The outcomes of the study
| Outcomes or subgroup analysis | Studies | Study reference no | Patients | RR/MD (95% CI) | I2 | P value |
| Primary outcomes | ||||||
| 90 days mortality | 5 | (9, 11, 14, 21, 28) | 1466 | 0.85 (0.66 to 1.09) | 46% | 0.2 |
| Secondary outcomes | ||||||
| 21–28 days mortality | 6 | (9, 11–13, 21, 28) | 1574 | 0.71 (0.53 to 0.96) | 51% | 0.02 |
| Days free of ventilation at day 28 | 5 | (9, 11, 12, 14, 21) | 1461 | 0.54 (−0.47 to 1.56) | 15% | 0.3 |
| Barotrauma* | 4 | (9, 11, 12, 21) | 1439 | 0.56 (0.37 to 0.86) | 0% | 0.008 |
| Pneumothorax† | 2 | (11–21) | 1345 | 0.46 (0.28 to 0.77) | 0% | 0.003 |
| ICU acquired muscle weakness | 3 | (11, 12, 21) | 691 | 1.19 (0.99 to 1.44) | 0% | 0.07 |
| Days not in the ICU at day 28 | 3 | (11, 14, 21) | 1369 | 0.16 (−1.00 to 1.31) | 17% | 0.79 |
| APACHE II score | 2 | (13–28) | 137 | −2.07 (−3.17 to -0.97) | 35% | 2E-04 |
| MRC score | 2 | (11–21) | 1345 | −2.24 (−6.24 to 1.76) | 84% | 0.27 |
| PaO2/FiO2 at 48 hours | 5 | (9, 12–14, 21) | 1218 | 18.91 (4.29 to 33.53) | 59% | 0.01 |
| PaO2/FiO2 at 72 hours | 4 | (9, 11–12, 21) | 1437 | 12.27 (4.65 to 19.89) | 37% | 0.002 |
| Subgroup analysis of 21 to 28 day mortality (PaO2/FiO2) | ||||||
| ARDS with PaO2/FiO2 <200 mm Hg | 1 | (12) | 36 | 0.50 (0.21 to 1.17) | – | 0.58§ |
| ARDS with PaO2/FiO2 <300 mm Hg | 1 | (28) | 41 | 0.35 (0.03 to 3.60) | – | |
| ARDS with PaO2/FiO2 <150 mm Hg | 4 | (9, 11, 13, 21) | 1497 | 0.75 (0.54 to 1.02) | 62% | |
| Subgroup analysis of 21–28 days mortality (prone position) | ||||||
| Did not used prone position in both group | 2 | (9–12) | 92 | 0.56 (0.35,0.90) | 0% | 0.13§ |
| Used prone position in both group | 4 | (11, 13, 21, 28) | 1386 | 0.86 (0.64,1.16) | 45% | |
| Subgroup analysis of 21–28 days mortality (whether used lighter sedation in control group) | ||||||
| Used lighter sedation in control group | 2 | (21–28) | 1047 | 0.98 (0.84 to 1.16) | 0% | 0.005§ |
| Used deep sedation in control group | 4 | (9, 11–13) | 1574 | 0.63 (0.49 to 0.82) | 0% | |
| Sensitive analysis | ||||||
| 90 days mortality† | 4 | (9, 11, 14, 28) | 460 | 0.75 (0.56 to 1.00) | 13% | 0.05 |
| 21–28 days mortality‡ | 5 | (9, 11–13, 28) | 568 | 0.63 (0.48 to 0.81) | 0% | 4E-04 |
| PaO2/FiO2 at 48 hours‡ | 4 | (9, 12–14) | 1182 | 13.08 (0.96 to 25.20) | 46% | 0.03 |
Barotrauma is defined as any new pneumothorax, pulmonary mediastinum, subcutaneous emphysema or pulmonary bulge larger than 2 cm in diameter.
*Pneumothorax refers to the entry of gas into the pleural cavity, causing a state of pneumothorax, called pneumothorax.
†Sensitive analysis of primary outcome.
‡Sensitive analysis of secondary outcomes.
§ Values of test of interaction between subgroups.
APACHE II, Acute Physiology and Chronic Health Evaluation II; FiO2, fractional inspired oxygen; ICU, intensive care unit; MD, mean difference; MRC score, The Medical Research Council score; PaO2, arterial oxygen tension; RR, risk ratio.