Table 2 Univariate analysis of variables associated with mortality at day 28 in the overall population

Demographic variables

 Age (years)

56 ± 15

60 ± 15

1.02 (0.99–1.05)

 Gender (male)

54 (67 %)

23 (68 %)

0.96 (0.41–2.25)

 ICU admission before 2011

24 (30 %)

14 (41 %)

1.66 (0.72–3.82)

 Noninvasive ventilation as a first-line therapy

34 (42 %)

22 (65 %)

2.67 (1.16–6.12)

 SAPS II score

42 ± 12

47 ± 13

1.036 (1.00–1.07)

 Modified SOFA score excluding respiratory item

3 (1–6)

4 (1–7)

1.06 (0.93–1.21)

 Knaus chronic health status score

  A

24 (30 %)

10 (29 %)

1

  B

31 (38 %)

8 (24 %)

0.62 (0.21–1.81)

  C

23 (28 %)

13 (38 %)

1.36 (0.50–3.70)

  D

3 (3.7 %)

3 (8.8 %)

2.40 (0.41–13.98)

 Mac Cabe classification

  1

28 (35 %)

11 (32 %)

1

  2

37 (46 %)

12 (35 %)

0.83 (0.32–2.14)

  3

16 (20 %)

11 (32 %)

1.75 (0.62–4.94)

 Type of immunosuppression

  Hematologic cancer or neutropenia

49 (60 %)

15 (44 %)

1

  Solid cancer

9 (11 %)

10 (29 %)

3.53 (1.21–10.27)

 Drug-induced immunosuppression

21 (26 %)

9 (26 %)

1.41 (0.54–3.70)

  Acquired immune deficiency syndrome

2 (2 %)

0 (0 %)

0.64 (0.02–27.52)

Variables at inclusion

 Heart rate (bpm)

111 ± 23

113 ± 21

1.00 (0.99–1.02)

 Systolic arterial blood pressure (mmHg)

126 ± 24

126 ± 29

1.00 (0.98–1.02)

 Diastolic arterial blood pressure (mmHg)

67 ± 18

67 ± 13

1.00 (0.98–1.02)

 Respiratory rate (breaths/min)

28 (25–32)

30 (27–34)

1.04 (0.98–1.10)

 SpO₂ (%)

96 (94–99)

94 (90–97)

0.90 (0.83–0.97)

 Body temperature (°C)

38.0 ± 1.2

37.7 ± 0.9

0.82 (0.58–1.18)

 pH

7.46 (7.42–7.49)

7.44 (7.40–7.49)

0.59 (0.00–21.07)

 Sodium bicarbonate (mmol/l)

24 (22–27)

24 (22–27)

1.03 (0.94–1.12)

 PaO₂-to-FiO₂ ratio (mmHg)

158 ± 59

141 ± 48

0.99 (0.99–1.00)

 PaO₂-to-FiO₂ ratio ≤ 200 mmHg

62 (77 %)

29 (85 %)

1.78 (0.60–5.23)

 PaO₂ (mmHg)

74 (61–88)

70 (57–93)

1.00 (0.99–1.01)

 PaCO₂ (mmHg)

34 (31–40)

34 (31–45)

1.01 (0.97–1.06)

 PaCO₂ > 45 mmHg

8 (10 %)

6 (18 %)

1.96 (0.62–6.14)

 Bilateral lung infiltrate

69 (85 %)

27 (79 %)

0.67 (0.24–1.89)

Vasopressors within 24 h after ICU admission

10 (12 %)

13 (38 %)

2.18 (0.85–5.62)

Immunosuppressive drug during ICU stay

22 (27 %)

6 (17 %)

0.58 (0.21–1.58)

Cause of respiratory failure

 Documented infection

38 (47 %)

17 (50 %)

1

 Cardiogenic pulmonary edema

10 (12 %)

0 (0 %)

0.11 (0.01–2.17)

 Specific

11 (14 %)

8 (24 %)

1.63 (0.56–4.76)

 Other identified causes

12 (15 %)

6 (18 %)

1.14 (0.37–3.54)

 Not identified cause

10 (12 %)

3 (9 %)

0.73 (0.19–2.91)