Association between hospital case volume and mortality in non-elderly pneumonia patients stratified by severity: a retrospective cohort study

Table 3 Unadjusted and adjusted logistic regression models for the risk of in-hospital mortality for patients with a principal diagnosis of pneumonia, Japanese DPC database, 2010

	Unadjusted analysis				Adjusted model 1				Adjusted model 2
	OR	95% CI		p	OR	95% CI		p	OR	95% CI		p
Hospital case volume (vs. high)
Very low	1.48	1.04	2.10	0.03	1.12	0.90	1.38	0.32	1.02	0.79	1.31	0.88
Low	1.39	0.98	1.96	0.06	1.03	0.83	1.27	0.80	1.13	0.88	1.46	0.34
Medium	1.32	0.92	1.90	0.13	1.06	0.85	1.33	0.59	1.03	0.80	1.32	0.83
Age (year) (vs. 55–64)
18–44					0.43	0.32	0.58	<.001	0.48	0.35	0.67	<.001
45–54					1.24	0.96	1.61	0.10	1.30	0.98	1.73	0.07
Charlson comorbidity index (vs. 0)
1 or 2					1.46	1.05	2.04	0.03	1.35	0.93	1.97	0.11
3–6					3.00	2.03	4.43	<.001	2.59	1.63	4.09	<.001
7 and above					10.37	6.49	16.57	<.001	11.04	6.25	19.49	<.001
Female (vs. male)					1.63	1.24	2.15	<.001	1.38	1.02	1.87	0.04
Referred from clinics/other hospitals (vs. not)					0.97	0.75	1.25	0.80	1.20	0.88	1.63	0.61
Academic hospital (vs. non-academic)					1.13	0.83	1.56	0.44	1.06	0.86	1.31	0.58
Severity indices
BUN ≥21 mg/dL or signs of dehydration									2.44	1.80	3.31	<.001
SpO₂ ≤ 90% (or ≤ PaO₂ 60 Torr)									2.26	1.61	3.16	<.001
Presence of cognitive disturbance									5.85	4.18	8.18	<.001
Systolic blood pressure ≤90 mmHg									2.83	1.97	4.07	<.001

OR: odds ratio; CI: confidence interval.
BUN: blood urea nitrogen; SpO₂: oxygen saturation; PaO₂: arterial oxygen tension.

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