Kidney Week

Abstract: TH-PO319

Associations of Blood Water Cleared during a Dialysis Session Scaled to Body Surface Area with Weight-Specific Mortality Risk

Session Information

• Hemodialysis and Frequent Dialysis - 1
  October 24, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 801 Dialysis: Hemodialysis and Frequent Dialysis

Authors

• Daugirdas, John T., University of Illinois Chicago College of Medicine, Chicago, Illinois, United States

John T. Daugirdas, MD, FASN

• Mermelstein, Ariella E., Renal Research Institute, New York, New York, United States

Ariella E. Mermelstein, MA

• Wang, Yuedong, University of California Santa Barbara, Santa Barbara, California, United States

Yuedong Wang, PhD

• Raimann, Jochen G., Renal Research Institute, New York, New York, United States

Jochen G. Raimann, MD, PhD, MPH

• Kotanko, Peter, Renal Research Institute, New York, New York, United States

Peter Kotanko, MD, FASN

Background

Lowrie et al (Kidney Int, 2005) suggested using volume of blood water cleared during a dialysis session (K x t) normalized to body surface area (S) for a size-dependent adequacy target.

Methods

We examined associations between estimated K (Kdest, vivo/vitro KoA ratio of 0.43) or measured K (conductivity, Kecn) scaled to S (Dubois equation) and survival for different strata of post-dialysis weights (W). Mean dialysis dose data were analyzed from the US Fresenius Kidney Care database for 1 year after dialysis initiation (baseline) and deaths were counted over the next 2 years. To investigate the joint effect of Kt/V or Kt/S and W on survival, we fit Cox proportional hazards models using bivariate tensor product spline functions and constructed contour plots of W-specific mortality hazard ratios over the entire range of dialysis dose values and W.

Results

In 233,293 patients, mean Kecn x t was 57 ± 7.4 liters/session in men, 53 ± 7.1 in women. Mean Kdest was 57 ± 6.2 liters/session in men, 53 ± 6.3 in women. Contour plots suggested a Kt/S target which decreased risk had somewhat plateaued of 37 – 10/W liters/m² for either sex, for both Kecn and Kdest, but mortality risk increased more steeply in men when dose fell below this value. For unknown reasons, mortality risk was higher in heavier patients (>80 kg), especially women, when Kt/S was greater than 32 liters/m².

Conclusion

Our findings agreed with Lowrie et al, that a Kt/S adequacy target would need to be scaled to patient size (either as S or W). Increased mortality in patients given very high doses of dialysis was a surprising finding and deserves further study.