Table 4 Moderator analyses for studies in patients with traumatic brain injury (k = 5)

Study design

0.154

Multicenter

4

1.46

1.08-1.98

0.014

9.17^*

67.29

Single-center

1

0.32

0.04-2.50

0.280

-

-

Hyperoxia, definition

0.019

First PaO₂

2

1.79

1.36-2.36

0.000

1.09

8.51

Highest PaO₂

1

0.32

0.04-2.50

0.280

-

-

Mean PaO₂

1

1.56

1.18-2.07

0.002

-

-

Worst PaO₂

1

0.94

0.65-1.36

0.743

-

-

Hyperoxia, time of assessment

0.154

First 24 hours

4

1.46

1.08-1.98

0.014

9.17^*

67.29

Beyond the first 24 hours

1

0.32

0.04-2.50

0.280

-

-

PaO ₂ cutoff

0.126

<300 mmHg (moderate hyperoxia)

3

1.14

0.68-1.90

0.618

6.32^*

68.34

≥300 mmHg (extreme hyperoxia)

2

1.79

1.36-2.36

0.000

1.09

8.51

Comparator group

0.824

Not exposed to hyperoxia

2

1.08

0.20-5.89

0.933

2.94

66.03

Normoxia

3

1.31

0.95-1.81

0.101

4.93

59.47

k

Beta

P

Study quality

NOS score

5

0.26

0.281