Table 2. Univariable analysis and Cox proportional hazards regression analysis.

Characteristic	Univariable analysis P	Selected factors for building the model multivariable analysis
		Hazard ratio	95% CI	P
Age	<0.001			<0.001
<60		1 (reference)
60–70		1.250	1.187–1.316	<0.001
≥70		1.676	1.586–1.770	<0.001
Gender	<0.001
Male		1 (reference)
Female		0.803	0.769–0.839	<0.001
Race	0.008
White		–	–	–
Black		–	–	–
Other		–	–	–
Location	<0.001			0.016
Upper		1 (reference)
Middle		1.025	0.925–1.135	0.640
Lower		1.104	1.055–1.157	<0.001
Other		0.930	1.005–0.904	0.930
Examined lymph node	<0.001			<0.001
0–9		1 (reference)
10–15		0.876	0.831–0.922	<0.001
≥16		0.815	0.771–0.861	<0.001
T stage	<0.001			<0.001
T1		1 (reference)
T2		1.099	1.035–1.167	0.002
T3		1.267	1.181–1.361	<0.001
T4		1.587	1.481–1.700	<0.001
Extent of surgery	<0.001			<0.001
Lobectomy		1 (reference)
Segmentectomy		1.160	0.979–1.376	0.087
Wedge resection		1.401	1.275–1.538	<0.001
Pneumonectomy		1.187	1.106–1.275	<0.001
Differentiation grade	<0.001			<0.001
Grade I		1 (reference)
Grade II		1.156	1.050 to 1.272	0.003
Grade III or IV		1.269	1.154 to 1.396	<0.001
Unknown		1.100	0.977 to 1.238	0.116
Histology	<0.001			0.031
Squamous carcinoma		1 (reference)
Adenocarcinoma		1.027	0.975 to 1.081	0.628
Others		1.093	1.023 to 1.169	0.009
N stage	<0.001			<0.001
N0		1 (reference)
N1		1.400	1.326–1.478	<0.001
N2		1.800	1.710–1.896	<0.001
Radiation	<0.001
Radiation before surgery		–	–	–
Radiation after surgery		–	–	–
No radiation		–	–	–
Others		–	–	–