Median overall survival was significantly longer in the abiraterone acetate group than in the placebo group ( 34.7 months [ 95 % CI 32.7-36 .8 ] vs 30.3 months [ 28.7-33 .3 ] ; hazard ratio 0.81 [ 95 % CI 0.70-0 .93 ] ; p = 0.0033 ) .