Table 4.
Percent difference (95% CI) in three arterial stiffness outcomes per 10-μg/m3 PM increment in preceding two decades and 2001 PM exposure under various covariate adjustment schemes: MESA, 2000–2002.
| PM exposure in preceding two decades
|
2001 PM exposure
|
||||
|---|---|---|---|---|---|
| Outcome/covariates | Observed PM10 | Imputed PM10 | Imputed PM2.5 | PM10 | PM2.5 |
| YM
| |||||
| PM (weather/season only)a | 3.5 (−2.5 to 9.8) | 5.2 (−0.3 to 11.0) | 0.4 (−3.6 to 4.6) | −0.2 (−0.8 to 0.4) | −0.8 (−1.4 to −0.3) |
| Add age, sex, race | 2.3 (−3.5 to 8.6) | 3.2 (−2.4 to 9.1) | −0.8 (−4.7 to 3.2) | 0.0 (−0.5 to 0.5) | −0.5 (−1.1 to 0.0) |
| All covariatesb | 1.6 (−3.8 to 7.3) | 3.1 (−1.9 to 8.3) | −1.4 (−5.1 to 2.4) | 0.0 (−0.5 to 0.5) | −0.5 (−1.1 to 0.0) |
| C1 | |||||
| PM (weather/season only)a | 2.7 (−2.4 to 8.1) | 0.7 (−5.0 to 6.7) | −0.2 (−3.0 to 2.6) | −0.2 (−0.6 to 0.3) | −0.6 (−1.5 to 0.2) |
| Add age, sex, race | 2.9 (−1.6 to 7.7) | 2.6 (−2.2 to 7.7) | 1.7 (−0.9 to 4.3) | −0.2 (−0.5 to 0.2) | 0.0 (−0.8 to 0.8) |
| All covariatesb | 2.9 (−1.8 to 7.7) | 2.6 (−2.3 to 7.8) | 1.5 (−1.0 to 4.1) | −0.2 (−0.5 to 0.2) | 0.0 (−0.8 to 0.8) |
| C2 | |||||
| PM (weather/season only)a | −1.8 (−6.9 to 3.5) | −3.9 (−9.6 to 2.1) | −3.7 (−8.0 to 0.8) | 0.3 (−0.3 to 0.8) | 0.6 (−0.2 to 1.4) |
| Add age, sex, race | −3.3 (−8.0 to 1.6) | −1.4 (−6.5 to 3.9) | −0.7 (−4.6 to 3.3) | 0.1 (−0.4 to 0.6) | 0.2 (−0.6 to 1.0) |
| All covariatesb | −3.6 (−8.2 to 1.3) | −1.5 (−6.5 to 3.8) | −1.2 (−5.0 to 2.7) | 0.1 (−0.3 to 0.5) | 0.2 (−0.6 to 1.0) |
Regression results are reported as percent differences (95% CIs) in outcome variables [100 × (exponentiated mean difference − 1)] for each metric and outcome, pooled over all study sites using random effects regression. A positive point estimate for YM indicates greater arterial stiffness with higher exposure; a negative point estimate for C1 and C2 indicates reduced compliance with higher exposure. PM levels are from the nearest monitor or space–time model (see Table 2).
Weather and season terms included in all models: apparent temperate spline with 3 degrees of freedom, interacted with site; and indicator variables to represent months with average monthly temperature above 10°C (50°F) during baseline recruitment period (all year for Los Angeles; May–October for Chicago and St. Paul; April–October for remaining three sites).
All covariates for YM are age, sex, race, fasting blood glucose, triglycerides, diabetes, seated MAP, smoking status, pack-years, cigarettes per day, ETS exposure, physical activities, waist:hip ratio, season, and weather. For C1 and C2, in addition, height, weight, and heart rate were included.