Table 3.

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.