Hierarchical linear model (random intercept model) for OPCAB cost
| Characteristics | Multiplier* (95% CI) | p Value | |
|---|---|---|---|
| Patient characteristics | |||
| Intercept, $ | 31 110 | (29 526 to 32 779) | <0.001 |
| Preoperative LOS (days) (ref ≤3) | |||
| 4–6 | 1.024 | (1.010 to 1.038) | 0.001 |
| 7–9 | 1.058 | (1.034 to 1.063) | <0.001 |
| ≥10 | 1.112 | (1.074 to 1.110) | <0.001 |
| Age (years) (ref <65) | |||
| 65–74 | 1.030 | (1.015 to 1.035) | <0.001 |
| ≥75 | 1.052 | (1.031 to 1.055) | <0.001 |
| Number of anastomotic grafts (ref 1) | |||
| ≥2 | 1.118 | (1.079 to 1.116) | <0.001 |
| Use of IABP (ref no) | |||
| Yes | 1.202 | (1.147 to 1.186) | <0.001 |
| Renal failure with dialysis | 1.190 | (1.136 to 1.177) | <0.001 |
| Renal failure without dialysis | 1.127 | (1.083 to 1.128) | <0.001 |
| Peptic ulcer disease excluding bleeding | 0.981 | (0.970 to 0.999) | 0.037 |
| Liver disease | 1.044 | (1.007 to 1.066) | 0.014 |
| Congestive heart failure | 1.011 | (0.998 to 1.020) | 0.091 |
| Duration of anaesthesia (hours) (ref ≤4) | |||
| 6.5–8 | 1.046 | (1.022 to 1.054) | <0.001 |
| ≥8.5 | 1.135 | (1.088 to 1.135) | <0.001 |
| Hospital characteristics | |||
| Teaching | 1.058 | (1.012 to 1.086) | 0.009 |
| Private not-for-profit ownership | 1.037 | (1.004 to 1.058) | 0.023 |
| Hospital index charge (ref 10:1) | |||
| 7:1 | 1.015 | (0.979 to 1.047) | 0.481 |
| Size (ref ≤449) | |||
| 450–799 | 1.018 | (0.987 to 1.043) | 0.307 |
| ≥800 | 0.991 | (0.952 to 1.036) | 0.732 |
| OPCAB hospital volume (ref ≤14) | |||
| 15–29 | 0.985 | (0.962 to 1.015) | 0.379 |
| 30–59 | 1.008 | (0.975 to 1.039) | 0.700 |
| ≥60 | 0.934 | (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.