Table 1 Patient characteristics in the total population and by RIFLE class

Number

2420

1588 (65.6 %)

456 (18.8 %)

253 (10.5 %)

123 (5.1 %)

Gender (female)

1000 (41.3 %)

662 (41.7 %)

196 (43 %)

97 (38.3 %)

45 (36.6 %)

.446

Age (years)

59 (47–69)

58 (45–67)

60.5 (50–71)

63 (53–74)

61 (50–72)

<.001

ICU length of stay (days)

3.8 (2–8)

3.4 (2–7)

4.8 (2–9)

4.7 (2–10)

5.3 (2–12)

<.001

Hospital length of stay (days)

17 (8–31)

16.2 (8–29)

18.2 (10–32)

19.9 (8–38)

23.5 (9–40)

.004

Pre-ICU length of stay (days)

0.2 (0–1)

0.2 (0–1)

0.2 (0–1)

0.4 (0–3)

0.4 (0–6)

<.001

Admission type

<.001

 Elective surgical

330 (13.6 %)

244 (15.4 %)

47 (10.3 %)

33 (13 %)

6 (4.9 %)

 Urgent surgical

672 (27.8 %)

460 (29 %)

134 (29.4 %)

59 (23.3 %)

19 (15.4 %)

 Medical

1418 (58.6 %)

884 (55.7 %)

275 (60.3 %)

161 (63.6 %)

98 (79.7 %)

Pre-ICU health state

 Charlson Comorbidity Index

1 (0–2)

0 (0–2)

1 (0–2)

2 (0–4)

2 (0–6)

<0.001

 Chronic cardiac insufficiency

217 (9 %)

118 (7.4 %)

50 (11 %)

32 (12.6 %)

17 (13.8 %)

0.003

 Chronic respiratory insufficiency or COPD

394 (16.3 %)

229 (14.4 %)

95 (20.8 %)

55 (21.7 %)

15 (12.2 %)

<0.001

 Chronic renal insufficiency

96 (4 %)

34 (2.1 %)

12 (2.6 %)

16 (6.3 %)

34 (27.6 %)

<0.001

 Mild or severe liver disease

45 (1.9 %)

19 (1.2 %)

7 (1.5 %)

10 (4 %)

9 (7.3 %)

<0.001

 Metastatic malignancy

96 (4 %)

53 (3.3 %)

18 (3.9 %)

14 (5.5 %)

11 (8.9 %)

0.016

 Haematological malignancy

112 (4.6 %)

54 (3.4 %)

21 (4.6 %)

19 (7.5 %)

18 (14.6 %)

<0.001

 HIV positivity, AIDS, or other immunodeficiency

284 (11.7 %)

151 (9.5 %)

56 (12.3 %)

45 (17.8 %)

32 (26 %)

<0.001

 Diabetes

341 (14.1 %)

168 (10.6 %)

95 (20.8 %)

54 (21.3 %)

24 (19.5 %)

<0.001

 Body mass index

24.7 (22–28)

24.2 (22–27)

25.7 (23–29)

26.1 (23–30)

26 (22–29)

<0.001

Severity of disease markers

 Mechanical ventilation within first 24 hours of ICU stay

2188 (90.4 %)

1426 (89.8 %)

424 (93 %)

230 (90.9 %)

108 (87.8 %)

0.157

 Confirmed infection in the first 24 hours of ICU admission

651 (26.9 %)

337 (21.2 %)

136 (29.8 %)

102 (40.3 %)

76 (61.8 %)

<0.001

 APACHE II Acute Physiology Score (without creatinine)

17 (13–23)

17 (13–22)

17 (14–23)

17 (14–24)

20 (15–26)

<0.001

 APACHE II score (unmodified)

19 (14–25)

18 (14–24)

20 (15–26)

22 (17–28)

29 (23–34)

<0.001

 Total maximum SOFA score (sum of highest SOFA component scores)

9 (6–12)

8 (5–11)

10 (7–13)

12 (8–16)

16 (12–18)

<0.001

  SOFA score on day of discharge

5 (3–7)

4 (3–6)

5 (3–7)

6 (3–9)

7 (5–13)

<0.001