Healthcare utilization and costs associated with S. aureus and P. aeruginosa pneumonia in the intensive care unit: a retrospective observational cohort study in a US claims database

Table 2 All-cause mortality of ICU patients with S. aureus or P. aeruginosa pneumonia versus controls

	Cohorts of interest			Comparisons
	Cohorts of interest			S. aureus pneumonia vs No pneumonia		P. aeruginosa pneumonia vs No pneumonia
	No pneumonia (n = 201,394)	S. aureus pneumonia (n = 2275)	P. aeruginosa pneumonia (n = 1007)	Odds Ratio/Difference^a (95 % CI)	P Value^a	Odds Ratio/Difference^b (95 % CI)	P Value^b
Index hospitalization mortality
No. (%) of patients	6,188 (3.1)	363 (16.0)	203 (20.2)	5.99 (5.34, 6.72)	<.001	7.97 (6.81, 9.31)	<.001
Post-index mortality
No. (%) of patients	5,609 (2.8)	227 (10.0)	117 (11.6)	3.87 (3.37, 4.45)	<.001	4.59 (3.78, 5.57)	<.001
Mean (SD) time to death^c	32.8 (27.1)	25.5 (25.8)	28.1 (28.4)	-7.30 (-10.51, -3.63)	<.001	-4.69 (-9.44, 1.02)	.10
Survival rate:				3.75 (3.28, 4.28)	<.001	4.40 (3.66, 5.28)	<.001
30 days (%)	98.5	93.4	92.9
90 days (%)	97.2	90.0	88.4
Index + post-index mortality
No. (%) of patients	11,797 (5.9)	590 (25.9)	320 (31.8)	5.63 (5.11, 6.19)	<.001	7.49 (6.55, 8.56)	<.001
Mean (SD) time to death^c	24.9 (28.3)	46.4 (47.6)	63.5 (59.3)	21.53 (17.39, 26.07)	<.001	38.57 (31.08, 47.07)	<.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) with Cohort 1 (no pneumonia, reference group); i.e., Difference = mean (Cohort 4) − mean (Cohort 1) and OR = Odds (Cohort 4)/Odds (Cohort 1)
^cIncluding only patients with mortality

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