Table 1 Baseline characteristics before and after propensity score matching

Age category, years

 15–59

8623 (11)

9551 (8)

11

6012 (10)

6233 (10)

1

 60–69

12,549 (16)

15,166 (12)

11

9097 (15)

9182 (15)

0

 70–79

21,590 (27)

29,166 (23)

9

16,293 (26)

16,534 (27)

1

 80–89

27,818 (35)

49,134 (40)

9

23,419 (38)

23,159 (37)

1

 ≥ 90

8066 (10)

21,203 (17)

20

7531 (12)

7244 (12)

1

Male

45,539 (58)

65,536 (53)

10

34,891 (56)

35,036 (56)

1

Smoking history

 Nonsmoker

39,997 (51)

69,204 (56)

10

32,837 (53)

32,462 (52)

1

 Current/past smoker

28,244 (36)

39,154 (32)

9

21,569 (35)

21,841 (35)

1

 Unknown

10,405 (13)

15,862 (13)

1

7946 (13)

8049 (13)

1

Body mass index at admission, kg/m²

 < 18.5

11,398 (14)

20,731 (17)

6

9487 (15)

9462 (15)

0

 18.5–24.9

42,295 (54)

66,216 (53)

1

33,419 (54)

33,515 (54)

0

 25.0–29.9

13,836 (18)

20,142 (16)

4

10,615 (17)

10,595 (17)

0

 ≥ 30.0

4786 (6)

6627 (5)

3

3653 (6)

3666 (6)

0

 Missing

6331 (8)

10,504 (8)

2

5178 (8)

5114 (8)

0

Japan Coma Scale score at admission

 Alert

55,363 (70)

90,007 (72)

5

45,087 (72)

45,263 (73)

1

 Confusion

14,730 (19)

25,663 (21)

5

11,892 (19)

11,696 (19)

1

 Somnolence

3886 (5)

4368 (4)

7

2638 (4)

2645 (4)

0

 Coma

4667 (6)

4182 (3)

12

2735 (4)

2748 (4)

0

Physical function at admission

 Total/severe dependence (BI 0–60)

44,788 (57)

75,717 (61)

8

36,189 (58)

35,992 (58)

1

 Slight/moderate dependence (BI 61–99)

2886 (4)

7479 (6)

11

2652 (4)

2515 (4)

1

 Independent (BI 100)

14,395 (18)

18,982 (15)

8

10,864 (17)

11,160 (18)

1

 Missing

16,577 (21)

22,042 (18)

8

12,647 (20)

12,685 (20)

0

Cognitive function before admission

 No dementia

62,514 (79)

87,997 (71)

20

48,040 (77)

48,328 (78)

1

 Mild dementia

11,281 (14)

23,981 (19)

13

9907 (16)

9729 (16)

1

 Moderate/severe dementia

4,851 (6)

12,242 (10)

14

4405 (7)

4295 (7)

1

 Home medical care before admission

4628 (6)

9537 (8)

7

4030 (6)

4044 (6)

0

Location before hospitalization

 Home

69,582 (88)

108,333 (87)

4

55,212 (89)

55,371 (89)

1

 Other hospitals

5069 (6)

5481 (4)

9

3430 (6)

3418 (5)

0

 Nursing home

3995 (5)

10,406 (8)

13

3710 (6)

3563 (6)

1

 Ambulance use

57,243 (73)

76,205 (61)

25

43,223 (69)

43,657 (70)

2

 Admission on a weekend

19,860 (25)

28,864 (23)

5

15,380 (25)

15,337 (25)

0

Comorbidities

 Ischemic heart disease

23,479 (30)

32,383 (26)

8

17,885 (29)

18,039 (29)

1

 Diabetes mellitus

25,442 (32)

35,323 (28)

9

19,500 (31)

19,644 (32)

1

 Hypertension

42,660 (54)

64,774 (52)

4

33,757 (54)

33,743 (54)

0

 Hyperlipidemia

19,133 (24)

26,527 (21)

7

14,714 (24)

14,788 (24)

0

 Atrial flutter/fibrillation

18,157 (23)

35,068 (28)

12

15,533 (25)

15,433 (25)

