Table 1 Baseline characteristics of the study participants before and after propensity score matching

Total

1331 (3.54)

36,315 (96.46)

1185 (11.11)

9480 (88.89)

Age, years (mean ± SD)

65.02 ± 12.97

62.84 ± 20.65

<0.0001

65.90 ± 13.47

65.48 ± 14.99

0.3005

Age group, years

<0.0001

0.8569

 <50

159 (11.95)

8454 (23.28)

152 (12.83)

1264 (13.33)

 50–64

422 (31.71)

7079 (19.49)

339 (28.61)

2731 (28.81)

 ≧65

750 (56.35)

20,782 (57.23)

694 (58.57)

5485 (57.86)

Sex

<0.0001

0.2491

 Female

689 (51.77)

13,407 (36.92)

575 (48.52)

4432 (46.75)

 Male

642 (48.23)

22,908 (63.08)

610 (51.48)

5048 (53.25)

Comorbidity

 Diabetes

703 (52.82)

9779 (26.93)

<0.0001

568 (47.93)

4379 (46.19)

0.2573

 Hypertension

903 (67.84)

15,755 (43.38)

<0.0001

757 (63.88)

5954 (62.81)

0.4697

 CAD

458 (34.41)

8173 (22.51)

<0.0001

377 (31.81)

2948 (31.10)

0.6153

 Liver cirrhosis

137 (10.29)

2954 (8.13)

0.0048

120 (10.13)

1025 (10.81)

0.4722

 COPD

175 (13.15)

8715 (24.00)

<0.0001

175 (14.77)

1394 (14.70)

0.9538

 Cancer

184 (13.82)

7912 (21.79)

<0.0001

183 (15.44)

1475 (15.56)

0.9172

 Stroke

368 (27.65)

9952 (27.40)

0.8448

343 (28.95)

2711 (28.60)

0.8027

 CHF

279 (20.96)

5024 (13.83)

<0.0001

215 (18.14)

1699 (17.92)

0.8514

Department to which admitted

<0.0001

0.6634

 Surgery

325 (24.42)

14,358 (39.54)

324 (27.34)

2649 (27.94)

 Medical

1006 (75.58)

21,957 (60.46)

861 (72.66)

6831 (72.06)

Number of organ failures (other than lungs and kidneys)

<0.0001

0.8884

 0

960 (72.13)

28,900 (79.58)

867 (73.16)

6979 (73.62)

 1

346 (26.00)

6779 (18.67)

294 (24.81)

2298 (24.24)

 ≧2

25 (1.88)

636 (1.75)

24 (2.03)

203 (2.14)

Ventilator duration (days) (continuous)

11.69 ± 25.34

18.15 ± 84.99

<0.0001

11.57 ± 25.23

11.93 ± 29.57

0.6494

ICU days, mean ± SD

10.25 ± 16.48

9.75 ± 17.18

0.2839

9.93 ± 15.32

10.07 ± 17.18

0.7883

Hospital days, mean ± SD

24.06 ± 28.14

25.28 ± 54.04

0.1391

23.92 ± 28.21

22.89 ± 32.11

0.2444