Table 3.
Associations of Distance to Major Roadways and 2003 Annual Average PM2.5 Concentration With Prevalence of Hepatic Steatosisa Among Participants From the Multi-Detector Computed Tomography Study, Boston, Massachusetts, 2002–2005
| Exposure | Model 1b | Model 2c | Model 3d | |||
|---|---|---|---|---|---|---|
| PR | 95% CI | PR | 95% CI | PR | 95% CI | |
| PM2.5 concentratione | 0.98 | 0.90, 1.05 | 0.96 | 0.89, 1.05 | 0.97 | 0.89, 1.06 |
| Loge distancef | 1.19 | 1.07, 1.32 | 1.16 | 1.05, 1.28 | 1.16 | 1.05, 1.28 |
| Distance category, m | ||||||
| <50.0 | 1.31 | 1.01, 1.69 | 1.20 | 0.93, 1.55 | 1.21 | 0.94, 1.55 |
| 50.0–99.9 | 1.48 | 1.08, 2.02 | 1.43 | 1.04, 1.96 | 1.44 | 1.05, 1.98 |
| 100.0–199.9 | 1.14 | 0.86, 1.52 | 1.08 | 0.81, 1.44 | 1.09 | 0.81, 1.46 |
| 200.0–399.9 | 1.00 | 0.76, 1.31 | 0.93 | 0.71, 1.23 | 0.95 | 0.72, 1.25 |
Abbreviation: CI, confidence interval; MDCT, multidetector computed tomography; PM2.5, particulate matter having an aerodynamic diameter of ≤2.5 μm; PR, prevalence ratio.
a Defined as a liver-to-phantom ratio of ≤0.33.
b Model 1 adjusted for age at MDCT scan, (age at MDCT scan)2, sex, and an exam identifier.
c Model 2 included the model 1 covariates plus cigarette-smoking status (current, former, or never), pack-years of smoking, alcohol intake, educational level, usual occupation, physical activity, antihypertensive medication use, statin use, quartile of median household income in the participant's census tract in 2000, median value of owner-occupied housing units in the census tract, and population density (population/km2) in the census tract.
d Model 3 included the model 2 covariates plus cardiovascular disease and diabetes.
e Scaled to be equivalent to per-1.4-μg/m3 increase in 2003 annual PM2.5 concentrations.
f Scaled to approximate comparing participants who lived 58 m (25th percentile) from the nearest major roadway with those who lived 416 m (75th percentile) from the nearest major roadway.