Table 2 Univariate and multivariate analysis for OS of all patients(n = 21,030)

Insurance Recode

< 0.001

Insured

Reference

Reference

Reference

No/unknown

1.201

1.152–1.253

< 0.001

Marital status

< 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

< 65

Reference

Reference

Reference

≥65

1.436

1.384–1.489

< 0.001

Race recode

0.508

White

Reference

Reference

Reference

Other

1.016

0.970–1.065

0.508

Sex

< 0.001

Female

Reference

Reference

Reference

Male

1.106

1.068–1.147

< 0.001

Tumor site

< 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

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

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

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

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

< 15

Reference

Reference

Reference

≥15

0.828

0.797–0.859

< 0.001

Unknown

1.133

0.954–1.346

0.156