The primary end point occurred in 42 patients in the immediate-initiation group ( 1.8 % ; 0.60 events per 100 person-years ) , as compared with 96 patients in the deferred-initiation group ( 4.1 % ; 1.38 events per 100 person-years ) , for a hazard ratio of 0.43 ( 95 % confidence interval [ CI ] , 0.30 to 0.62 ; P < 0.001 ) .