Daily protein intake and survival in patients on peritoneal dialysis

BACKGROUND: The decreased protein intake may lead to protein-energy wasting and poor survival. It is unknown what the appropriate protein intake in patients on peritoneal dialysis (PD) is. We aimed to explore the appropriate levels of daily protein intake (DPI) in favor of outcome in a large PD cohort. METHODS: Our study enrolled 305 incident patients, who could be followed regularly. Demographic data were collected at baseline. Biochemical, dietary and nutritional data and dialysis adequacy were measured at the baseline and thereafter at regular intervals. Outcome events included all-cause death, cardiovascular disease (CVD) death and first-episode peritonitis. RESULTS: A total of 127 patients died during the 44.5-month follow-up, 41.7% of whom died from CVD. A total of 129 cases first-episode peritonitis were observed. Patients with a high tertile of baseline DPI (≥ 0.94 g/kg/day) had significantly higher serum albumin, prealbumin, hemoglobin, lean body mass and handgrip strength compared to the low tertile group (≤ 0.73 g/kg/day) (P < 0.05-0.001). They also had significantly lower risk for all-cause, CVD death and first-episode peritonitis than the low tertile group adjusted for commonly recognized confounders. Although patients in the middle tertile of DPI (0.74-0.93 g/kg/day) did not show significant differences in the majority of nutritional markers, all-cause and CVD mortality compared to high tertile group, they had a trend to a negative nitrogen balance and similar risk for first-episode peritonitis to the low tertile group. The DPI included as a time-dependent variable could not predict any outcome events in multivariate Cox models. CONCLUSIONS: Our study revealed that DPI <0.73 g/kg/day was associated with protein-energy wasting and worst outcome for PD patients. The DPI >0.94 g/kg/day was in favor of nutrition status and long-term outcome in this population.