Table 4

Mortality

	Inpatient mortality:				Fishers Exact test (NIV versus not NIV	90-day mortality^*				Fishers Exact test (NIV versus not NIV
	For ALL Patients not receiving NIV		For ALL Patients receiving NIV			For ALL Patients not receiving NIV		For ALL Patients receiving NIV
	%	N	%	N		%	N	%	N
ALL PATIENTS	5	475/8639	25	270/1077	<0.001	11	949/8269	33	340/1031	<0.001
Acidotic patients	14	165/1174	26	249/969	<0.001	22	246/1143	33	310/932	<0.001
Non-acidotic patients	4	246/5994	10	8/78	0.02	10	558/5727	21	15/73	0.005
No admission gases	4	64/1471	43	13/30	<0.001	10	145/1399	58	15/26	<0.001
ACIDOTIC on admission, this being the lowest pH (group 1)	9	70/792	19	82/433	<0.001	16	126/770	30	123/412	<0.001
ACIDOTIC on admission, later lowest pH ALSO ACIDOTIC (group 2)	21	28/136	26	81/317	0.28	32	42/133	31	95/305	0.99
NON-ACIDOTIC on admission, later lowest pH ACIDOTIC (group 3)	27	67/246	39	86/219	0.008	33	78/240	43	92/215	0.03
χ² p value (comparing above 3 groups)	p<0.001		p<0.001			p<0.001		p=0.003

↵* Within 90 days from index admission.