Table 2 Univariate analysis. Early vs. late intubation

General characteristics

 Male, n (%)

670 (73)

317 (72)

0.9

 Age (years), median (p25–75)

64 (56‒71)

62 (50‒73)

0.01

Comorbidities

 Hypertension, n (%)

466 (50)

175 (40)

<0.001

 Obesity (> 30 kg/m²), n (%)

354 (38)

150 (34)

0.1

 Diabetes, n (%)

262 (28)

85 (19)

<0.001

 Chronic lung disease, n (%)

69 (7)

24 (5)

0.2

 Asthma, n (%)

60 (6)

26 (6)

0.7

 Immunosuppression, n (%)

60 (6)

28 (6)

0.9

 Chronic kidney disease, n (%)

58 (6)

24 (5)

0.5

 Chronic heart failure, n (%)

32 (3)

18 (4)

0.5

 Ischemic heart disease, n (%)

64 (7)

27 (6)

0.6

Severity of illness

 SOFA, median (p25–75)

4 (3‒7)

3 (2‒6)

<0.001

 APACHE II, median (p25–75)^a

14 (10‒17)

13 (10‒16)

0.001

 PaO₂/Fio₂ ratio at admission, median (p25–75)

100 (75‒148)

116 (90‒152)

<0.001

 Shock at admission, n (%)

281 (30)

36 (8)

<0.001

Laboratory variables

 Procalcitonin (ng/ml), median (p25–75)

0.3 (0.1‒0.9)

0.3 (0.1‒0.8)

0.06

 C-reactive protein (mg/dL), median (p25–75)

15 (9‒23)

14 (7‒22)

0.6

 White blood cells count (109/ml), median (p25–75)

8.6 (6.3‒12)

8.2 (5.8‒11.5)

0.04

 LDH (U/L), median (p25–75)

512 (405‒629)

484 (384‒583)

0,002

 D-dimer (ng/ml), median (p25–75)

1128 (600‒2496)

991 (595‒2437)

0.1

 Creatinine (mg/dL), median (p25–75)

0.8 (0.7‒1.1)

0.8 (0.7‒1.05)

0.1

 Urea (mg/dL), median (p25–75)

45 (32‒60)

44 (33‒57)

0.5

 Lactate (mmol/L), median (p25–75)

1.5 (1.1‒2.1)

1.6 (1.1‒2.3)

0.2

Outcomes

 Days for IVM, median (p25–75)^b

19 (12‒34)

20 (12‒34)

0.99

 ICU mortality, n (%)

293 (32)

163 (37)

0.05

 ICU LOS, median (p25–75)^b

20 (12‒35)

19 (12‒34)

0.2

 Hospital mortality, n (%)

309 (33)

176 (40)

0.03

 Hospital LOS, median (p25–75)^b

35 (23‒53)

37 (24‒54)

0.7