Research Article: Air Pollution and the Microvasculature: A Cross-Sectional Assessment of In Vivo Retinal Images in the Population-Based Multi-Ethnic Study of Atherosclerosis (MESA)

Date Published: November 30, 2010

Publisher: Public Library of Science

Author(s): Sara D. Adar, Ronald Klein, Barbara E. K. Klein, Adam A. Szpiro, Mary Frances Cotch, Tien Y. Wong, Marie S. O’Neill, Sandi Shrager, R. Graham Barr, David S. Siscovick, Martha L. Daviglus, Paul D. Sampson, Joel D. Kaufman, Bruce P. Lanphear

Abstract: Sara Adar and colleagues show that residing in locations with higher air pollution concentrations and experiencing daily increases in air pollution are associated with narrower retinal arteriolar diameters in older individuals, thus providing a link between air pollution and cardiovascular disease.

Partial Text: Long- and short-term exposures to ambient and traffic-related air pollution, especially fine particulate matter (particulate matter less than 2.5 µm in aerodynamic diameter, or PM2.5), have been linked to higher rates of cardiovascular morbidity and mortality [1]–[5]. It has been hypothesized that impacts on microvascular function may play a role in these associations [6]. Toxicological studies support this hypothesis as they have demonstrated that PM2.5 can impair microvascular endothelium-dependent dilation [7]. One human study also demonstrated air pollution and exercise-induced ischemia in a pattern that was more consistent with impaired myocardial microvascular flow than altered larger epicardial vessel coronary circulation [8]. Other human studies have shown links between air pollution and impaired vasodilatation or enhanced vasoconstriction in the forearm [9]–[12], but none have directly explored associations with the microvasculature.

With retinal data missing for 283 participants, address or exposure data missing for 1,104 persons, and covariate data missing for 243 persons, 4,607 individuals were examined in this analysis. Descriptive statistics are presented in Table 1 for individuals with complete information as well as those individuals excluded from analysis. Included participants were 53% women among four race/ethnicities (40% white, 26% African American, 12% Chinese American, and 22% Hispanic). Of the Hispanics in the population, 52%, 14%, 14%, and 35% were of Mexican, Dominican, Puerto Rican, and other descent, respectively. With a mean age of 63 y, 44% of the population had hypertension, 13% had diabetes (an additional 15% had impaired glucose), and 58% had a family history of cardiovascular disease. Excluded individuals were qualitatively similar to the main cohort although they were slightly older, of lower socioeconomic position, and had higher prevalence of hypertension and diabetes.

In a large population-based cohort study of adults without preexisting cardiovascular disease, we found independent associations between long- and short-term concentrations of fine particulate air pollution and vessel diameters of the retinal microvasculature, as measured using standardized photographic methods. Increased air pollution concentrations were associated with retinal arteriolar narrowing, an outcome that has previously been associated with increased risk of myocardial infarction, stroke, hypertension, and cardiovascular mortality, independent of other traditional risk factors. [13]–[19].



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