Table 2 VL vs. DL for first-attempt intubation success rate
First outcome | Studies | Patients | Heterogeneity | Heterogeneity statistical method | Effect estimate (p value) |
|---|---|---|---|---|---|
First-attempt intubation success rate | 25 | 5836 | 87%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.03 [0.96–1.11] (p = 0.37) |
Sensitivity analysis | 21 | 5026 | 86%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.11 [1.04–1.19] (p < 0.01) |
Subgroup analysis | |||||
 Intubation site | |||||
 Pre-hospital | 6 | 1395 | 94%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 0.75 [0.56–1.00] (p = 0.05) |
 In-hospital | 19 | 4441 | 87%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.12 [1.04–1.22] (p < 0.01) |
Difficult airway | |||||
 Less | 22 | 4976 | 89%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.02 [0.94–1.11] (p = 0.59) |
 Main | 1 | 97 | _ | Risk ratio (M-H, random, 95% CI) | 1.22 [1.02–1.47] (p = 0.03) |
Cardiac arrest | |||||
 Less | 19 | 4513 | 88%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.09 [1.00–1.18] (p = 0.04) |
 Main | 6 | 1323 | 93%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 0.85 [0.68–1.08] (p = 0.18) |
Study time | |||||
 Lower2011 | 2 | 835 | 98%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 0.73 [0.37–1.41] (p = 0.34) |
 2011–2014 | 8 | 1177 | 92%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.02 [0.81–1.28] (p = 0.85) |
 2015–2018 | 11 | 2040 | 80%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.06 [0.97–1.16] (p = 0.19) |
 Higher2018 | 4 | 1784 | 53%, p = 0.10 | Risk ratio (M-H, random, 95% CI) | 1.16 [1.06–1.26] (p < 0.01) |
Operator proficiency for intubation | |||||
 Experienced | 14 | 3841 | 92%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 0.98 [0.89–1.08] (p = 0.64) |
 Unexperienced | 10 | 1852 | 63%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.11 [0.99–1.24] (p = 0.09) |
Operator proficiency for VL | |||||
 Experienced | 6 | 2119 | 68%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.18 [1.08–1.30] (p < 0.01) |
 Unexperienced | 13 | 2553 | 87%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 0.99 [0.84–1.15] (p = 0.87) |
Operator proficiency was higher for DL than for VL | |||||
 No | 16 | 3971 | 71%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 1.14 [1.06–1.23] (p < 0.01) |
 Yes | 4 | 810 | 85%, p < 0.01 | Risk ratio (M-H, random, 95% CI) | 0.65 [0.49–0.88] (p < 0.01) |