Ambient Air Pollution and Mortality among Older Patients Initiating Maintenance Dialysis

Abstract

<b><i>Background:</i></b> Fine particulate matter (particulate matter with diameter <2.5 µm [PM<sub>2.5</sub>]) 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<sub>2.5</sub>, it is unclear whether older patients on dialysis are at elevated risk of mortality when exposed to fine particulate matter. <b><i>Methods:</i></b> Older adults initiating dialysis (2010–2016) were identified from US Renal Data System (USRDS). PM<sub>2.5</sub> concentrations were obtained from NASA’s Socioeconomic Data and Application Center (SEDAC) Global Annual PM<sub>2.5</sub> Grids. We investigated the association between PM<sub>2.5</sub> 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<sub>2.5</sub> of 12 μg/m<sup>3</sup>] and robust variance. <b><i>Results:</i></b> For older dialysis patients who resided in areas with high PM<sub>2.5</sub>, a 10 μg/m<sup>3</sup> increase in PM<sub>2.5</sub> 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<sub>2.5</sub>. While the mortality risk associated with PM<sub>2.5</sub> was stronger at higher levels (aHR = 1.19, 95% CI: 1.08–1.32), at lower levels (≤12 μg/m<sup>3</sup>), PM<sub>2.5</sub> was significantly associated with mortality risk (aHR = 1.04, 95% CI: 1.00–1.07) among patients aged ≥75 years (P<sub>slope difference</sub> = 0.006). <b><i>Conclusions:</i></b> Older adults initiating dialysis who resided in ZIP codes with PM<sub>2.5</sub> levels >12 μg/m<sup>3</sup> are at increased risk of mortality. Those aged >75 were at elevated risk even at levels below the EPA Standard for PM<sub>2.5</sub>.

Breathing Air into Clinical Care

“…We welcome the attention that Feng et al's [1] research draws to the associations between poor air quality and kidney disease. With this attention, we now emphasize an underappreciated corollary of their findings, namely, that in order to appropriately treat their patients, clinicians must advocate for individual-and populationlevel interventions that reduce their patients' exposure to poor air quality.…”

“…We make this recommendation through the lens of health justice, as communities that are disproportionately impacted by kidney disease are also those that are exposed to higher levels of air pollution [7,8]. Indeed, the findings of Feng et al [1] demonstrate these disparities, as older Black patients in their study had a higher PM 2.5 -associated mortality risk than non-Hispanic whites. While these systematically disadvantaged communities are bearing the burden of policy choices that expose them to poor air quality, it is imperative for those who treat them to advocate for the policy changes that could rectify this disparity.…”

“…In their current article entitled "Ambient Air Pollution and Mortality among Older Patients Initiating Maintenance Dialysis," Feng and colleagues [1] have added to an emerging tapestry of data that links fine particulate matter air pollution (PM 2.5 ) to adverse kidney outcomes. Using patient information from the United States Renal Data System (USRDS), the authors analyzed data from almost 400,000 individuals aged 65 years or older initiating dialysis, and found higher death rates if the patient resided in zip codes where average annual PM 2.5 levels exceeded 12 µg/m 3 , while the risk began at lower levels among those older than 75 years.…”

“…We write this editorial in recognition of a near-universal neglect of environmental exposures as critical, and crucially, modifiable determinants of kidney health. Studies such as Feng and colleagues' [1] provide abundant reason for those who treat patients across the spectrum of kidney disease to be concerned about the deleterious impact of air pollution. We must do better.…”

“…We recognize that the ecological nature of air quality undoubtedly creates challenges for how to best incorporate exposure mitigation into the practice of medicine; however, Feng et al [1] suggest that failing to address those risk factors can be a matter of life or death. The question only becomes how do we move from our knowledge of the importance of good air quality to actionable DOI: 10.1159/000514235 changes to clinical practice that will support patient wellness.…”