Table 2 Pooled effect sizes and 95% confidence interval (CI)
| Â | Supine | Semi-recumbent | Lateral | Prone |
|---|---|---|---|---|
Ventilator-associated pneumonia | ||||
 Supine |  | 0.38 (0.25 to 0.52) | NA | 0.79 (0.57 to 1.02) |
 Semi-recumbent | − 0.15 (− 0.30 to 0.01) |  | 0.13 (0.02 to 1.03) | 0.86 (0.66 to 1.11) |
 Lateral | − 0.18 (− 0.71 to 0.35) | − 0.04 (− 0.54 to 0.47) |  | NA |
 Prone | − 0.07 (− 0.27 to 0.14) | 0.08 (− 0.16 to 0.32) | 0.11 (− 0.45 to 0.67) |  |
Mortality | ||||
 Supine |  | 0.83 (0.53 to 1.13) | NA | 0.71 (0.50 to 0.91) |
 Semi-recumbent | − 0.05 (− 0.13 to 0.04) |  | 1.27 (0.92 to 1.76) | 1.03 (0.84 to 1.26) |
 Lateral | 0.02 (− 0.15 to 0.18) | 0.06 (− 0.08 to 0.21) |  | NA |
 Prone | − 0.09 (− 0.20 to 0.13) | − 0.05 (− 0.15 to 0.05) | − 0.11 (− 0.29 to 0.07) |  |
ICU length of stay | ||||
 Supine |  | 1.02 (− 5.50 to 7.54) | NA | − 0.89 (− 6.49 to 4.72) |
 Semi-recumbent | 1.09 (− 5.12 to 7.29) |  | − 1.25 (− 1.60 to − 0.90) | NA |
 Lateral | − 0.16 (− 13.40 to 13.03) | − 1.25 (− 12.89 to 10.39) |  | NA |
 Prone | − 0.81 (− 7.72 to 6.11) | − 1.89 (− 11.19 to 7.39) | − 0.64 (− 15.33 to 14.24) |  |
Hospital length of stay | ||||
 Supine |  | − 6.94 (− 20.30 to 6.43) | NA | 5.80 (− 8.25 to 19.85) |
 Semi-recumbent | − 7.29 (− 22.74 to 8.17) |  | − 1.25 (− 1.92 to − 0.58) | NA |
 Lateral | − 8.54 (− 39.14 to 22.07) | − 1.25 (− 27.67 to 25.17) |  | NA |
 Prone | 5.79 (− 24.41 to 36.01) | 13.09 (− 20.84 to 47.02) | 14.33 (− 28.67 to 57.34) |  |
Duration of mechanical ventilation | ||||
 Supine |  | − 3.36 (− 7.81 to 1.09) | NA | − 2.83 (− 8.03 to 2.36) |
 Semi-recumbent | − 3.26 (− 6.31 to − 0.20) |  | 0.50 (0.27 to 0.73) | − 0.40 (− 1.54 to 0.74) |
 Lateral | − 2.76 (− 9.43 to 3.91) | 0.50 (− 5.42 to 6.43) |  | NA |
 Prone | − 3.28 (− 8.05 to 1.49) | − 0.03 (− 4.70 to 4.65) | − 0.52 (− 8.08 to 7.03) |  |