Outcomes	Event rates		RRR (95% CI)†
	Awake prone positioning	Usual care
Endotracheal intubation at 30 d ‡	34%	41%	13% (−7 to 29)
Mortality at 60 d	22%	24%	6% (−33 to 35)
	Mean values		Mean difference (CI)
Ventilation-free§ days at 30 d	21	19	2.04 (−0.50 to 4.59)
Hospital-free days at 60 d	34	31	3.52 (−1.05 to 8.08)
Intensive care unit-free days at 60 d	39	35	4.07 (−0.67 to 8.81)
Adverse events occurred in 10% of patients in the awake prone positioning group vs. 0% in the usual care group; no serious adverse events occurred in either group. In prespecified subgroup analysis, awake prone positioning vs. usual care reduced endotracheal intubation at 30 d in patients with Spo2:Fio2 ratio >150 at baseline (n = 162; 15% vs. 32%; hazard ratio, 0.44 [95% CI, 0.23 to 0.87]) but not in those with Spo2:Fio2 ratio ≤150 (n = 238; Fio2 ratio ≤150 (n = 238; 47% vs. 46%), P for interaction = 0.03; treatment effects did not differ for other subgroups based on age, sex, or respiratory support at baseline.

Abbreviations defined in Glossary. Primary outcome indicated by boldface.

^†RRR and CI calculated using usual care event rates and risk ratio (endotracheal intubation) or hazard ratio (mortality) reported in article.

^‡400 patients were needed to detect an absolute 13.5% reduction in endotracheal intubations with awake prone positioning from 45% with usual care (80% power, 2-sided α = 0.05).

^§Invasive mechanical ventilation or noninvasive ventilation.