Table 4.

Marginal Effects of Adjusted Hazard Model Estimates of the Impact of Provider Quartile of Volume on Patient Mortality at Select Time Points for Patients Undergoing Isolated CABG in Taiwan 1998–2007

Outcome	1-Month Mortality				3-Month Mortality				6-Month Mortality				12-Month Mortality
Overall	Mean Mortality=0.058				Mean Mortality=0.091				Mean Mortality=0.112				Mean Mortality=.0135
among Surgeons in the Lowest Volume Quartile (reference group)	Mean Mortality=0.091				Mean Mortality=0.144				Mean Mortality=0.178				Mean Mortality=0.208
among Hospitals in the Lowest Volume Quartile (reference group)	Mean Mortality=0.090				Mean Mortality=0.132				Mean Mortality=0.158				Mean Mortality=0.185
	Marginal Effect	p-value	Marginal Effect	p-value	Marginal Effect	p-value	Marginal Effect	p-value	Marginal Effect	p-value	Marginal Effect	p-value	Marginal Effect	p-value	Marginal Effect	p-value
Surgeon volume quartiles
2nd	−0.012	<.001	−0.057	<.001	−0.015	<.001	−0.031	<.001	−0.018	<.001	−0.013	<.001	−0.023	<.001	−0.003	.003
3rd	−0.017	<.001	−0.089	<.001	−0.021	<.001	−0.051	<.001	−0.026	<.001	−0.022	<.001	−0.033	<.001	−0.005	.003
4th	−0.013	<.001	−0.063	<.001	−0.017	<.001	−0.035	<.001	−0.021	<.001	−0.015	<.001	−0.026	<.001	−0.003	.008
Hospital volume quartiles
2nd	−0.005	.008	−0.007	.489	−0.005	.054	−0.004	.492	−0.007	.008	−0.002	.498	−0.009	.008	0.000	.510
3rd	−0.004	.055	−0.009	.439	−0.006	.008	−0.005	.444	−0.006	.053	−0.002	.451	−0.007	.054	0.000	.467
4th	−0.010	<.001	−0.042	<.001	−0.013	<.001	−0.023	<.001	−0.016	<.001	−0.010	.006	−0.019	<.001	−0.002	.029
Controlling for unobserved heterogeneity?	No		Yes		No		Yes		No		Yes		No		Yes

CABG, coronary artery bypass grafting.