Table 2.

The results of univariate and multivariate Cox regression analyses.

Variable	Univariate		P value	Multivariate		P value
	HR	95%CI		HR	95%CI
Age
50-60	Reference			Reference
60-75	1.37	1.20-1.57	<0.001	1.40	1.22-1.62	<0.001
>75	2.56	2.19-3.00	<0.001	2.38	2.02-2.80	<0.001
Race
Black	Reference			Reference
White	0.52	0.36-0.75	0.025	0.89	0.67-1.25	0.453
Other	0.78	0.47-1.28	0.333	1.01	0.61-1.67	0.671
Sex
F	Reference			Reference
M	1.23	1.09-1.40	0.003	1.21	1.06-1.38	0.003
Thickness
0-1	Reference			Reference
1-2	1.21	1.05-1.47	0.034	1.12	0.85-1.37	0.541
2-4	1.68	1.38-2.04	0.029	1.17	1.05-1.43	0.049
>4	2.78	2.40-3.20	<0.001	1.28	1.12-1.55	<0.001
Ulceration
Yes	Reference			Reference
No	0.44	0.39-0.49	<0.001	0.56	0.49-0.63	<0.001
Number
1	Reference			Reference
>1	0.57	0.48-0.68	<0.001	0.61	0.51-0.73	<0.001
Stage_M a
No
Yes	4.22	3.60-4.95	<0.001	2.95	2.50-3.48	<0.001
Stage_N
N1	Reference			Reference
N2	1.38	1.21-1.58	<0.001	1.27	1.11-1.45	<0.001
N3	2.77	2.40-3.20	<0.001	2.00	1.72-2.32	<0.001
Location
Head and face	Reference			Reference
Trunk	0.89	0.75-1.05	0.172	1.09	0.92-1.29	0.341
Upper limb and shoulder	0.81	0.67-0.98	0.048	0.98	0.81-1.18	0.857
Lower limb and hip	0.89	0.74-1.06	0.202	0.89	0.74-1.08	0.263
Others	1.10	0.76-1.58	0.584	1.22	0.85-1.76	0.272
Surgery
No	Reference			Reference
Yes	0.72	0.63-0.81	<0.001	0.80	0.71-0.91	<0.001

^aAJCC Stages: The eighth edition American Joint Committee on Cancer (AJCC) TNM staging system.