Particulate Matter Air Pollution and the Risk of Incident CKD and Progression to ESRD

Elevated levels of fine particulate matter <2.5 µ m in aerodynamic diameter (PM 2.5 ) are associated with increased risk of cardiovascular outcomes and death, but their association with risk of CKD and ESRD is unknown. We linked the Environmental Protection Agency and the Department of Veterans Affairs databases to build an observational cohort of 2,482,737 United States veterans, and used survival models to evaluate the association of PM 2.5 concentrations and risk of incident eGFR <60 ml/min per 1.73 m 2 , incident CKD, eGFR decline ≥30%, and ESRD over a median follow-up of 8.52 years. County-level exposure was defined at baseline as the annual average PM 2.5 concentrations in 2004, and separately as time-varying where it was updated annually and as cohort participants moved. In analyses of baseline exposure (median, 11.8 [interquartile range, 10.1–13.7] µ g/m 3 ), a 10- µ g/m 3 increase in PM 2.5 concentration was associated with increased risk of eGFR<60 ml/min per 1.73 m 2 (hazard ratio [HR], 1.21; 95% confidence interval [95% CI], 1.14 to 1.29), CKD (HR, 1.27; 95% CI, 1.17 to 1.38), eGFR decline ≥30% (HR, 1.28; 95% CI, 1.18 to 1.39), and ESRD (HR, 1.26; 95% CI, 1.17 to 1.35). In time-varying analyses, a 10- µ g/m 3 increase in PM 2.5 concentration was associated with similarly increased risk of eGFR<60 ml/min per 1.73 m 2 , CKD, eGFR decline ≥30%, and ESRD. Spline analyses showed a linear relationship between PM 2.5 concentrations and risk of kidney outcomes. Exposure estimates derived from National Aeronautics and Space Administration satellite data yielded consistent results. Our findings demonstrate a significant association between exposure to PM 2.5 and risk of incident CKD, eGFR decline, and ESRD.