Table 3 The Results of the meta-analysis of potential risk factors

Demographics

Advanced age

Continuous

22

0.27

1.07

1.05–1.10

< 0.001

Fixed

Dichotomous

0

0.64

2.55

2.04–3.19

< 0.001

Fixed

Advanced age > 70 years

Dichotomous

0

0.70

2.34

1.77–3.09

< 0.001

Fixed

Advanced age > 80 years

Dichotomous

0

0.45

2.98

2.06–4.31

< 0.001

Fixed

60–69 years vs 70–79 years

Stratification

0

0.65

1.38

1.20–1.59

< 0.001

Fixed

60–69 years vs 80–89 years

10

0.29

1.82

1.59–2.09

< 0.001

60–69 years vs ≥90 years

50

0.16

2.08

1.74–2.49

< 0.001

Male sex

Dichotomous

0

0.76

2.04

1.78–2.34

< 0.001

Fixed

High BMI

Continuous

36

0.21

0.85

0.79–0.90

< 0.001

Fixed

Functional status

Dichotomous

0

0.76

3.13

2.11–4.63

< 0.001

Fixed

History of smoking

Dichotomous

0

0.58

2.89

2.34–3.57

< 0.001

Fixed

Comorbidity

COPD

Dichotomous

17

0.27

3.44

2.83–4.19

< 0.001

Fixed

History of stroke

Dichotomous

0

0.95

3.10

2.28–4.20

< 0.001

Fixed

CVA

Dichotomous

0

0.35

1.56

1.26–1.93

< 0.001

Fixed

History of cancer

Dichotomous

0

0.56

3.77

2.13–6.67

< 0.001

Fixed

Number of comorbidities

Dichotomous

92

< 0.001

5.16

3.16–8.42

< 0.001

Random

Number of comorbidities = 1

Stratification

0

0.96

3.09

2.77–3.45

< 0.001

Fixed

Number of comorbidities = 2

0

0.40

7.42

6.24–8.84

< 0.001

Number of comorbidities = 3

0

0.41

6.60

4.48–9.72

< 0.001

Cognitive function dysfunction

Dichotomous

5

0.31

2.75

1.86–4.07

< 0.001

Fixed

Surgical

Time from injury to operation

Continuous

2

0.36

1.09

1.07–1.12

< 0.001

Fixed

Dichotomous

15

0.31

3.59

2.88–4.48

< 0.001

Fixed

ASA

Dichotomous

0

0.45

2.72

2.27–3.26

< 0.001

Fixed

Type of anesthesia

Dichotomous

16

0.31

0.24

0.18–0.32

< 0.001

Fixed

Duration of surgery

Continuous

89

0.003

1.02

1.00–1.03

0.01

Random

Dichotomous

0

0.64

3.56

1.84–6.87

< 0.001

Fixed

ICU

Dichotomous

7

0.34

2.92

1.93–4.41

< 0.001

Fixed

Time of Mechanical ventilation

Continuous

71

0.06

4.48

1.89–10.64

< 0.001

Random

Type of operation

Dichotomous

0

0.74

5.03

2.58–9.81

< 0.001

Fixed

Laboratory

Hypoalbuminemia

Dichotomous

29

0.16

2.75

2.25–3.36

< 0.001

Fixed

Hypoalbuminemia< 3.0 g/dL

Dichotomous

0

0.66

3.03

1.93–4.73

< 0.001

Fixed

Hypoalbuminemia< 3.5 g/dL

Dichotomous

45

0.07

2.68

2.15–3.36

< 0.001

Fixed

Anemia

Dichotomous

0

0.80

2.97

2.14–4.11

< 0.001

Fixed

High RDW

Continuous

0

0.43

3.14

2.35–4.20

< 0.001

Fixed

High Cr

Continuous

0

0.87

3.11

1.57–6.19

< 0.001

Fixed

Hyperglycemia

Dichotomous

86

0.007

6.39

0.58–70.06

0.13

Random