Comparison 2. NIV vs UMC ‐ Admission pH subgroups.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mortality	12		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
1.1 Admission pH > 7.30	5	454	Risk Ratio (M‐H, Fixed, 95% CI)	0.50 [0.30, 0.84]
1.2 Admission pH < 7.30	8	400	Risk Ratio (M‐H, Fixed, 95% CI)	0.57 [0.35, 0.90]
2 Need for endotracheal intubation	17		Risk Ratio (M‐H, Fixed, 95% CI)	Subtotals only
2.1 Admission pH > 7.30	7	589	Risk Ratio (M‐H, Fixed, 95% CI)	0.44 [0.30, 0.63]
2.2 Admission pH < 7.30	11	516	Risk Ratio (M‐H, Fixed, 95% CI)	0.31 [0.22, 0.42]