Table 2. Univariate and multivariate Cox proportional hazards analysis.

Patient characteristics	Univariate analysis		Multivariate analysis
	HR (95%CI)	p value	HR (95%CI)	p value
Race		0.077		–
White	Reference		–	–
Black	1.251 (0.811–1.931)	0.311	–	–
Other	0.502 (0.248–1.019)	0.056	–	–
Age		<0.001	1.032 (1.017–1.048)	<0.001
Sex		0.257		–
Male	Reference		–	–
Female	0.855 (0.652–1.121)		–	–
Grade		<0.001		0.248
Well differetiated	Reference		Reference
Moderately differetiated	0.776 (0.181–3.322)	0.733	2.179 (0.404–11.756)	0.365
Poorly differetiated	0.994 (0.245–4.033)	0.993	1.894 (0.369–9.712)	0.444
Undifferetiated	1.748 (0.375–8.139)	0.477	4.198 (0.689–25.591)	0.120
Unknown	2.291 (0.537–9.421)	0.251	2.101 (0.401–10.988)	0.379
AJCC 8thT stage		<0.001		<0.001
T1	Reference		Reference
T2	1.052 (0.735–1.507)	0.780	1.240 (0.856–1.797)	0.256
T3	1.909 (1.274–2.862)	0.002	1.935 (1.257–2.980)	0.003
T4	2.689 (1.879–3.849)	<0.001	2.364 (1.559–3.585)	<0.001
AJCC 8thN stage		<0.001		0.009
N0	Reference		Reference
N1	1.678 (1.088–2.587)	0.019	1.623 (1.018–2.586)	0.042
N2	3.218 (2.360–4.390)	<0.001	1.905 (1.300–2.792)	0.001
N3	5.013 (2.855–8.804)	<0.001	1.826 (0.951–3.505)	0.071
AJCC 8thM stage		<0.001		<0.001
M0	Reference		Reference
M1	4.253 (3.170–5.704)	<0.001	2.399 (1.695–3.393)	<0.001
Surgery		<0.001		<0.001
Not performed	Reference		Reference
Lobectomy	0.187 (0.136–0.258)	<0.001	0.389 (0.263–0.578)	<0.001
Sublobar resection	0.442 (0.304–0.643)	<0.001	0.889 (0.567–1.394)	0.608
Pneumonectomy	0.384 (0.209–0.706)	<0.001	0.614 (0.317–1.189)	0.148
Radiotherapy		<0.001
No	Reference		Reference
Yes	2.173 (1.631–2.895)	<0.001	1.076 (0.768–1.508)	0.669
Chemotherapy
No	Reference		Reference
Yes	1.423 (1.076–1.882)	0.013	0.725 (0.506–1.039)	0.080

Notes.

*P value for chi-square test. C-index = 0.750.

The total stage was not an independent variable related to T, N, and M stage, therefore it was excluded in the multivariate analysis.