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Abstract: PO1081

Physiological Pre-Dialytic Changes Could Mediate the Effects of Extreme Heat Events on Hospital Admission Risk in Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Remigio, Richard V., University of Maryland School of Public Health, College Park, Maryland, United States
  • Turpin, Rodman Emory, University of Maryland School of Public Health, College Park, Maryland, United States
  • Raimann, Jochen G., Renal Research Institute, New York, New York, United States
  • Kotanko, Peter, Renal Research Institute, New York, New York, United States
  • Maddux, Franklin W., Fresenius Medical Care AG und Co KGaA, Bad Homburg, Hessen, Germany
  • Usvyat, Len A., Fresenius Medical Care North America, Waltham, Massachusetts, United States
  • He, Xin, University of Maryland School of Public Health, College Park, Maryland, United States
  • Sapkota, Amir, University of Maryland School of Public Health, College Park, Maryland, United States
Background

Thermoregulatory response to extreme heat events (EHE) includes reduced blood pressure and perspiration. EHE exposure increases the risk of hospitalizations among hemodialysis (HD) patients, though the underlying mechanism for this relationship is unclear. We employed traditional mediation analysis to decompose the total effect between EHE and hospital admissions using pre-HD systolic blood pressure (SBP) and interdialytic weight gain (IDWG) as mediators.

Methods

We assigned EHE exposure metric – calculated using calendar day and location-specific temperature thresholds – to HD patients treated at Fresenius Kidney Care clinics from 2003 to 2012. We used time-to-event methods using varying lag periods followed by VanderWeele’s difference method with bootstrapping to test mediators.

Results

EHE increased the hazard of hospital admission up to 17% after covariate adjustments (n=7,962). In one of the lag periods (two-day EHE exposure before hospital admissions), hazard ratio (HR) estimates from Cox models (Figure) exhibited statistical significance for all pathways. SBP and IDWG as a conjoined mediator suggest protective mediation (-48.3%), whereas IDWG, independent of SBP, accounts for a considerable proportion of the association (88.7%). Half of the association is mediated through SBP, independent of IDWG. Preliminarily, IDWG may have a consistent mechanistic role in hospital admissions after exposure. Also, lagged EHE does yield heterogeneity in mediating effects.

Conclusion

This work is a step forward to understanding potential physiological linkages between EHEs and health complications that may result in hospitalization. Such findings could be critical in discerning potential interventions to minimize the impact of extreme heat among HD patients.

L: HR and 95% CI for EHE-Hospital association (EHE HR) and for mediation effects of the association (Indirect Effects); R: Mediating EHE-Hospital association pathways and its relative proportions

Funding

  • Other U.S. Government Support