Table 4. Result of multivariate logistic regression analysis in relation to HFRS occurrence in China, 1994–1998*.

	p value	OR (95% CI)
Elevation, m
<100	–	1.00
100–200	0.75	0.93 (0.61–1.43)
201–500	0.47	0.87 (0.59–1.28)
501–1,000	<0.01	0.58 (0.39–0.86)
1,001–1,500	<0.01	0.27 (0.17–0.43)
1,501–2,000	<0.01	0.22 (0.12–0.39)
2,001–3,000	<0.01	0.31 (0.16–0.60)
>3,000	<0.01	0.05 (0.01–0.25)
NDVI	<0.01
<0.1	–	1.00
0.1–0.2	0.73	1.12 (0.60–2.11)
0.2–0.3	0.25	1.44 (0.77–2.69)
>0.3	0.22	0.64 (0.32–1.29)
Precipitation, mm/y	<0.01
<400	–	1.00
400–800	<0.01	9.94 (3.92–25.23)
801–1,200	<0.01	8.16 (2.97–22.44)
>1,200	<0.01	4.95 (1.70–14.39)
Annual cumulative air temperature, °C	<0.01
<1,600	–	1.00
1,600–3,400	<0.01	0.47 (0.28–0.79)
3,401–4,500	0.41	1.25 (0.73–2.15)
4,501–8,000	0.17	1.58 (0.82–3.07)
>8,000	0.14	2.76 (0.71–10.72)
Soil or land-use type
Ferralisol	<0.01	0.65 (0.46–0.90)
Desert	<0.01	0.59 (0.41–0.84)
Skeletol primitive	<0.01	0.66 (0.50–0.88)
Semihydromorphic	<0.01	1.53 (1.14–2.06)
Alpine	<0.01	0.23 (0.07–0.73)
Timber forest	<0.01	2.04 (1.48–2.81)
Orchard	<0.01	1.97 (1.18–3.29)
Sparse woods	<0.01	0.60 (0.46–0.78)
Bare land	0.02	0.45 (0.23–0.87)

*HFRS, hemorrhagic fever with renal syndrome; NVDI, normalized difference vegetation index; OR, odds ratio; CI, confidence interval.