Compared to aspirin , clopidogrel was associated with a lower occurrence of future MACE ( HR = 0.54 , 95 % CI 0.43 to 0.68 , p < 0.001 , number needed to treat : 8 ) and recurrent stroke ( HR = 0.54 , 95 % CI 0.42 to 0.69 , p < 0.001 , number needed to treat : 9 ) after adjustment of relevant covariates .