. 2015 Jun 21;15:241. doi: 10.1186/s12913-015-0917-x

Table 3.

Healthcare resource utilization for ICU patients with S. aureus or P. aeruginosa pneumonia versus controls during index hospitalization

	Cohorts of interest			S. aureus pneumonia vs No pneumonia		P. aeruginosa pneumonia vs No pneumonia
	No pneumonia	S. aureus pneumonia	P. aeruginosa pneumonia	Odds Ratio/Difference^a	P Value^a	Odds Ratio/Difference^b	P Value^b
	No pneumonia	S. aureus pneumonia	P. aeruginosa pneumonia	(95 % CI)		(95 % CI)
	N = 201,394	N = 2275	N = 1007	(95 % CI)		(95 % CI)
Mean (SD) length of hospital stay per patient	7.2 (9.6)	37.9 (39.4)	55.4 (54.9)	30.69 (29.41, 32.00)	<.001	48.18 (45.43, 51.08)	<.001
Mean (SD) length of ICU/CCU stay per patient	1.1 (2.1)	6.9 (21.1)	14.8 (36.6)	5.75 (5.59, 5.91)	<.001	13.63 (13.21, 14.06)	<.001
No. (%) of patients with mechanical ventilation	14,960 (7.4)	1,425 (62.6)	627 (62.3)	20.89 (19.16, 22.78)	<.001	20.56 (18.08, 23.38)	<.001

CI confidence interval, ICU intensive care unit

^aOdds ratio (OR) from Chi-square test is used for categorical variables, negative binomial models are used to test for differences between means for count variables (number of events and length of stay). Statistical comparisons are comparing Cohort 3 (pneumonia due to S. aureus) with Cohort 1 (no pneumonia, reference group); ie, Difference = mean (Cohort 3) − mean (Cohort 1) and OR = Odds (Cohort 3)/Odds (Cohort 1)

^bOdds ratio (OR) from Chi-square test is used for categorical variables, negative binomial models are used to test for differences between means for count variables (number of events and length of stay). Statistical comparisons are comparing Cohort 4 (pneumonia due to P. aeruginosa) to Cohort 1 (no pneumonia, reference group); ie, Difference = mean (Cohort 4) – mean (Cohort 1) and OR = Odds (Cohort 4)/Odds (Cohort 1)