Table 3.

Risk factors for severe influenza and univariate analysis; n = 267

Variable	Level	N	Total N for variable	%	Odds ratio	Lower95% CI	Upper95% CI	P‐value
Prematurity	Yes	45	180	25.0	2.3	0.7	7.7	.17
Birthweight	<2.5 kg	25	130	19.2	2.7	0.6	12.3	.19
Gender	Male	149	267	55.8	1.3	0.5	3.4	.64
	Female	118		44.2	1.0
Age	<2 y old	164	267	61.4	2.3	0.7	7.2	.15
	≥2 y old	103		38.6	1.0
Aboriginal/Torres Strait Islander	Yes	25	267	9.4	0.6	0.1	4.3	.57
Weight for age	≥95th centile	23	267	8.6	2.2	0.6	8.3	.25
	85–94th centile	26		9.7	0.6	0.1	4.6	.61
	<85% centile	218		81.7	1.0
Co‐infection	Viral/bacterial	107	267	40.2	1.2	0.5	3.2	.70
Hospital episode number	>1	179	267	67.0	0.8	0.2	2.0	.58
	1	88		33.0	1.0
Influenza strain	Influenza B	54	265	20.4	2.7	1.0	7.4	.05
	Influenza A	211		79.6	1.0
Influenza A subtype	Influenza A non‐H1N1	96	211	45.5	1.5	0.4	5.0	.54
	Influenza A H1N1	115		54.5	1.0
Comorbidities b	Yes	126	267	47.2	1.8	0.7	4.9	.23
Chronic lung disease	Yes	65	267	24.3	1.3	0.5	4.1	.55
Cardiac abnormality	Yes	20	267	7.5	2.7	0.7	10.4	.14
Renal disease	Yes	7	267	2.6	2.4	0.3	20.2	.43
Immunocompromisedc	Yes	15	267	5.6	–	–	–	–
Iron deficiency anaemia	Yes	18	267	6.7	4.2	1.4	12.9	.01
Neurological disorder	Yes	39	267	14.6	2.4	0.8	7.3	.11
Asthma	Yes	42	267	15.7	1.1	0.3	3.9	.91
Atopic historya	Yes	66	267	24.7	1.2	0.4	3.5	.76
Food allergy	Yes	8	267	3.0	5.1	1.0	27.1	.06

^aAtopic history includes asthma, atopic dermatitis and hay fever.

^bAs defined in the AIH.14

^cUnable to fit model as no patients in this category required high‐level care.