Table 3

Hierarchical linear model (random intercept model) for OPCAB cost

CharacteristicsMultiplier* (95% CI)p Value
Patient characteristics
Intercept, $31 110(29 526 to 32 779)<0.001
Preoperative LOS (days) (ref ≤3)
 4–61.024(1.010 to 1.038)0.001
 7–91.058(1.034 to 1.063)<0.001
 ≥101.112(1.074 to 1.110)<0.001
Age (years) (ref <65)
 65–741.030(1.015 to 1.035)<0.001
 ≥751.052(1.031 to 1.055)<0.001
Number of anastomotic grafts (ref 1)
 ≥21.118(1.079 to 1.116)<0.001
Use of IABP (ref no)
 Yes1.202(1.147 to 1.186)<0.001
Renal failure with dialysis1.190(1.136 to 1.177)<0.001
Renal failure without dialysis1.127(1.083 to 1.128)<0.001
Peptic ulcer disease excluding bleeding0.981(0.970 to 0.999)0.037
Liver disease1.044(1.007 to 1.066)0.014
Congestive heart failure1.011(0.998 to 1.020)0.091
Duration of anaesthesia (hours) (ref ≤4)
 6.5–81.046(1.022 to 1.054)<0.001
 ≥8.51.135(1.088 to 1.135)<0.001
Hospital characteristics
 Teaching1.058(1.012 to 1.086)0.009
 Private not-for-profit ownership1.037(1.004 to 1.058)0.023
Hospital index charge (ref 10:1)
 7:11.015(0.979 to 1.047)0.481
Size (ref ≤449)
 450–7991.018(0.987 to 1.043)0.307
 ≥8000.991(0.952 to 1.036)0.732
OPCAB hospital volume (ref ≤14)
 15–290.985(0.962 to 1.015)0.379
 30–591.008(0.975 to 1.039)0.700
 ≥600.934(0.901 to 0.992)0.024
  • *Exponentiated parameter estimates from a log model.

  • IABP, intra-aortic balloon pumping; LOS, length of stay; OPCAB, off-pump coronary artery bypass grafting.