Table 1 Baseline characteristics of the 1075 patients

Age, years (1 missing)

70.4 [59.4–80.2]

67.3 [56.4–78.8]

66.6 [60.9–77.3]

71.6 [59.4–80.3]

0.39

Male sex

384 (61.7)

47 (63.5)

19 (67.9)

206 (58.7)

0.64

Hospital LOS before ICU admission, days

1 [1–3]

1.5 [1–5]

2 [1–6.5]

1 [1–2]

0.08

Weight, kg (162 missing)

73 [61–87]

71 [62–88]

61 [55–74]

73 [60–85]

0.06

BMI, kg/m² (270 missing)

26 [22.8–30.9]

25 [22.2–30.2]

23.4 [19.2–26.7]

25.5 [21.8–30.5]

0.09

Admission diagnosis (12 missing)

<0.01

 COPD exacerbation

98 (16)

8 (11.1)

2 (7.4)

93 (26.6)

 Acute respiratory failure

366 (59.6)

46 (63.9)

13 (48.1)

183 (52.3)

–

 Coma as referral diagnosis related to hypercapnia

21 (3.4)

2 (2.8)

5 (18.5)

7 (2)

–

 Miscellaneous

129 (21)

16 (22.2)

7 (25.9)

67 (19.1)

Chronic disease^a

 Heart failure

144 (23.2)

15 (20.3)

4 (14.3)

87 (24.8)

0.55

 Respiratory failure

256 (41.2)

32 (43.2)

6 (21.4)

186 (53)

<0.01

 Hepatic failure

25 (4)

3 (4.1)

0 (0)

8 (2.3)

0.36

 Renal failure

42 (6.8)

4 (5.4)

3 (10.7)

19 (5.4)

0.64

 Immunosuppression

112 (18)

13 (17.6)

4 (14.3)

39 (11.1)

0.04

McCabe and Jackson classification (14 missing)

 Nonfatal

277 (45.3)

35 (48.6)

11 (40.7)

159 (45.4)

0.38

 Ultimately fatal disease

287 (46.9)

31 (43.1)

13 (48.1)

176 (50.3)

 Fatal within 1 year

48 (7.8)

6 (8.3)

3 (11.1)

15 (4.3)

Charlson comorbidity index

2 [1–3]

1 [1–3]

1.5 [0.5–3]

2 [1–3]

0.22

SAPS II

37 [30–47]

35.5 [26–45]

43.5 [34.5–50.5]

33 [25–42]

<0.01

SOFA

4 [2–5]

4 [3–6]

4.5 [3.5–7]

4 [2–5]

0.02