Table 2 Results of survival analysis using the Cox proportional hazard model to examine the association between surgical volume and cancer-specific mortality

  Male

1.132

0.914

1.401

0.2571

  Female

1.000

–

–

–

  −39

1.000

–

–

–

  40–49

1.036

0.568

1.892

0.9071

  50–59

1.136

0.640

2.016

0.6640

  60–69

1.805

1.031

3.162

0.0388

  70+

4.252

2.406

7.513

<.0001

  −40

1.033

0.755

1.412

0.8410

  41–70

1.166

0.859

1.582

0.3249

  71–90

1.077

0.797

1.455

0.6303

  91+

1.000

–

–

–

  Medical Aid

1.393

0.863

2.247

0.1749

  NHI, self-employed

0.991

0.808

1.217

0.9338

  NHI, employed

1.000

–

–

–

  2004

1.000

–

–

–

  2005

0.881

0.618

1.255

0.4818

  2006

0.854

0.589

1.240

0.4078

  2007

1.008

0.707

1.438

0.9640

  2008

0.765

0.519

1.127

0.1752

  2009

1.050

0.714

1.543

0.8043

  2010

0.787

0.525

1.179

0.2460

  2011

0.664

0.415

1.061

0.0868

  2012

1.173

0.733

1.879

0.5060

  2013

0.948

0.403

2.232

0.9032

  Total gastrectomy

2.228

1.823

2.724

<.0001

  Subtotal gastrectomy

1.000

–

–

–

  With chemotherapy and radiotherapy

4.605

3.010

7.043

<.0001

  With chemotherapy

6.139

4.935

7.636

<.0001

  With radiotherapy

9.068

4.071

20.199

<.0001

  Only surgery

1.000

–

–

–

  Yes

0.983

0.403

2.398

0.9708

  No

1.000

–

–

–

 CCI

1.051

0.995

1.111

0.0739

  Low

1.000

–

–

–

  Mid-low

0.773

0.608

0.983

0.0356

  Mid-high

0.541

0.372

0.788

0.0014

  High

0.659

0.473

0.917

0.0135

  Capital area

1.131

0.924

1.385

0.2316

  Others

1.000

–

–

–

  General hospital

0.311

0.133

0.729

0.0072

  Hospital

1.000

–

–

–