In high-volume radial centers , the primary outcome was reduced with radial versus femoral access ( hazard ratio [ HR ] : 0.49 ; 95 % confidence interval [ CI ] : 0.28 to 0.87 ) but not in intermediate - ( HR : 1.23 ; 95 % CI : 0.88 to 1.72 ) or low-volume centers ( HR : 0.83 ; 95 % CI : 0.52 to 1.31 ; interaction p = 0.021 ) .