0

 Chronic kidney disease

13,750 (17)

19,434 (16)

5

10,384 (17)

10,327 (17)

0

 Cancer

3429 (4)

5646 (5)

1

2796 (4)

2767 (4)

0

Charlson comorbidity index

1.4 ± 1.4

1.3 ± 1.4

7

1.4 ± 1.3

1.4 ± 1.4

0

Treatments on day of admission

 Respiratory support

  No supplemental oxygen

13,848 (18)

21,594 (17)

1

12,005 (19)

12,106 (19)

0

  Supplemental oxygen

24,938 (32)

71,027 (57)

53

24,121 (39)

23,535 (38)

2

  Noninvasive ventilation

31,769 (40)

28,080 (23)

39

23,015 (37)

23,351 (37)

1

  Intubation

8091 (10)

3519 (3)

31

3211 (5)

3360 (5)

1

 Intravenous vasodilator

  Carperitide

28,527 (36)

41,402 (33)

6

22,282 (36)

22,343 (36)

0

  Nitrate

33,780 (43)

35,205 (28)

31

23,851 (38)

24,297 (39)

2

  Nicorandil

5742 (7)

4894 (4)

15

3533 (6)

3598 (6)

1

  Calcium-channel blocker

9730 (12)

11,468 (9)

10

6980 (11)

7018 (11)

0

 Diuretic

  Intravenous furosemide

52,132 (66)

84,840 (68)

4

42,043 (67)

41,961 (67)

0

  Tolvaptan

5980 (8)

11,935 (10)

7

5152 (8)

4945 (8)

1

 Inotrope

  Milrinone

1059 (1)

1206 (1)

4

687 (1)

687 (1)

0

  Pimobendan

1473 (2)

2332 (2)

0

1203 (2)

1216 (2)

0

  Dobutamine

11,582 (15)

12,769 (10)

14

7580 (12)

7706 (12)

1

 Vasopressor

  Dopamine

5254 (7)

5419 (4)

10

3205 (5)

3198 (5)

0

  Noradrenaline

5871 (7)

2782 (2)

25

2360 (4)

2399 (4)

0

 Mechanical circulatory support

  Intra-aortic balloon pumping

1818 (2)

538 (0)

16

502 (1)

519 (1)

0

  Extracorporeal membrane oxygenation

375 (0)

101 (0)

8

88 (0)

97 (0)

0

 Other treatment

  Coronary angiography

4252 (5)

2503 (2)

18

2116 (3)

2115 (3)

0

  Percutaneous coronary intervention

1317 (2)

601 (0)

12

539 (1)

545 (1)

0

  Digoxin

3128 (4)

4979 (4)

0

2535 (4)

2596 (4)

1

  Intravenous beta-blockers

3257 (4)

4056 (3)

5

2336 (4)

2365 (4)

0

  Amiodarone

3640 (5)

3712 (3)

9

2369 (4)

2431 (4)

1

  Cardiac pacing

1019 (1)

814 (1)

7

599 (1)

603 (1)

0

  Intermittent renal replacement therapy

3423 (4)

3370 (3)

9

2384 (4)

2430 (4)

0

  Continuous renal replacement therapy

2385 (3)

684 (1)

19

672 (1)

663 (1)

0

  Antibiotics

18,597 (24)

24,182 (19)

10

13,037 (21)

13,067 (21)

0

  Morphine

2421 (3)

2015 (2)

10

1530 (2)

1597 (3)

1

  Red blood cell transfusion

3352 (4)

3660 (3)

7

2108 (3)

2090 (3)

0

 Hospital characteristics

  Tertiary emergency hospital

41,117 (52)

83,724 (67)

31

35,228 (56)

34,513 (55)

2

  Academic hospital

13,678 (17)

11,775 (9)

23

8643 (14)

8985 (14)

2

 Hospital volume, patients per year

  Low (≤ 66)

28,467 (36)

38,650 (31)

11

22,141 (36)

22,355 (36)

1

  Medium (67–129)

28,609 (36)

39,238 (32)

10

21,325 (34)

21,692 (35)

1

  High (≥ 130)

21,570 (27)

46,332 (37)

21

18,886 (30)

18,305 (29)

2