Table 3.
Trace element and source impact IHD mortality hazard ratios per interquartile range (IQR) for alternative Cox proportional hazard model specifications.
| Exposure variable (IQR) | IQR CPH hazard ratio (95% CI) | IQR CPH-RE hazard ratio (95% CI) | ||
|---|---|---|---|---|
| No random effects, no contextual variablesa | No random effects, with contextual variablesa | With random effects, no contextual variablesa | With random effects and contextual variablesa | |
| PM2.5 (3.1347 μg/m3) | 1.04 (1.03, 1.05) | 1.02 (1.01, 1.03) | 1.05 (1.02, 1.08) | 1.03 (1.00, 1.06) |
| As (0.00055 μg/m3) | 1.03 (1.02, 1.04) | 1.04 (1.02, 1.05) | 1.04 (1.01, 1.06) | 1.04 (1.02, 1.06) |
| Ca (0.04382 μg/m3) | 1.02 (1.01, 1.03) | 1.01 (1.00, 1.03) | 1.02 (0.99, 1.05) | 1.01 (0.98, 1.03) |
| Cl (0.03350 μg/m3) | 1.03 (1.02, 1.04) | 1.02 (1.01, 1.03) | 1.03 (1.00, 1.05) | 1.02 (1.00, 1.05) |
| Fe (0.04775 μg/m3) | 1.03 (1.02, 1.04) | 1.02 (1.01, 1.03) | 1.03 (1.00, 1.05) | 1.02 (1.00, 1.05) |
| Pb (0.00259 μg/m3) | 1.03 (1.02, 1.04) | 1.03 (1.02, 1.04) | 1.03 (1.01, 1.04) | 1.03 (1.01, 1.04) |
| Mn (0.00207 μg/m3) | 1.00 (1.00, 1.01) | 1.00 (1.00, 1.01) | 1.00 (0.99, 1.01) | 1.00 (0.99, 1.01) |
| Ni (0.00145 μg/m3) | 1.01 (1.01, 1.02) | 1.01 (1.00, 1.02) | 1.01 (0.99, 1.03) | 1.01 (0.99, 1.03) |
| Se (0.00081 μg/m3) | 1.03 (1.02, 1.04) | 1.03 (1.01, 1.04) | 1.03 (1.01, 1.06) | 1.03 (1.01, 1.06) |
| V (0.00263 μg/m3) | 1.01 (1.00, 1.03) | 1.00 (0.97, 1.01) | 1.01 (0.97, 1.05) | 1.01 (0.97, 1.05) |
| Si (0.04288 μg/m3) | 1.01 (1.00, 1.01) | 0.99 (0.98, 1.01) | 1.00 (0.98, 1.03) | 0.99 (0.97, 1.02) |
| Zn (0.01013 μg/m3) | 1.02 (1.01, 1.02) | 1.01 (1.01, 1.02) | 1.01 (0.99, 1.02) | 1.01 (0.99, 1.02) |
| K (0.02186 μg/m3) | 1.00 (0.99, 1.02) | 1.00 (0.98, 1.01) | 1.00 (0.97, 1.03) | 0.99 (0.96, 1.02) |
| Na (0.03337 μg/m3) | 1.01 (1.01, 1.02) | 1.01 (0.99, 1.02) | 1.01 (0.99, 1.03) | 1.01 (0.99, 1.04) |
| EC (0.25755 μg/m3) | 1.04 (1.03, 1.05) | 1.03 (1.01, 1.04) | 1.03 (1.00, 1.06) | 1.03 (1.00, 1.06) |
| OC (0.97547 μg/m3) | 1.01 (0.99, 1.02) | 0.99 (0.97, 1.00) | 1.00 (0.97, 1.03) | 0.99 (0.96, 1.01) |
| S (0.52882 μg/m3) | 1.02 (1.00, 1.03) | 1.05 (1.02, 1.07) | 1.03 (0.99, 1.07) | 1.06 (1.02, 1.11) |
| Biomass burning (0.54040 μg/m3) | 1.00 (0.99, 1.01) | 1.00 (0.99, 1.01) | 1.00 (0.98, 1.02) | 0.99 (0.98, 1.01) |
| Coal combustion (0.64208 μg/m3) | 1.02 (1.02, 1.03) | 1.02 (1.01, 1.03) | 1.03 (1.01, 1.06) | 1.03 (1.01, 1.05) |
| Steel industryb (0.1 μg/m3) | 1.01 (0.99, 1.03) | 1.01 (0.99, 1.02) | 0.99 (0.95, 1.03) | 1.00 (0.97, 1.03) |
| Oil combustion (1.08574 μg/m3) | 1.01 (1.00, 1.02) | 1.00 (0.99, 1.02) | 1.01 (0.98, 1.04) | 1.01 (0.98, 1.04) |
| Salt aerosols (0.10488 μg/m3) | 1.02 (1.01, 1.02) | 1.01 (1.00, 1.02) | 1.01 (0.99, 1.03) | 1.02 (0.99, 1.04) |
| Traffic-related (2.39980 μg/m3) | 1.03 (1.02, 1.04) | 1.03 (1.01, 1.05) | 1.02 (0.98, 1.05) | 1.03 (0.99, 1.07) |
| Metals-related (0.17518 μg/m3) | 1.01 (1.00, 1.02) | 1.01 (1.01, 1.02) | 1.01 (1.00, 1.03) | 1.02 (1.00, 1.03) |
| Crustal/soil (0.56015 μg/m3) | 1.01 (1.00, 1.02) | 0.99 (0.98, 1.01) | 1.01 (0.98, 1.05) | 1.00 (0.97, 1.03) |
| aAll models include 42 individual-level variables. Random-effects adjustments are at MSA-level. The six ecological contextual variables were obtained from the 1990 U.S. Census (median household income, percentage of persons > 16 years of age who were unemployed, percentage of adults with a postsecondary education, Gini coefficient of income inequality, and percent black and percent Hispanic population). bSteel increment = 0.1; steel IQR = 0.0. | ||||