|
Study group
|
Outcomes
|
|---|
| |
Number of studies (n)
|
Number of participants (n)
|
test of association
|
Test of heterogeneity
|
|---|
|
RR
|
95%CI
|
p value
|
Model
|
p value
|
I2
|
I2 test for subgroup differences (%)
|
p for the interaction between subgroup and treatment
|
|---|
|
difficult intubation
|
|
Study design
|
|
Cohort
|
3
|
5567
|
3.41
|
0.88–13.25
|
0.08
|
RE
|
0.14
|
50
|
23
|
0.25
|
|
Case-control
|
2
|
95,407
|
1.50
|
1.03–2.18
|
0.03
|
RE
|
0.08
|
67
|
|
Position
|
|
Sniffing
|
2
|
394
|
5.77
|
2.29–14.58
|
0.0002
|
RE
|
0.63
|
0
|
89.8
|
0.002
|
|
Supine
|
3
|
100,570
|
1.30
|
1.17–1.44
|
< 0.00001
|
RE
|
0.59
|
0
|
|
difficult laryngoscopy
|
|
Study design
|
|
Cohort
|
6
|
9111
|
1.85
|
1.31–2.63
|
0.0005
|
RE
|
0.08
|
49
|
67
|
0.08
|
|
Case-control
|
3
|
103,277
|
1.34
|
1.22–1.48
|
< 0.00001
|
RE
|
0.87
|
0
|
|
Position
|
|
Sniffing
|
4
|
2210
|
2.0
|
0.97–4.15
|
0.06
|
RE
|
0.03
|
67
|
0
|
0.42
|
|
Supine
|
5
|
110,178
|
1.47
|
1.23–1.76
|
< 0.0001
|
RE
|
0.22
|
30
|
|
Mallamp-ati ≥ 3
|
|
Study design
|
|
Cohort
|
9
|
4189
|
1.9
|
1.12–3.21
|
0.02
|
RE
|
< 0.00001
|
85
|
0
|
0.6
|
|
Case-control
|
3
|
1489
|
1.62
|
1.27–2.08
|
0.0001
|
RE
|
0.61
|
0
| | |
- CI confidence interval, RE random-effect model, RR risk ratio, I2 a test for heterogeneity, I2 > 50% indicates substantial heterogeneity
