Neighborhood Factors, Air Pollution, and Mortality Among Kidney Failure Patients: Exploring Differences by Race and Ethnicity

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Rationale & Objective Fine particulate matter (PM 2.5 ) is associated with increased mortality and disproportionately affects minoritized patients with kidney failure, particularly Black patients. Among patients with kidney failure, we tested whether neighborhood characteristics (racial and ethnic segregation, socioeconomic deprivation, and built environment) modified the association between PM 2.5 exposure and mortality, overall and by race and ethnicity. Study Design Cohort study (2003-2019). Setting & Participants National registry for patients with kidney failure. Exposures Annualized PM 2.5 concentrations (high, > 9 μg/m 3 ), segregation scores (Theil's H method), deprivation scores (American Community Survey), and built environment factors (medically underserved areas [MUA] and urbanicity) by patients' residential ZIP code at dialysis initiation. Outcome All-cause mortality. Analytical Approach We used multivariable Cox regression with shared state-level frailty to quantify whether neighborhood factors modify the association between PM 2.5 and mortality, overall and stratified by race and ethnicity. Results High PM 2.5 (vs low) was differentially associated with mortality among patients with kidney failure residing in neighborhoods characterized by high segregation (adjusted hazard ratio [aHR], 1.17; 95% confidence interval [CI], 1.15-1.19; P interaction high vs low < 0.001), high deprivation (aHR, 1.17; 95% CI, 1.15-1.19; P interaction high vs low < 0.001), MUA (aHR, 1.15; 95% CI, 1.13-1.16; P interaction = 0.005), and high-density urban (HDU) areas (aHR, 1.14; 95% CI, 1.12-1.15; P interaction < 0.001). These differential associations were most prominent among Black patients ([high segregation: aHR, 1.25; 95% CI, 1.21-1.29; P interaction high vs low = 0.006], [high deprivation: aHR, 1.26; 95% CI, 1.22-1.30; P interaction high vs low < 0.001], [MUA: aHR, 1.22; 95% CI, 1.19-1.26; P interaction = 0.02], [HDU areas: aHR, 1.23; 95% CI, 1.20-1.26; P interaction < 0.001]) Limitations Outdoor PM 2.5 may not reflect individual-level exposures. Conclusions High levels of PM 2.5 were associated with increased mortality risk among patients with kidney failure residing in neighborhoods characterized by high segregation, high deprivation, MUAs, and HDU areas, particularly among Black patients. Nephrologists should consider closer monitoring of patients, particularly those from minoritized groups who reside in these high-risk neighborhoods, to help mitigate the adverse effects of PM 2.5 and reduce related mortality. Plain-language Summary Exposure to high levels of fine particulate matter (PM 2.5 ), a form of air pollution, disproportionately affects minoritized patients with kidney failure, particularly Black patients. Residential neighborhood characteristics may explain both the overall association between PM 2.5 exposure and mortality and the racial and ethnic differences in this association among patients with kidney failure in the United States. In this study, we found that high PM 2.5 levels were associated with increased mortality risk in neighborhoods characterized by high segregation and high deprivation, medically underserved areas, and HDU areas. These associations were most prominent among Black patients with kidney failure. Our findings underscore the need for clinicians to identify and monitor high-risk populations to reduce mortality risk related to PM 2.5 , particularly among Black patients.