Over a median period of 12 months , the long detection period was associated with a 25 % reduction in the number of overall therapies ( 115.6 versus 86.8 per 100 patient-years ; incidence rate ratio , 0.75 ; 95 % confidence interval , 0.61-0 .93 ; P = 0.008 ) and a 34 % reduction in the number of shocks ( rate per 100 patient-years , 51.2 versus 38.1 ; incidence rate ratio , 0.66 ; 95 % confidence interval , 0.48-0 .89 ; P = 0.007 ) .