County-level air quality and the prevalence of diagnosed chronic kidney disease in the US Medicare population

PLoS One. 2018 Jul 31;13(7):e0200612. doi: 10.1371/journal.pone.0200612. eCollection 2018.

Abstract

Background: Considerable geographic variation exists in the prevalence of chronic kidney disease across the United States. While some of this variability can be explained by differences in patient-level risk factors, substantial variability still exists. We hypothesize this may be due to understudied environmental exposures such as air pollution.

Methods: Using data on 1.1 million persons from the 2010 5% Medicare sample and Environmental Protection Agency air-quality measures, we examined the association between county-level particulate matter ≤2.5 μm (PM2.5) and the prevalence of diagnosed CKD, based on claims. Modified Poisson regression was used to estimate associations (prevalence ratios [PR]) between county PM2.5 concentration and individual-level diagnosis of CKD, adjusting for age, sex, race/ethnicity, hypertension, diabetes, and urban/rural status.

Results: Prevalence of diagnosed CKD ranged from 0% to 60% by county (median = 16%). As a continuous variable, PM2.5 concentration shows adjusted PR of diagnosed CKD = 1.03 (95% CI: 1.02-1.05; p<0.001) for an increase of 4 μg/m3 in PM2.5. Investigation by quartiles shows an elevated prevalence of diagnosed CKD for mean PM2.5 levels ≥14 μg/m3 (highest quartile: PR = 1.05, 95% CI: 1.03-1.07), which is consistent with current ambient air quality standard of 12 μg/m3, but much lower than the level typically considered healthy for sensitive groups (~40 μg/m3).

Conclusion: A positive association was observed between county-level PM2.5 concentration and diagnosed CKD. The reliance on CKD diagnostic codes likely identified associations with the most severe CKD cases. These results can be strengthened by exploring laboratory-based diagnosis of CKD, individual measures of exposure to multiple pollutants, and more control of confounding.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Air Pollutants / toxicity*
  • Air Pollution / statistics & numerical data*
  • Cross-Sectional Studies
  • Environmental Exposure / adverse effects*
  • Female
  • Humans
  • Male
  • Medicare / statistics & numerical data
  • Particulate Matter / toxicity*
  • Prevalence
  • Renal Insufficiency, Chronic / epidemiology*
  • Renal Insufficiency, Chronic / etiology
  • Risk Assessment
  • United States
  • United States Environmental Protection Agency / statistics & numerical data

Substances

  • Air Pollutants
  • Particulate Matter

Grant support

This research was supported by the Supporting, Maintaining and Improving the Surveillance System for Chronic Kidney Disease in the U.S., Cooperative Agreement Number, U58 DP006254, funded by the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention or the Department of Health and Human Services. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.