In the buffered crystalloid group , RRT was used in 38 of 1152 patients ( 3.3 % ) compared with 38 of 1110 patients ( 3.4 % ) in the saline group ( absolute difference , -0.1 % [ 95 % CI , -1.6 % to 1.4 % ] ; RR , 0.96 [ 95 % CI , 0.62 to 1.50 ] ; P = .91 ) .