Table 5.

Weighted multivariate analyses using IPTW by PS.

Co-variable	OS		CSS
	HR (95%CI)	P	HR (95%CI)	P
Age (<65 as ref.)
≥65	1.91 (1.57–2.31)	<0.001	1.87 (1.49–2.34)	<0.001
Gender (male as ref.)
Female	0.84 (0.69–1.03)	0.101	0.78 (0.61–0.99)	0.045
Race (whites as ref.)
Black	0.96 (0.74–1.23)	0.731	0.79 (0.58–1.07)	0.121
Other	0.86 (0.71–1.05)	0.143	0.86 (0.69–1.07)	0.173
Year of diagnosis (1988–2003 as ref.)
2004–2012	0.63 (0.53–0.76)	<0.001	0.66 (0.54–0.81)	<0.001
Histology (squamous cell as ref.)
Non-keratinizing carcinoma/undifferentiated carcinoma	0.77 (0.63–0.96)	0.020	0.75 (0.59–0.95)	0.016
Surgery (no surgery as ref.)
Surgery	0.58 (0.43–0.78)	<0.001	0.56 (0.39–0.80)	0.002
Radiotherapy (no radiotherapy as ref.)
Radiotherapy	0.50 (0.41–0.60)	<0.001	0.50 (0.40–0.61)	<0.001