Ambient Air Pollution and Mortality among Older Patients Initiating Maintenance Dialysis

Background: Fine particulate matter (particulate matter with diameter <2.5 µm [PM 2.5 ]) is associated with CKD progression and may impact the health of patients living with kidney failure. While older (aged ≥65 years) adults are most vulnerable to the impact of PM 2.5 , it is unclear whether older patients on dialysis are at elevated risk of mortality when exposed to fine particulate matter. Methods: Older adults initiating dialysis (2010–2016) were identified from US Renal Data System (USRDS). PM 2.5 concentrations were obtained from NASA’s Socioeconomic Data and Application Center (SEDAC) Global Annual PM 2.5 Grids. We investigated the association between PM 2.5 and all-cause mortality using Cox proportional hazard models with linear splines [knot at the current Environmental Protection Agency (EPA) National Ambient Air Quality Standard for PM 2.5 of 12 μg/m 3 ] and robust variance. Results: For older dialysis patients who resided in areas with high PM 2.5 , a 10 μg/m 3 increase in PM 2.5 was associated with 1.16-fold (95% CI: 1.08–1.25) increased risk of mortality; furthermore, those who were female (aHR = 1.26, 95% CI: 1.13–1.42), Black (aHR = 1.31, 95% CI: 1.09–1.59), or had diabetes as a primary cause of kidney failure (aHR = 1.25, 95% CI: 1.13–1.38) were most vulnerable to high PM 2.5 . While the mortality risk associated with PM 2.5 was stronger at higher levels (aHR = 1.19, 95% CI: 1.08–1.32), at lower levels (≤12 μg/m 3 ), PM 2.5 was significantly associated with mortality risk (aHR = 1.04, 95% CI: 1.00–1.07) among patients aged ≥75 years (P slope difference = 0.006). Conclusions: Older adults initiating dialysis who resided in ZIP codes with PM 2.5 levels >12 μg/m 3 are at increased risk of mortality. Those aged >75 were at elevated risk even at levels below the EPA Standard for PM 2.5 .