Abstract: TH-PO437

Biased Mortality Risk Associated with Change in Normalized Protein Catabolic Rate Due to Residual Kidney Function among Hemodialysis Patients

Session Information

Category: Nutrition, Inflammation, and Metabolism

  • 1401 Nutrition, Inflammation, Metabolism

Authors

  • Obi, Yoshitsugu, UC Irvine, Orange, California, United States
  • Streja, Elani, UC Irvine, Orange, California, United States
  • Eriguchi, Rieko, Kaizuka Hospital, Fukuoka, Japan
  • Soohoo, Melissa, UC Irvine, Orange, California, United States
  • Rhee, Connie, UC Irvine, Orange, California, United States
  • Kovesdy, Csaba P., University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Kalantar-Zadeh, Kamyar, UC Irvine, Orange, California, United States
Background

Dietary protein intake among hemodialysis (HD) patients is estimated by dialysis urea clearance-based normalized protein catabolic rate (nPCR) in clinical practice, without accounting for renal urea clearance (rCLurea). Decreases in rCLurea directly increase nPCR by imposing greater dialysis clearance, and hence, patients appear to maintain nPCR values with decreased rCLurea and decreased protein intake, both of which are associated with mortality.

Methods

We identified 10,066 HD patients with data on rCLurea at both the 1st and 3rd quarters after dialysis initiation in a large U.S. dialysis organization (2007-2011). We calculated their 6-month change in nPCR with and without accounting for rCLurea (i.e., ΔnPCRtotal and ΔnPCRdial), and created 15 groups of combined ΔnPCRtotal and ΔnPCRdial. All-cause mortality risk was estimated using Cox models with adjustment for 25 clinically relevant factors.

Results

Median (IQR) ΔnPCRdial and ΔnPCRtotal were 0.12 (-0.01, 0.26) and 0.11 (-0.06, 0.28) g/kg/day, respectively. ΔnPCRdial and ΔrCLurea explained 61% and 10% of the variation in ΔnPCRtotal respectively. Within the same category of ΔnPCRdial, adjusted mortality risk was incrementally higher across lower ΔnPCRtotal (Ptrend <0.001). Contrary, within the same category of ΔnPCRtotal, mortality risk was paradoxically higher across higher ΔnPCRdial (Ptrend <0.001).

Conclusion

In the absence of data on rCLurea, ΔnPCR does not adequately capture true changes in protein intake, leading to a biased evaluation of associated mortality risk among HD patients with rCLurea.

Funding

  • NIDDK Support