Kidney Week

Abstract: TH-PO437

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

Session Information

• Nutrition, Inflammation, Metabolism: Basic Mechanisms
  November 02, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Nutrition, Inflammation, and Metabolism

• 1401 Nutrition, Inflammation, Metabolism

Authors

• Obi, Yoshitsugu, UC Irvine, Orange, California, United States

Yoshitsugu Obi,

• Streja, Elani, UC Irvine, Orange, California, United States

Elani Streja,

• Eriguchi, Rieko, Kaizuka Hospital, Fukuoka, Japan

Rieko Eriguchi,

• Soohoo, Melissa, UC Irvine, Orange, California, United States

Melissa Soohoo,

• Rhee, Connie, UC Irvine, Orange, California, United States

Connie Rhee,

• Kovesdy, Csaba P., University of Tennessee Health Science Center, Memphis, Tennessee, United States

Csaba P. Kovesdy,

• Kalantar-Zadeh, Kamyar, UC Irvine, Orange, California, United States

Kamyar Kalantar-Zadeh,

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 (rCL_urea). Decreases in rCL_urea directly increase nPCR by imposing greater dialysis clearance, and hence, patients appear to maintain nPCR values with decreased rCL_urea and decreased protein intake, both of which are associated with mortality.

Methods

We identified 10,066 HD patients with data on rCL_urea 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 rCL_urea (i.e., ΔnPCR_total and ΔnPCR_dial), and created 15 groups of combined ΔnPCR_total and ΔnPCR_dial. All-cause mortality risk was estimated using Cox models with adjustment for 25 clinically relevant factors.

Results

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

Conclusion

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

Funding

• NIDDK Support