Ambient Air Pollution and Mortality among Older Patients Initiating Maintenance Dialysis

Abstract

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/m³] and robust variance. Results: For older dialysis patients who resided in areas with high PM_2.5, a 10 μg/m³ 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/m³), 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/m³ are at increased risk of mortality. Those aged >75 were at elevated risk even at levels below the EPA Standard for PM_2.5.