Table 2.

Univariate and multivariate analysis for OS of all patients(n = 21,030)

Characteristics	Level	Univariate analysis	Multivariate analysis
		P	HR	95%CI	P
Insurance Recode		< 0.001			< 0.001
	Insured		Reference	Reference	Reference
	No/unknown		1.201	1.152–1.253	< 0.001
Marital status		< 0.001			< 0.001
	Married		Reference	Reference	Reference
	Single		1.140	1.098–1.184	< 0.001
	Unknown		0.985	0.891–1.088	0.760
Age, years		< 0.001			< 0.001
	< 65		Reference	Reference	Reference
	≥65		1.436	1.384–1.489	< 0.001
Race recode		< 0.001			0.508
	White		Reference	Reference	Reference
	Other		1.016	0.970–1.065	0.508
Sex		< 0.001			< 0.001
	Female		Reference	Reference	Reference
	Male		1.106	1.068–1.147	< 0.001
Tumor site		< 0.001			< 0.001
	Pancreas Head		Reference	Reference	Reference
	Pancreas Body Tail		0.704	0.670–0.739	< 0.001
	Pancreas Other		0.844	0.795–0.897	< 0.001
Grade		< 0.001			< 0.001
	I		Reference	Reference	Reference
	II		2.409	2.260–2.567	< 0.001
	III/IV		3.274	3.064–3.498	< 0.001
	Unknown		1.578	1.449–1.719	< 0.001
T stage		< 0.001			< 0.001
	T1		Reference	Reference	Reference
	T2		1.407	1.335–1.483	< 0.001
	T3		1.595	1.503–1.692	< 0.001
	T4		2.396	2.192–2.620	< 0.001
N stage		< 0.001			< 0.001
	N0		Reference	Reference	Reference
	N1		1.617	1.550–1.688	< 0.001
	N2		2.078	1.975–2.186	< 0.001
Treatment methods		< 0.001			< 0.001
	Only surgery		Reference	Reference	Reference
	Surgery + chemotherapy		0.773	0.739–0.809	< 0.001
	Neoadjuvant radiotherapy		0.855	0.776–0.943	0.002
	Adjuvant radiotherapy		0.719	0.686–0.752	< 0.001
Regional nodes examined		< 0.001			< 0.001
	< 15		Reference	Reference	Reference
	≥15		0.828	0.797–0.859	< 0.001
	Unknown		1.133	0.954–1.346	0.156

OS Overall Survival, CI Confidence intervals, HR Hazard ratios