Baseline characteristics associated with increased infection risk included chronic lung disease ( hazard ratio [ HR ] : 1.66 ; 95 % confidence interval [ CI ] : 1.21 to 2.26 ) , heart failure ( HR : 1.47 ; 95 % CI : 1.11 to 1.95 ) , and longer surgery ( HR : 1.31 ; 95 % CI : 1.21 to 1.41 ) .