Table 2.

Univariate analysis of risk factors for human infection with avian influenza A(H7N9) virus in Shanghai, China, 2013

Variables	Variable level	Cases n (%)	Controls n (%)	OR (95% CI)	P value
Chronic disease	Yes	18 (72·0)	36 (48·0)	2·7 (1·04–7·45)	0·037*
Body mass index	<20	3 (12·0)	8 (10·7)	Reference
	20–25	12 (48·0)	45 (60·0)	0·7 (0·16–3·10)	0·650
	⩾25	10 (40·0)	22 (29·7)	1·2 (0·26–5·56)	0·804
Frequent hand-washing	No	5 (20·0)	9 (12·0)	1·8 (0·55–6·10)	0·323
Having ever smoked	Yes	10 (40·0)	33 (44·0)	0·8 (0·34–2·13)	0·727
Direct contact with poultry in the live poultry market	Yes	3 (12·0)	11 (14·7)	1·1 (0·57–2·22)	0·740
Preparing or cooking at home†	Yes	4 (16·0)	9 (12·0)	1·4 (0·39–5·00)	0·608
Occupational contact with poultry†	Yes	2 (8·0)	1 (1·3)	6·4 (0·56–74·24)	0·136
Raising poultry or pigeons at home†	Yes	3 (12·0)	3 (4·0)	3·2 (0·62–17·24)	0·160
Indirect contact with poultry at home	Yes	5 (20·0)	4 (5·3)	4·4 (1·09–18·18)	0·038*
Raising poultry or pigeons in the neighbourhood‡	Yes	11(44·0)	31 (41·3)	0·9 (0·36–2·24)	0·815
Visiting a live poultry market‡	No	9 (36·0)	51 (68·0)	Reference
	1–9 times	12 (48·0)	20 (26·7)	3·4 (1·24–9·31)	0·017*
	⩾10 times	4 (16·0)	4 (5·3)	5·6 (1·20–26·87)	0·029*
Visiting a temporary roadside poultry vendor‡	Yes	4 (16·0)	2 (2·7)	6·95 (1·19–40·63)	0·031*
Travel history§	Yes	6 (24·0)	9 (12·0)	2·32 (0·73–7·33)	0·153

OR, Odds ratio; CI, confidence interval.

^†Direct contact with poultry.

^‡Environment-related exposure.

^§Travel to another city where H7N9 cases were reported.

^*P < 0·05