Eriguchi Rieko, Obi Yoshitsugu, Streja Elani, Tortorici Amanda R, Rhee Connie M, Soohoo Melissa, Kim Taehee, Kovesdy Csaba P, Kalantar-Zadeh Kamyar
Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California, Irvine, Orange, California.
Nephrology Section, Tibor Rubin Veterans Affairs Medical Center, Long Beach, California.
Clin J Am Soc Nephrol. 2017 Jul 7;12(7):1109-1117. doi: 10.2215/CJN.13141216. Epub 2017 May 10.
There are inconsistent reports on the association of dietary protein intake with serum albumin and outcomes among patients on hemodialysis. Using a new normalized protein catabolic rate (nPCR) variable accounting for residual renal urea clearance, we hypothesized that higher baseline nPCR and rise in nPCR would be associated with higher serum albumin and better survival among incident hemodialysis patients.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Among 36,757 incident hemodialysis patients in a large United States dialysis organization, we examined baseline and change in renal urea clearance-corrected nPCR as a protein intake surrogate and modeled their associations with serum albumin and mortality over 5 years (1/2007-12/2011).
Median nPCRs with and without accounting for renal urea clearance at baseline were 0.94 and 0.78 g/kg per day, respectively (median within-patient difference, 0.14 [interquartile range, 0.07-0.23] g/kg per day). During a median follow-up period of 1.4 years, 8481 deaths were observed. Baseline renal urea clearance-corrected nPCR was associated with higher serum albumin and lower mortality in the fully adjusted model (<0.001). Among 13,895 patients with available data, greater rise in renal urea clearance-corrected nPCR during the first 6 months was also associated with attaining high serum albumin (≥3.8 g/dl) and lower mortality (<0.001); compared with the reference group (a change of 0.1-0.2 g/kg per day), odds and hazard ratios were 0.53 (95% confidence interval, 0.44 to 0.63) and 1.32 (95% confidence interval, 1.14 to 1.54), respectively, among patients with a change of <-0.2 g/kg per day and 1.62 (95% confidence interval, 1.35 to 1.96) and 0.76 (95% confidence interval, 0.64 to 0.90), respectively, among those with a change of ≥0.5 g/kg per day. Within a given category of nPCR without accounting for renal urea clearance, higher levels of renal urea clearance-corrected nPCR consistently showed lower mortality risk.
Among incident hemodialysis patients, higher dietary protein intake represented by nPCR and its changes over time appear to be associated with increased serum albumin levels and greater survival. nPCR may be underestimated when not accounting for renal urea clearance. Compared with the conventional nPCR, renal urea clearance-corrected nPCR may be a better marker of mortality.
关于血液透析患者饮食蛋白质摄入量与血清白蛋白及预后之间的关联，报告结果并不一致。我们使用一种新的考虑残余肾尿素清除率的标准化蛋白分解代谢率（nPCR）变量，推测较高的基线nPCR及nPCR的升高与新进入血液透析的患者血清白蛋白水平较高及生存率较好相关。
设计、地点、参与者与测量指标：在美国一家大型透析机构的36757例新进入血液透析的患者中，我们将经肾尿素清除率校正的nPCR的基线水平及变化作为蛋白质摄入量的替代指标，并建立模型分析其与血清白蛋白及5年（2007年1月至2011年12月）死亡率之间的关联。
基线时考虑肾尿素清除率和未考虑肾尿素清除率的nPCR中位数分别为0.94和0.78g/（kg·天）（患者内中位数差异为0.14[四分位间距为0.07 - 0.23]g/（kg·天））。在中位随访期1.4年期间，观察到8481例死亡。在完全校正模型中，基线经肾尿素清除率校正的nPCR与较高的血清白蛋白水平及较低的死亡率相关（P<0.001）。在13895例有可用数据的患者中，最初6个月内经肾尿素清除率校正的nPCR升高幅度较大也与达到较高血清白蛋白水平（≥3.8g/dl）及较低死亡率相关（P<0.001）；与参照组（变化幅度为0.1 - 0.2g/（kg·天））相比，变化幅度<-0.2g/（kg·天）的患者的比值比和风险比分别为0.53（95%置信区间为0.44至0.63）和1.32（95%置信区间为1.14至1.54），变化幅度≥0.5g/（kg·天）的患者的比值比和风险比分别为1.62（95%置信区间为1.35至1.96）和0.76（95%置信区间为0.64至0.90）。在不考虑肾尿素清除率的给定nPCR类别中，经肾尿素清除率校正的nPCR水平较高始终显示较低的死亡风险。
在新进入血液透析的患者中，以nPCR表示的较高饮食蛋白质摄入量及其随时间的变化似乎与血清白蛋白水平升高及生存率提高相关。不考虑肾尿素清除率时，nPCR可能被低估。与传统nPCR相比，经肾尿素清除率校正的nPCR可能是更好的死亡率标志物。
