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Table 1 Demographics, baseline characteristics at intensive care unit admission and overall outcome obtained after covariate balancing*

From: Non-invasive oxygenation support in acutely hypoxemic COVID-19 patients admitted to the ICU: a multicenter observational retrospective study

 

Overall

Oxygen mask

High-flow oxygen therapy

Non-invasive ventilation

p

SMD

VR

n = 1093

n = 553

n = 439

n = 1011

Age (years)

63 [54—70]

64 [54—70]

62 [54—70]

63 [53—69]

0.904

 < 0.001

1.11

Sex (female)

354 (32)

179 (32)

142 (32)

33 (32)

1

 < 0.001

–

Body mass index (kg·m−2)

28 [26–31]

28 [25-31]

28 [26–31]

28 [26–31]

0.914

 < 0.001

1.23

Time from hospital admission to ICU admission [days]

1 [0—3]

1 [0—3]

1 [0—3]

2 [1–3]

0.553

 < 0.001

1.22

Comorbidities, n (%)

       

 Cardiovascular

520 (48)

263 (48)

209 (48)

48 (48)

1

 < 0.001

–

 Diabetes

226 (21)

114 (21)

91 (21)

21 (21)

 Cancer

80 (7)

41 (7)

32 (7)

7 (7)

 COPD

79 (7)

40 (7)

32 (7)

7 (7)

 Immunosupression

63 (6)

32 (6)

25 (6)

6 (6)

Leucocytes (G/l)

9 [6–12]

9 [6–12]

9 [6–12]

9 [7–12]

0.782

 < 0.001

1.25

Lymphocytes (G/l)

0.7 [0.5—1.0]

0.7 [0.5—1.0]

0.8 [0.5—1.0]

0.7 [0.5—1.0]

0.551

 < 0.001

1.28

Neutrophil/ lymphocyte ratio

10 [7–17]

11 [6–18]

10 [7–17]

10 [7–18]

0.688

 < 0.001

1.46

Procalcitonin (μg/l)

0.3 [0.1—0.6]

0.3 [0.1—0.6]

0.3 [0.1—0.6]

0.2 [0.1—0.5]

0.254

 < 0.001

1.7

C-reactive protein (mg/l)

113 [23–222]

118 [30—217]

104 [17—227]

114 [30—227]

0.296

 < 0.001

1.42

Lactate (mmol/l)

1.4 [1.1–1.9]

1.3 [1.0—1.9]

1.4 [1.1—1.9]

1.4 [1.2—1.8]

0.052

 < 0.001

1.47

Interleukin-6 (ng/l)

129 [50–329]

132 [50—304]

118 [60—332]

130 [43—354]

0.855

 < 0.001

1.34

D-dimers (μg/l)

1145 [560–2965]

1262 [611–3058]

1040 [494—2760]

1190 [558—3793]

0.07

 < 0.001

1.57

Ferritin (μg/l)

1387 [760–2259]

1325 [779—2254]

1465 [742—2215]

1382 [722—2356]

0.91

 < 0.001

1.58

Intubation, n (%)

897 (82)

501 (91)

307 (70)

89 (88)

 < 0.001

  

Length of ICU stay (days)

14 [7–26]

14 [7–26]

13 [7–26]

13 [8–24]

0.958

  

Ventilator-free survival† (days)

12 [0—24]

8 [0—23]

15 [0—30]

11 [0—24]

 < 0.001

  

ICU mortality, n (%)

310 (28)

167 (30)

106 (24)

37 (36)

0.041

  
  1. Quantitative data are expressed as median [interquartile range]. p values are given for the difference between respiratory strategies. Standardized mean differences (SMD) reflect the maximal mean difference between groups. Variance ratios (VR) reflect the maximal higher-order moments and interactions between groups. COPD—chronic obstructive pulmonary disease; CRP—C-reactive protein; ICU—intensive care unit; PCT—Procalcitonin. † Calculated at 30 days post-intensive care unit admission; patients deceased were assigned 0 ventilator free days
  2. *By applying a weight on each individual subject, a standardized pseudo-population is generated, which slightly differs from the original population (e-Table 4). Causal treatment effect inference is possible in this pseudo-population
  3. **Includes any of the following: arterial hypertension, ischemic heart disease, acute cerebrovascular events