Table 1

SES characteristics and Salmonella infection at the block group level. Socioeconomic and demographic predictors of Salmonella infections at the block group level in a tri-county area of Michigan (1997–2006): results of a multivariable Poisson regression model. (n = 3,419)

Variable

Block groups # (%)

Un-adjusted RR (95% CI)

Adjusted RR (95% CI)

Education attainment (aged ≥ 25 years) at block group level

College degree and above

581 (16.99)

Reference

Reference

High school degree, some college education but no degree

2667 (78.01)

0.79 (0.73, 0.86)

0.84 (0.76, 0.92)*

None to less than a high school degree

171 (5.00)

0.74 (0.61, 0.90)

0.71 (0.65, 1.00)*

Annual median household income at block group level (highest to lowest)

4^th quartile (≥ $ 60,000)

965 (28.22)

Reference

Reference

3^rd quartile ($ 47,000 – < $60,000)

734 (21.47)

0.94 (0.86, 1.35)

0.99 (0.89, 1.10)

2^nd quartile ($33,000 – < $ 47,000)

880 (25.74)

0.80 (0.73, 0.88)

0.86 (0.77, 0.97)*

1^st quartile (< $ 33,000)

840 (24.57)

0.82(0.75, 0.91)

0.91 (0.79, 1.04)

Race at block group level (based on the largest proportion)

Caucasian, predominantly

2337 (68.35)

Reference

Reference

African American, predominantly

997 (29.16)

0.87 (0.80, 0.95)

0.94 (0.84, 1.05)

Other, predominantly

85 (2.49)

0.91 (0.73, 1.13)

0.96 (0.76, 1.22)

Area of residence at block group level (based on US Bureau of Census definition)

Rural, predominantly

27 (0.79)

Reference

Reference

Urban-rural mixed

107 (3.13)

1.18 (1.30, 1.80)

1.13 (0.74, 1.74)

Urban, predominantly

3285 (96.08)

1.15 (0.77, 1.74)

1.19 (0.79, 1.78)

*Significant at 0.05 in the adjusted model; RR: rate ratios; CI: confidence interval.

Final Poisson regression model was adjusted for median age, median income, education level, race, and area of residence at the block group level

Younus et al. International Journal of Health Geographics 2007 6:56   doi:10.1186/1476-072X-6-56