Table 3.
Odds Ratios for Associations between ZIP code-level percent poverty or African American with 1991–2010 Alabama low birth weight by population density tertile
| |
Population density |
||
|---|---|---|---|
| 1st tertile | 2nd tertile | 3rd tertile | |
| Model 1: Poverty*population density (interaction P-value = 0.0043) | |||
| 1st quartile |
1.00 |
1.00 |
1.00 |
| 2nd quartile |
1.15 (1.04, 1.27) |
1.10 (1.01, 1.20) |
1.31 (1.15, 1.49) |
| 3rd quartile |
1.28 (1.16, 1.41) |
1.25 (1.13, 1.37) |
1.47 (1.28, 1.68) |
| 4th quartile |
1.54 (1.39, 1.70) |
1.42 (1.25, 1.62) |
1.79 (1.62, 1.98) |
| Model 2: Poverty*population density (interaction P-value = 0.0010) | |||
| 1st quartile |
1.00 |
1.00 |
1.00 |
| 2nd quartile |
1.14 (1.05, 1.23) |
1.00 (0.94, 1.06) |
1.08 (0.99, 1.17) |
| 3rd quartile |
1.14 (1.06, 1.23) |
1.03 (0.96, 1.09) |
1.04 (0.96, 1.13) |
| 4th quartile |
1.05 (0.97, 1.13) |
0.96 (0.88, 1.05) |
1.12 (1.05, 1.19) |
| Model 1: African American*population density (P-value = 0.0099) | |||
| 1st quartile |
1.00 |
1.00 |
1.00 |
| 2nd quartile |
1.08 (1.01, 1.15) |
1.07 (0.99, 1.15) |
1.14 (0.96, 1.37) |
| 3rd quartile |
1.26 (1.18, 1.35) |
1.27 (1.16, 1.38) |
1.51 (1.27, 1.78) |
| 4th quartile |
1.56 (1.46, 1.67) |
1.64 (1.43, 1.87) |
2.06 (1.76, 2.42) |
| Model 2: African American*population density (P-value = 0.13) | |||
| 1st quartile |
1.00 |
1.00 |
1.00 |
| 2nd quartile |
0.98 (0.93, 1.04) |
0.98 (0.93, 1.04) |
1.05 (0.92, 1.21) |
| 3rd quartile |
0.97 (0.92, 1.03) |
1.00 (0.94, 1.07) |
1.12 (0.99, 1.28) |
| 4th quartile | 0.94 (0.89, 1.00) | 0.98 (0.89, 1.09) | 1.13 (1.00, 1.28) |
Model 1 includes ZIP code-level poverty or African American, population density tertile, and interaction term for the ZIP-level variable and population density tertile, adjusted for year with a B-spline.
Model 2 includes model 1 variables adding parity, payment method, education, race, and a natural spline for mother’s age.