Table 1.

 The relationship between presence of SARS cases and travel‐related risk factors for the 345 counties of three provinces nearby Beijing: Hebei, Shanxi and Inner Mongolia Autonomous Region. Analyses were based on logistic regression, and corrected for population density and medical staff density

Risk factors	Number of counties	Number of counties with SARS cases (%)	Univariate analysis		Multivariate analysis
			Crude OR (95% CI)	P‐value	Adjusted OR (95% CI)	P‐value
Intersected by national highway
No	99	14 (14.1%)	1.00	–	1.00	–
Yes	246	76 (30.9%)	2.71 (1.45–5.08)	0.002	1.95 (1.01–3.75)	0.046
Intersected by railway
No	132	22 (16.7%)	1.00	–
Yes	213	68 (31.9%)	2.34 (1.37–4.03)	0.002	Not significant and excluded
Intersected by inter‐provincial freeway
No	247	50 (20.2%)	1.00	–	1.00	–
Yes	98	40 (40.8%)	2. 72 (1.63–4.52)	<0.001	1.89 (1.06–3.36)	0.031
Medical staff density (categorical)
0.1–0.9 per 1000 persons	94	20 (21.3%)
0.9–1.2 per 1000 persons	75	18 (24.0%)
1.2–1.8 per 1000 persons	87	23 (26.4%)
1.8–23 per 1000 persons	89	29 (32.6%)
Medical staff density (continuous, per 100 persons)			8.90 (1.66–47.75)	0.011	4.61 (0.92–23.13)	0.064
Population density (categorical)
1–70 per km2	85	11 (12.9%)
70–200 per km2	82	22 (26.8%)
200–600 per km2	104	28 (26.9%)
600–54 000 per km2	74	29 (39.2%)
Population density (continuous, 1000 per km2)			2.93 (1.63–5.27)	<0.001	2.21 (1.22–4.00)	0.009