Table 1 Comparison between frequent and non-frequent ED users

Total

4,063,640

100.0

3,926,032

96.6

137,608

3.4

Sex

 < .0001

 Male

2,002,672

49.3

1,937,177

96.7

65,495

3.3

 Female

2,060,968

50.7

1,988,855

96.5

72,113

3.5

Age (years)

 < .0001

  ≤ 9

674,626

16.6

648,430

96.1

26,196

3.9

 10–19

292,998

7.2

286,278

97.7

6,720

2.3

 20–29

457,637

11.3

446,438

97.6

11,199

2.4

 30–39

447,022

11.0

435,239

97.4

11,783

2.6

 40–49

459,047

11.3

445,425

97.0

13,622

3.0

 50–59

565,865

13.9

547,863

96.8

18,002

3.2

 60–69

478,823

11.8

461,385

96.4

17,438

3.6

  ≥ 70

687,622

16.9

654,974

95.3

32,648

4.7

Region

 < .0001

 Seoul

829,176

20.4

802,376

96.8

26,800

3.2

 Busan

176,214

4.3

171,217

97.2

4,997

2.8

 Daegu

152,200

3.7

148,412

97.5

3,788

2.5

 Incheon

247,928

6.1

238,239

96.1

9,689

3.9

 Gwangju

100,829

2.5

96,637

95.8

4,192

4.2

 Daejeon

105,453

2.6

100,992

95.8

4,461

4.2

 Ulsan

61,968

1.5

60,629

97.8

1,339

2.2

 Sejong

11,554

0.3

11,229

97.2

325

2.8

 Gyeonggi

1,133,162

27.9

1,096,411

96.8

36,751

3.2

 Gangwon

138,037

3.4

133,738

96.9

4,299

3.1

 Chungcheong

342,784

8.4

332,349

97.0

10,435

3.0

 Jeolla

264,711

6.5

253,129

95.6

11,582

4.4

 Gyeongsang

406,565

10.0

391,352

96.3

15,213

3.7

 Jeju

93,059

2.3

89,322

96.0

3,737

4.0

Insurance types

 < .0001

 National Health Insurance

3,622,424

89.1

3,503,781

96.7

118,643

3.3

 Auto insurance

162,973

4.0

159,746

98.0

3,227

2.0

 Industrial accident insurance

8,556

0.2

8,334

97.4

222

2.6

 Medical Aid (Types 1 and 2)

191,451

4.7

177,449

92.7

14,002

7.3

 General insurance

59,510

1.5

58,458

98.2

1,052

1.8

 Other insurance

18,726

0.5

18,264

97.5

462

2.5

Residence in underserved emergency Medical Services areas

 < .0001

 No

3,630,066

89.3

3,506,874

96.6

123,192

3.4

 Yes

433,574

10.7

419,158

96.7

14,416

3.3

Number of emergency medical institutions

 < .0001

 Above the national average

1,306,744

32.2

1,259,050

96.4

47,694

3.6

 Below the national average

2,756,896

67.8

2,666,982

96.7

89,914

3.3

Number of beds

 < .0001

 Above the national average

1,408,186

34.7

1,358,076

96.4

50,110

3.6

 Below the national average

2,655,454

65.3

2,567,956

96.7

87,498

3.3

Regional income decile

 < .0001

 1^st quartile (lowest)

405,600

10.0

392,447

96.8

13,153

3.2

 2^nd quartile

398,239

9.8

382,396

96.0

15,843

4.0

 3^rd quartile

395,879

9.7

382,380

96.6

13,499

3.4

 4^th quartile

416,699

10.3

401,957

96.5

14,742

3.5

 5^th quartile

428,062

10.5

410,577

95.9

17,485

4.1

 6^th quartile

372,942

9.2

359,150

96.3

13,792

3.7

 7^th quartile

433,250

10.7

419,650

96.9

13,600

3.1

 8^th quartile

371,584

9.1

359,746

96.8

11,838

3.2

 9^th quartile

439,894

10.8

427,256

97.1

12,638

2.9

 10^th quartile (highest)

401,491

9.9

390,473

97.3

11,018

2.7

Cancer

 < .0001

 No

3,929,064

96.7

3,805,592

96.9

123,472

3.1

 Yes

134,576

3.3

120,440

89.5

14,136

10.5

Hypertension

 < .0001

 No

4,036,995

99.3

3,900,545

96.6

136,450

3.4

 Yes

26,645

0.7

25,487

95.7

1,158

4.3

Diabetes

 < .0001

 No

4,035,224

99.3

3,899,176

96.6

136,048

3.4

 Yes

28,416

0.7

26,856

94.5

1,560

5.5

Renal failure

 < .0001

 No

4,015,410

98.8

3,881,705

96.7

133,705

3.3

 Yes

48,230

1.2

44,327

91.9

3,903

8.1

Mental illness

 < .0001

 No

3,996,542

98.3

3,862,282

96.6

134,260

3.4

 Yes

67,098

1.7

63,750

95.0

3,348

5.0

Korean Triage and Acuity Scale

 < .0001

 Level 1 (Resuscitation)

42,374

1.0

40,698

96.0

1,676

4.0

 Level 2 (Emergent)

216,409

5.3

208,062

96.1

8,347

3.9

 Level 3 (Urgent)

1,493,106

36.7

1,438,032

96.3

55,074

3.7

 Level 4 (Less urgent)

1,967,646

48.4

1,913,001

97.2

54,645

2.8

 Level 5 (Non-urgent)

344,105

8.5

326,239

94.8

17,866

5.2