Table 2.

Risk ratios and 95% confidence intervals for independent associations between different variables and missed norovirus cases^a

Variable	Category	No. of patients	Univariate analysis		Multivariate analysis
			OR	95% CI	OR	95% CI
Gender	Female	49	Ref		Ref
	Male	46	2.1	0.9–4.7	NS
Age (yr) by category	All	95	1.01	1.00–1.03	0.95	0.91–0.98
	<18	36	Ref
	≥18	59	4.7	1.9–11.8
Hospital visit due to acute GE (5 not diagnosed)	No	45	Ref		Ref
	Yes	45	0.4	0.1–1.5	NS
Admission duration (days) (1 not diagnosed)	0 (outpatients)	16	Ref		Ref
	1–9	38	0.5	0.1–1.7	NS
	>9	40	0.3	0.1–1.0	NS
Group	University adults	45	Ref		Ref
	University children	36	0.3	0.1–0.7	0	0.0–0.2
	Other	14	2.9	0.7–12.0	5.2	1.0–27.7
Symptoms of acute GE (18 missing)	No	7	Ref		Ref
	Yes	70	0.3	0.1–1.7	NS
Diarrhea (19 not diagnosed)	No	9	Ref		Ref
	Yes	67	0.2	0.0–1.1	0.1	0.0–0.8
Abdominal examination	No	82	Ref		Ref
	Yes	13	4.5	1.1–17.5	11.7	2.3–58.0
Kidney failure	No	82	Ref		Ref
	Yes	13	0.3	0.1–1.1	NS

^aPatients were in a hospital population from 16 December 2008 to 30 June 2009. Values are from univariate and multivariate logistic regression analyses. Boldface indicates a statistically significant difference. Ref, reference category; NS, not significant.