Off-pump ( n = 1472 ) vs on-pump ( n = 1460 ) CABG surgery reduced the risk of acute kidney injury ( 17.5 % vs 20.8 % , respectively ; relative risk , 0.83 [ 95 % CI , 0.72-0 .97 ] , P = .01 ) ; however , there was no significant difference between the 2 groups in the loss of kidney function at 1 year ( 17.1 % vs 15.3 % , respectively ; relative risk , 1.10 [ 95 % CI , 0.95-1 .29 ] , P = .23 ) .