Table 4. Univariable and multivariable Poisson regression model and incidence rate ratio (IRR) of the frequency of URI.

Univariable models	IRR	95% CI	p-value
Intake year 2011(n = 189)	4.00	3.00–5.40	<0.001
Parturition (n = 99)	0.42	0.26–0.68	<0.001
Number of drugs (n = 153)
1 to 4 (n = 92)	1.00
5 to 8 (n = 42)	2.64	1.86–3.75	<0.001
9 or more (n = 19)	5.41	3.67–7.97	<0.001
Number of antibiotics (n = 122)
1 (n = 59)	1.00
2 (n = 33)	1.22	0.84–1.76	0.299
3 or more (n = 30)	2.33	1.61–3.40	<0.001
Steroids (n = 189)	1.74	1.30–2.34	<0.001
Antihistamine (n = 175)	4.24	1.15–1.74	<0.001
Interferon (n = 189)	3.14	2.35–4.20	<0.001
Days under medication (n = 122)
1 week (n = 79)	1.00
2 weeks (n = 23)	2.51	1.69–3.74	<0.001
3 weeks (n = 9)	3.01	1.74–5.22	<0.001
4 weeks or more (n = 11)	3.03	1.72–5.33	<0.001
Multivariable model (n = 175)
Intake year (2011)	3.81	2.59–5.62	<0.001
Antihistamine	1.46	0.99–2.16	0.058
Steroids	1.68	1.25–2.27	0.002