Table 3.

Analysis of Risk Factors for LOS (n_max = 232)

	Univariate				Multivariate
Risk factors present on admission		Difference in median LOS (hours) *	95%CI	P‐value	Difference in median LOS (hours) *	95%CI	P‐value
Continuous	Spearman correlation
Age (months)	−0.2	−1.2	(−2.1, −0.2)	0.02	−0.6	(−1.6, 0.5)	0.3
Gestational age (weeks)	0.09	0.7	(−0.7, 2.0)	0.3
Birth weight (kg)	0.03	−0.0	(−5.7, 6.2)	0.9
Severity score on admission (points)	0.2	3.1	(1.1, 5.1)	0.002	3.0	(0.7, 5.1)	0.01
Categorical	Geometric mean LOS (hours)
Gender
Female	61	−1.4	(−9.4, 8.0)	0.8
Male	62	(reference)
Currently breastfed
Yes	62	1.9	(−8.9, 15.1)	0.7
No	60	(reference)
Previous respiratory hospitalisation
Yes	60	−2.0	(−11.1, 9.0)	0.7
No	62	(reference)
Mother smoked during pregnancy
Yes	62	1.7	(−6.6, 11.4)	0.7
No	60	(reference)
Exposed to household smoke
Yes	62	0.2	(−8.0, 9.8)	0.9
No	61	(reference)
Antibiotics before hospitalisation
Yes	61	−7.1	(−14.4, 1.4)	0.09	−2.4	(−11, 7.6)	0.6
No	69	(reference)
Any virus detected
Yes	64	8.7	(−1.9, 21.3)	0.11
No	55	(reference)
RSV
Yes	66	7.0	(−2.2, 17.2)	0.14	10.0	(−0.6, 22.3)	0.06
No	58	(reference)
HRV
Yes	64	3.4	(−6.1, 14.6)	0.5
No	61	(reference)
RSV and HRV
Yes	64	5.0	(−3.8, 15.1)	0.3
No	59	(reference)
Adenovirus
Yes	57	−4.4	(−18.3, 14.3)	0.6
No	62	(reference)
Any bacteria detected
Yes	63	3.1	(−5.7, 13.4)	0.5
No	59	(reference)
Virus/bacteria interaction				0.3
Virus negative/Bacteria negative	58	(reference)
Virus negative/Bacteria positive	53	−5.0	(−19.1, 14.2)	0.6
Virus positive/Bacteria negative	60	1.5	(−13.2, 21.0)	0.9
Virus positive/Bacteria positive	65	7.0	(−7.9, 26.0)	0.4

On univariate analysis, factors at enrolment associated with prolonged LOS were age and severity score. On multivariate analysis, only severity score remained significant.

^* Arising as a re‐expression of the multiplicative effect on the geometric mean from a linear regression on log (LOS).