Table 3 Subgroup analysis using Cox proportional hazard model by age, insurance coverage, average pharmaceutical expenditures, region, and number of medical centers

Age (years)

 ≤29

7.351

1.735

31.139

0.0068

 30–59

1.415

0.865

2.313

0.1665

 ≥60

1.301

1.097

1.543

0.0025

Insurance coverage

 Medical aid

0.690

0.316

1.508

0.3518

 NHI, self-employed insured

1.647

1.305

2.078

<0.0001

 NHI, employee insured

1.327

1.083

1.626

0.0063

 Below median

1.447

1.116

1.876

0.0052

 Above median

1.466

1.229

1.751

<0.0001

Region

 Metropolitan

1.370

1.087

1.727

0.0078

 Other

1.508

1.248

1.825

<0.0001

Number of medical centers per 1000 residents

 Below median

1.609

1.302

1.988

<0.0001

 Above median

1.323

1.079

1.622

0.0071

Charlson comorbidity index

 ≤2

1.359

1.148

1.610

0.0004

 ≥3

1.553

1.020

2.364

0.0401