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Abstract: SA-PO1059

Exposure to Wildfire Smoke Increases Mortality in US Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Xi, Yuzhi, Oak Ridge Institute for Science and Education, United States Environmental Protection Agency, NHEERL, Chapel Hill, North Carolina, United States
  • Kshirsagar, Abhijit V., University of North Carolina, Chapel Hill, North Carolina, United States
  • Wade, Timothy J., United States Environmental Protection Agency, Research Triangle Park, North Carolina, United States
  • Richardson, David, University of North Carolina, Chapel Hill, North Carolina, United States
  • Brookhart, M. Alan, University of North Carolina, Chapel Hill, North Carolina, United States
  • Rappold, Ana G., United States Environmental Protection Agency, Research Triangle Park, North Carolina, United States
Background

Wildfires are a significant source of fine particulate matter (PM2.5) that is causally related to mortality. Our objective is to assess the effect of wildfire-PM2.5 on daily mortality among patients receiving chronic in-center hemodialysis (HD) in the US.

Methods

From the United States Renal Data System (USRDS), we identified patients who 1) had Medicare as primary payer, 2) survived first 3 months of dialysis, and 3) visited dialysis clinics within the 627 counties impacted by at least one large wildfire between 2008-2012. Outcomes were daily all-cause mortality and all-cause mortality by place of death (clinical and nonclinical). Exposure was county-level daily wildfire-PM2.5 concentrations. We tested the association of wildfire-PM2.5 exposure to daily mortality using time series analysis, while controlling for time-dependent factors (temperature, etc.) and by design for time-independent characteristics (demographics and comorbidities). The immediate (same day) effect and the cumulative effect of 1, 7, 14, and 30 days of the exposure to wildfire-PM2.5 on mortality were expressed as adjusted rate ratios (RR) per 10 mg/m3increase in PM2.5.

Results

Among 48,454 deaths, the RR of the same day effect on all-cause mortality was 1.04 (95%CI: 1.01-1.07) and the cumulative effects of 1, 7, 14, and 30 days following the exposure were 1.05 (1.02-1.08), 1.07 (1.03-1.11), 1.06 (1.01-1.10), and 1.07 (1.01-1.12), respectively. For all-cause death occurring in non-clinical settings, the RR of the same day effect was 1.07 (95%CI: 1.02, 1.12), and the respective RRs of cumulative effect were 1.07 (95%CI: 1.02, 1.12), 1.09 (95%CI: 1.02, 1.15), 1.07 (95%CI: 1.00, 1.15), and 1.09 (95%CI: 1.01, 1.18).

Conclusion

Wildfire-PM2.5 exposure was associated with a ~5% increase in daily all-cause mortality rate among HD patients. These deaths occurred in non-clinical settings such as homes, where exposure to PM2.5 may be exacerbated. The first of its kind study highlights the impact of environmental exposures on a fragile population, and the need for additional research. This abstract does not reflect EPA policy.

Funding

  • Other U.S. Government Support