Table 2.

Influenza Vaccination and Severity of Influenza Disease Analysis for Cases Treated With Antivirals by Age Category, After Propensity Score Matching (n = 1509)^a

Clinical Outcomes	Influenza Vaccine 2012–13 Season
	50–64 y (n = 494)		65–74 y (n = 495)		≥75 y (n = 520)
	Point Estimate (95% CI)	P Value	Point Estimate (95% CI)	P Value	Point Estimate (95% CI)	P Value
Severe diseaseb (OR)	0.97 (.62; 1.52)	.89	1.27 (.81; 1.99)	.29	0.99c (.59; 1.66)	.97
Diagnosis of pneumoniad (OR)	0.79 (.54; 1.18)	.25	0.86c (.59; 1.26)	.44	0.94c (.65; 1.35)	.72
ICU length of stay (RH)e	1.25 (.82; 1.91)	.3	1.60 (1.04; 2.46)	.03	0.94 (.50; 1.77)	.85
Length of hospital stay (RH)e	1.03 (.88; 1.21)	.69	1.03 (.88; 1.21)	.68	1.02 (.87; 1.19)	.80

Abbreviations: BMI, body mass index; CI, confidence interval; ICU, intensive care unit; OR, odds ratio; RH, relative hazard.

^aVariables used for propensity score matching: sex, race, BMI, medical condition (asthma, chronic lung disease, cardiovascular disease, chronic metabolic disease, neurologic disease, immunosuppression, hemoglobinopathy/blood disorders, renal disease, liver disease), alcohol abuse, and smoking.

^bAdmitted to ICU or deceased.

^cAdjusted for the Charlson score.

^dAmong those who had a chest X-ray taken within 3 days of admission (n = 1,460).

^eRH represents ICU or hospital discharge accounting for death as a nonindependent competing risk.