Table 2 GRADE summary of findings table of primary outcomes

Non-intubated patients

Mortality

RCT

224 per 1000

204 per 1000 (175–238)

RR 0.91 (0.78–1.06)

2404 (8)

⨁⨁⨁⨁ High

NRS

314 per 1000

176 per 1000 (141–220)

RR 0.56 (0.45–0.70)

3361 (18)

⨁◯◯◯ Very low^a

Need for intubation

RCT

389 per 1000

315 per 1000 (280–351)

RR 0.81 (0.72–0.90)

2156 (7)

⨁⨁⨁⨁ High

NRS

412 per 1000

267 per 1000 (206–350)

RR 0.65 (0.50–0.85)

3374 (18)

⨁◯◯◯ Very low^a

Adverse events

RCT

24 per 1000

23 per 1000 (16–34)

RR 0.97 (0.66–1.43)

7011 (6)

⨁⨁⨁◯ Moderate^b

NRS

Cases in the prone group were reported as follows: desaturation or hemodynamic worsening 0/30 [34], back pain 2/30 [34] and 3/57 [42], bloating sensation 2/30 [34], gastric distension and vomit 0/81 [30], peripheral line removal 2/57 [42] and 2/81 [30], nasal skin ulceration 2/81 [30], major adverse events 0/48 [44], overall adverse events 0/17 [5] and 0/38 [46]

716 (6)

⨁◯◯◯ Very low^a,b

Intubated patients

Mortality

NRS

525 per 1000

504 per 1000 (441–573)

RR 0.96 (0.84–1.09)

995 (2)

⨁◯◯◯ Very low^a

Chen et al. [38] reported better survival in prone group than in non-prone group (adjusted hazard ratio 0.282, 95% CI 0.126 to 0.63)

40 (1)

Adverse events

NRS

Cases in the prone group were reported as follows: endotracheal tube dislocation 0/62 [9], peripheral line removal 2/62 [9]

261 (1)

⨁◯◯◯ Very low^a,b