Table 5.

Risk factors associated with length of stay in Australian children hospitalized with laboratory-confirmed influenza during 2011–2013 at the Children's Hospital at Westmead (NSW, Australia) and Princess Margaret Hospital (WA, Australia) excluding nosocomial cases with onset of symptoms >7 days after admission

Predictor variable	Unadjusted OR of means (95% CI)	P value	Adjusted OR of means (95% CI)	P value
Female sex	1·27 (1·08–1·49)	0·004	1·22 (1·02–1·44)	0·03
CXR abnormality	1·65 (1·40–1·95)	<0·001	1·50 (1·25–1·79)	<0·001
Bacterial co-infection	2·31 (1·83–2·92)	<0·001	2·46 (1·93–3·14)	<0·001
Viral co-infection	1·64 (1·34–2·01)	<0·001	1·72 (1·38–2·15)	<0·001
Febrile seizures	0·48 (0·33–0·68)	<0·001	0·62 (0·42–0·89)	0·01
Afebrile seizure	1·64 (1·10–2·44)	0·02	NI	NI
Encephalitis/encephalopathy	1·56 (0·80–3·03)	0·19	2·47 (1·24–4·90)	0·01
Respiratory comorbidity	1·58 (1·22–2·03)	<0·001	1·40 (1·06–1·84)	0·02
Prematurity	1·54 (1·17–2·02)	0·002	1·45 (1·08–1·94)	0·01
Cardiac comorbidity	1·38 (1·01–1·89)	0·05	NI	NI
Diabetes	1·75 (0·80–3·85)	0·16	2·22 (1·00–4·96)	0·05
Renal comorbidity	1·60 (1·04–2·47)	0·03	1·89 (1·20–2·98)	0·006
Hepatic comorbidity	3·91 (2·39–6·42)	<0·001	5·60 (3·37–9·31)	<0·001
Genetic comorbidity	1·63 (1·20–2·23)	0·002	1·45 (1·04–2·03)	0·03
Metabolic comorbidity	1·48 (0·84–2·60)	0·17	NI	NI

OR, Odds ratio; CI, confidence interval; NI, variable not included in final model after backwards stepwise elimination.

Generalized linear regression model with negative binomial distribution. Predictor variables with P < 0·20 on univariate analysis listed and incorporated into a final multivariate model.