Table 3.

Effect of demographic and clinical characteristics on laboratory-confirmed influenza type

Variables	Crude		Adjusted*
	OR	95% CI	OR	95% CI
Age group (years)
<=1	Reference group
2 to 4	0.6	0.4 - 1.0	0.6	0.4 - 1.0
5 to 9	0.4	0.2 - 0.6	0.5	0.3 - 0.9
10 to 14	0.3	0.2 - 0.4	0.4	0.3 - 0.7
15 to 24	0.5	0.3 - 0.8	0.8	0.5 - 1.3
25 to 44	0.7	0.5 - 1.1	1.0	0.6 - 1.6
45 to 64	1.1	0.7 - 1.7	1.5	0.9 - 2.5
65 to 74	2.7	1.2 - 6.2	3.1	1.3 - 7.3
75+	2.0	1.4 - 2.8	2.4	1.5 - 3.7
Female	1.0	0.8 - 1.2	0.8	0.7 - 1.0
Resides in an urban area	1.6	1.3 - 1.9	1.3	1.1 - 1.7
Income quintiles
Q1 (lowest)	Reference group
Q2	0.9	0.7 - 1.3	1.0	0.7 - 1.5
Q3	0.6	0.4 - 0.8	0.6	0.5 - 0.9
Q4	0.7	0.5 - 1.1	0.9	0.6 - 1.4
Q5 (highest)	0.8	0.5 - 1.2	1.0	0.6 - 1.5
Unknown	1.5	1.0 - 2.2	1.0	0.6 - 1.5
Asthma	0.9	0.6 - 1.2	0.9	0.6 - 1.3
Any cardiovascular disease	2.2	1.7 - 2.8	0.8	0.5 - 1.1
Chronic obstructive pulmonary disease	1.9	1.3 - 2.6	1.3	0.9 - 1.9
Diabetes	2.2	1.4 - 3.6	1.2	0.7 - 2.0
Immunosuppressed	1.4	1.0 - 1.9	0.8	0.6 - 1.2
Any chronic disease	1.7	1.3 - 2.1	1.0	0.7 - 1.3
Charlson index	1.3	1.1 - 1.4	1.1	1.0 - 1.2
Any hospital admissions in last 5 years	2.2	1.8 - 2.8	1.7	1.3 - 2.3
Had ≥37 physician visits in last 5 years	1.9	1.5 - 2.4	1.0	0.8 - 1.4
Received the seasonal influenza vaccine	1.2	0.9 - 1.7	0.6	0.4 - 0.9
Received a pneumococcal vaccine	1.7	1.3 - 2.1	0.9	0.7 - 1.2

*Final adjusted models included each variable in conjunction with the following covariates: age, sex, locality of residence and income (see text).