After a median follow-up of 28.9 months , the median overall survival was 13.6 months longer with ADT plus docetaxel ( combination therapy ) than with ADT alone ( 57.6 months vs. 44.0 months ; hazard ratio for death in the combination group , 0.61 ; 95 % confidence interval [ CI ] , 0.47 to 0.80 ; P < 0.001 ) .