Table 3. Univariable and multivariable negative binomial regression model assessing variation in incident encephalitis hospitalizations, Ontario, Canada, and England*.

Variable	No. (%) cases, N = 6,463	Incidence rate	Multivariable analysis
			Ontario, 2002–2013			England, 2005–2009†
			Adjusted IRR (95% CI)	p value		Adjusted IRR (95% CI)	p value
Sex
M	3,417 (52.8)	4.6	Referent	<0.0001		Referent	0.002
F	3,046 (47.1)	4.0	0.9 (0.8–0.9)			0.9 (0.9–1.0)
Age group, y
<1	173 (2.7)	10.7	3.9 (3.3–4.5)	<0.0001		3.7 (3.2–4.2)	<0.001
1–4	377 (5.8)	5.7	2.1 (1.8–2.3)			1.9 (1.7–2.1)
5–19	915 (14.2)	3.2	1.2 (1.1–1.3)			0.9 (0.8–1.0)
20–44	1,486 (23.0)	2.8	Referent			Referent
45–64	1,823 (28.2)	4.4	1.6 (1.5–1.8)			1.4 (1.3–1.5)
>65	1,689 (26.1)	8.3	3.0 (2.8–3.2)			1.9 ( 1.8–2.1)

*Incidence is number of cases/100,000 persons. IRR, incident rate ratio.
†Reference (1).