirin in reducing the combined risk of ischaemic stroke, myocardial infarction, or vascular death. The overall safety profile of clopidogrel was at least as good as that of medium-dose aspirin.

Reference

1. CAPRIE steering committe (1996). A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). Lancet, 348,1329-1339.