Abstract 058: Residential Proximity to Major Roadways is Associated with Increased Risk of Hypertension among Post-Menopausal Women: Results from the San Diego Cohort of the Women's Health Initiative
Authors: Kipruto Kirwa, Yi Wang, Marc A Adams, Cindy G Morgan, Jaqueline Kerr, Gregory J Norman, Charles B Eaton, Matthew A Allison, Gregory A Wellenius
Journal: Circulation (2012)

Introduction: Long term exposure to traffic pollution has been linked to elevated risk of cardiovascular events and mortality. These associations may be conceptually mediated, at least in part, through increased risk of hypertension, but this hypothesis has not been examined in detail. We assessed the hypothesis that residential distance to major roadways, a marker of long-term exposure to traffic pollution, is inversely associated with risk of hypertension among post-menopausal women. Methods: We examined the cross-sectional association between residential proximity to major roadways and prevalent hypertension using baseline data from 5,401 women aged 50–79 years enrolled into the San Diego cohort of the Women’s Health Initiative. We geocoded participants’ residential addresses and calculated the Euclidean distance to the nearest freeway, freeway ramp or prime arterial road. Hypertension was defined as blood pressure ≥140/90 mmHg, self-reported history of anti-hypertensive drug use or prior physician diagnosis. We used logistic regression to estimate the association between hypertension prevalence and distance to major roadway, adjusting for age, race, smoking, body mass index, waist-hip ratio, history of diabetes, cholesterol level, education, family income, and neighborhood socioeconomic status. We considered distance to major roadway as both a categorical variable (≤50, &gt;50 to 200, &gt;200 to 400, and &gt;400 m) and a log-transformed continuous variable. In a sensitivity analysis, we further adjusted for density of supermarkets and grocery stores within 1.6 km of each residence. Results: Participants were predominantly white non-Hispanic (75.4%) with a mean age of 64.7 (SD=7.7) years. The prevalence of hypertension was 42.0%. The median distance to a major roadway was 837 m (25 th − 75 th percentiles: 408 – 1510 m). Adjusting for individual characteristics and individual and neighborhood level indicators of socioeconomic status, the prevalence odds ratio for hypertension was 1.69 (95% CI: 1.11, 2.59), 1.11 (0.89, 1.38) and 1.06 (0.89, 1.26) for women living ≤50, &gt;50 to 200, and &gt;200 to 400 versus &gt;400 m from a major roadway ( P trend =0.03). Considering distance to major roadway as a log-transformed continuous variable, we found that living 400 m versus 1500 m from a major roadway was associated with a 8.3% (95% CI: 1.9, 15.1%) increase in the prevalence odds of hypertension ( P= 0.01). Further adjustment for local supermarket/grocery store density did not materially alter the results. Conclusion: In this cohort of post-menopausal women, residential proximity to major roadways was associated with prevalence of hypertension, even after accounting for important individual, socioeconomic and neighborhood-level characteristics. These results suggest that traffic pollution may increase the risk of cardiovascular events, at least in part, through increased risk of hypertension.