Table 2.

Univariate analyses of OS and CSS.

Covariable	OS		CSS
	HR (95%CI)	P	HR (95%CI)	P
Age (<65 as ref.)
≥65	2.07 (1.72–2.50)	<0.001	2.01 (1.61–2.50)	<0.001
Gender (male as ref.)
Female	0.86 (0.70–1.05)	0.146	0.79 (0.62–0.999)	0.049
Race (whites as ref.)
Black	0.90 (0.70–1.16)	0.411	0.77 (0.57–1.04)	0.086
Other	0.81 (0.67–0.98)	0.033	0.83 (0.67–1.03)	0.098
Year of diagnosis (1988–2003 as ref.)
2004–2012	0.74 (0.62–0.88)	<0.001	0.75 (0.61–0.92)	0.005
Grade (grade I as ref.)
Grade II	0.65 (0.26–1.61)	0.331	0.53 (0.17–1.64)	0.246
Grade III	0.57 (0.28–1.15)	0.114	0.49 (0.16–1.48)	0.188
Grade IV	0.46 (0.23–0.92)	0.030	0.40 (0.14–1.14)	0.082
Histology (squamous cell carcinoma as ref.)
Non-keratinizing carcinoma/undifferentiated carcinoma	0.71 (0.58–0.86)	<0.001	0.69 (0.56–0.85)	<0.001
Surgery (no surgery as ref.)
Surgery	0.63 (0.47–0.85)	0.002	0.61 (0.43–0.87)	0.006
Radiotherapy (no radiotherapy as ref.)
Radiotherapy	0.50 (0.41–0.60)	<0.001	0.50 (0.41–0.61)	<0.001