Division of Nephrology, University HospItal A Coruña, La Coruña, Spain.
Nephrol Dial Transplant. 2019 Aug 1;34(8):1394-1400. doi: 10.1093/ndt/gfy393.
Preservation of residual kidney function (RKF) is a relevant objective in peritoneal dialysis (PD) patients. The influence of dietary protein intake (PI) on this variable has not been adequately investigated.
Following an observational design, we studied 336 patients incident on PD, with a minimum follow-up of 6 months. The main study variable was the mean PI [normalized rate of protein nitrogen appearance (nPNA)] during the first 4 months on PD. The main outcome variables were the absolute rate of decline of RKF and the proportion of patients presenting a >50% decay of their RKF during the first year of follow-up. We applied univariate and multivariate strategies of analysis, taking into consideration the main control variables bearing a correlation with nPNA and/or RKF.
Mean nPNA (first 4 months) was 1.23 ± 0.33 g/kg/day, while the overall rate of decline of RKF was -0.13 ± 0.29 mL/min/month; 69 patients (25.1%) had lost >50% of their initial RKF by the end of the first year. Univariate analysis disclosed consistent associations between the main study variable on one hand and baseline RKF (r = 0.32, P < 0.0005) and its rate of decline (r = -0.23, P < 0.0005) on the other. The latter two variables were also significantly correlated (r = -0.36, P < 0.0005). Multivariate analysis identified mean nPNA as an independent predictor of the rate of decline of RKF [odds ratio 1.09 per 0.10 g/kg/day, 95% confidence interval (CI) 0.99-1.19, P = 0.058] and, in particular, of the probability of losing >50% of the baseline RKF during the first year of treatment (odds ratio 1.15 per 0.10 g/kg/day, 95% CI 1.04-1.27, P = 0.006).
Higher rates of PI during the first months of therapy are associated with a faster decline of RKF among patients incident on PD. Our results underline the convenience of keeping an adequate balance between sufficient protein ingestion, to prevent malnutrition and wasting, and sensible restriction in stable, adequately nourished individuals with rates of intake in the higher range or above-recommended allowances.
保留残余肾功能（RKF）是腹膜透析（PD）患者的一个相关目标。饮食蛋白摄入量（PI）对这一变量的影响尚未得到充分研究。
采用观察性设计，我们研究了 336 例新开始 PD 的患者，随访时间至少为 6 个月。主要研究变量是 PD 开始后前 4 个月的平均 PI[标准化蛋白氮表观率（nPNA）]。主要结局变量是 RKF 绝对下降率和随访第 1 年期间 RKF 下降>50%的患者比例。我们应用了单变量和多变量分析策略，考虑了与 nPNA 和/或 RKF 相关的主要控制变量。
平均 nPNA（前 4 个月）为 1.23±0.33g/kg/天，而 RKF 的总体下降率为-0.13±0.29mL/min/月；随访第 1 年末，69 例患者（25.1%）丧失了初始 RKF 的>50%。单变量分析显示，主要研究变量与基线 RKF（r=0.32，P<0.0005）及其下降率（r=-0.23，P<0.0005）之间存在一致的相关性。后两个变量也呈显著相关性（r=-0.36，P<0.0005）。多变量分析将平均 nPNA 确定为 RKF 下降率的独立预测因子[每增加 0.10g/kg/天的 nPNA，比值比为 1.09，95%置信区间（CI）为 0.99-1.19，P=0.058]，特别是在治疗的第 1 年期间丧失>50%基线 RKF 的可能性（每增加 0.10g/kg/天的 nPNA，比值比为 1.15，95%CI 为 1.04-1.27，P=0.006）。
在 PD 开始的头几个月内摄入较高的 PI 与 RKF 的快速下降有关。我们的结果强调了在摄入充足的蛋白质以预防营养不良和消耗的同时，保持足够的平衡，以及在摄入量处于较高范围或超过推荐量的稳定、营养充足的个体中进行合理限制的便利性。
