Table 1.
Characteristics of the included studies.
| Study | Year | Country | Research type | Sample size | Treatment group (PaO2/FiO2, mm Hg) | Control group (PaO2/FiO2, mm Hg) | Primary outcome | Secondary outcome | Score of NOS | Score of Jadad |
|---|---|---|---|---|---|---|---|---|---|---|
| Villar (16) | 2020 | Spain | Randomized controlled trial | 277 | 142.4 ± 37·3 | 143.5 ± 33.4 | Ventilator-free days at 28 days | All-cause mortality 60 days | – | 5 |
| Steinberg (17) | 2006 | USA | Randomized controlled trial | 180 | 126 ± 42 | 126 ± 40 | Mortality at 60 days | Ventilator-free days at 28 days | – | 5 |
| Liu J (18) | 2020 | China | Retrospective study | 774 | 168 (IQR 99–237) | 168 (IQR 99–237) | 28-day all-cause mortality. | In-hospital mortality | 8 | – |
| Bernard (19) | 1987 | USA | Randomized controlled trial | 99 | – | – | Mortality at 45 days | New infection events | – | 5 |
| Annane (20) | 2006 | France | Retrospective study | 177 | 104 ± 42 | 108 ± 45 | Ventilator-free days at 28 days | Mortality in ICU | 7 | – |
| Meduri (21) | 2018 | USA | Retrospective study | 180 | – | – | Mortality at 28 days | New infection events | 8 | – |
| Tongyoo (22) | 2016 | Thailand | Randomized controlled trial | 197 | 175.4 ± 6.9 | 172.4 ± 6.7 | 28-day all-cause mortality | Ventilator-free days at 28 days | – | 5 |
| HS Lee (23) | 2005 | Korea | Retrospective study | 20 | 142.5 ± 23.7 | 143.4 ± 23.9 | In-hospital mortality | Hospital stay days | 7 | – |
| Meduri (24) | 2007 | USA | Randomized controlled trial | 91 | 118.4 ± 51.2 | 125.9 ± 38.6 | Ventilator-free days at 28 days | Mortality in ICU | – | 4 |
| Meduri (25) | 1998 | USA | Randomized controlled trial | 24 | 161 ± 14 | 141 ± 19 | Lung function and mortality | MODS scores | – | 5 |
| Tomazini (26) | 2020 | Brazil | Randomized controlled trial | 299 | 131.1 ± 46.2 | 132.6 ± 45.7 | Ventilator-free days at 28 days | All-cause mortality at 28 days | – | 5 |
| Liu L (40) | 2012 | China | Randomized controlled trial | 26 | 138.2 (87.0, 171.0) | 157.0 (88.7, 176.3) | Mortality at 28 days | New infection events | – | 4 |
| Varpula (27) | 2000 | Finland | Retrospective study | 31 | 126.3 ± 52.4 | 107 ± 41.4 | Mortality at 28 days | New infection events | 7 | – |
| Buisson (28) | 2011 | French | Retrospective study | 208 | 101 (73–174) | 107 (78–144) | In-hospital mortality | New infection events | 9 | – |
| Moss (29) | 2019 | USA | Randomized controlled trial | 1,006 | 98.7 ± 27.9 | 99.5 ± 27.9 | In-hospital mortality | Organ dysfunction | – | 5 |
| Gainnier (30) | 2004 | France | Randomized controlled trial | 56 | 130 ± 34 | 119 ± 31 | Ventilator-free days at 28 days | Mortality in ICU | – | 4 |
| Guervilly (31) | 2016 | France | Randomized controlled trial | 24 | 158 (131; 185) | 150 (121; 187) | Ventilator-free days at 28 days | Mortality in ICU | – | 5 |
| Forel (32) | 2006 | France | Randomized controlled trial | 36 | 105 ± 22 | 125 ± 20 | Mortality at 28 days | Mortality in ICU | – | 4 |
| Papazian (33) | 2010 | France | Randomized controlled trial | 340 | 106.0 ± 36.0 | 115.0 ± 41.0 | The 90-day mortality | The day-28 mortality | – | 5 |
| Lyu (41) | 2014 | China | Randomized controlled trial | 96 | 141.0 ± 26.1 | 144.3 ± 24.1 | Mortality at 28 days | APACHE 1I scores | – | 4 |
| Dellinger (34) | 1998 | USA | Randomized controlled trial | 177 | 135 ± 41.0 | 129.0 ± 38.0 | Ventilator-free days at 28 days | The day-28 mortality | – | 4 |
| Gerlach (35) | 2003 | Germany | Randomized controlled trial | 40 | 113.0 ± 28.0 | 104.0 ± 26.0 | Duration of ventilation | Mortality in ICU | – | 4 |
| Lundin (36) | 1999 | UK | Randomized controlled trial | 268 | 102.8 ± 32.3 | 100.5 ± 33.0 | The day-28 mortality | New infection events | – | 4 |
| Taylor (37) | 2004 | USA | Randomized controlled trial | 385 | 133.0 ± 42.0 | 138.0 ± 43.0 | Ventilator-free days at 28 days | The day-28 mortality | – | 5 |
| Troncy (38) | 1998 | Canada | Randomized controlled trial | 30 | – | – | The day-28 mortality | APACHE II scores | – | 4 |
| Cuthbertson (39) | 2000 | UK | Randomized controlled trial | 30 | – | – | The day-28 mortality | APACHE II scores | 4 |