Individual and Neighborhood Socioeconomic Status and the Association Between Air Pollution and Cardiovascular Disease

Published in: Environmental Health Perspectives, 2016

Posted on RAND.org on September 13, 2016

by Gloria C. Chi, Anjum Hajat, Chloe E. Bird, Mark R. Cullen, Beth Ann Griffin, Kristin A. Miller, Regina A. Shih, Marcia L. Stefanick, Sverre Vedal, Eric A Whitsel, Joshua Kaufman

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Research Questions

  1. Are individuals with low socio-economic status (SES) more susceptible to the effects of air pollution on cardiovascular disease?
  2. Does SES confound the association between air pollution and cardiovascular disease?

BACKGROUND: Long-term fine particulate matter (PM2.5) exposure is linked with cardiovascular disease, and disadvantaged status may increase susceptibility to air pollution-related health effects. In addition, there are concerns that this association may be partially explained by confounding by socioeconomic status (SES). OBJECTIVES: We examined the roles that individual- and neighborhood-level SES play in the association between PM2.5 exposure and cardiovascular disease. METHODS: The study population comprised 51,754 post-menopausal women from the Women's Health Initiative Observational Study. PM2.5 concentrations were predicted at participant residences using fine-scale regionalized universal kriging models. We assessed individual and neighborhood SES (Census tract-level) across several SES domains including education, occupation, and income/wealth as well as through a neighborhood SES score which captures several important dimensions of SES. Cox proportional-hazards regression adjusted for SES factors and other covariates to determine the risk of a first cardiovascular event. RESULTS: A 5 µg/m3 higher exposure to PM2.5 was associated with a 13% increased risk of cardiovascular event (hazard ratio [HR] 1.13; 95% confidence interval [CI]: 1.02, 1.26). Adjustment for socioeconomic factors did not meaningfully affect the risk estimate. Higher risk estimates were observed in participants living in low SES neighborhoods. The most and least disadvantaged quartiles of the neighborhood SES score had HRs of 1.39 (95% CI: 1.21, 1.61) and 0.90 (95% CI: 0.72, 1.07), respectively. CONCLUSIONS: Women with lower neighborhood SES may be more susceptible to air pollution-related health effects. The association between air pollution and cardiovascular disease was not explained by confounding from individual or neighborhood SES.

Key Findings

  • Women living in disadvantaged neighborhoods may be more susceptible to air pollution-related health effects.
  • Individual and neighborhood SES did not confound the positive association between long-term fine particulate matter and cardiovascular disease.

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