Relationship of Normalized Protein Catabolic Rate with Nutrition Status and Long-Term Survival in Peritoneal Dialysis Patients

The normalized protein catabolic rate (nPCR) reflects daily dietary protein intake in stable dialysis patients. In peritoneal dialysis (PD) patients, reports about the importance of nPCR as marker of nutrition and outcome have been inconsistent. The objective of the present study was to investigate the relationships of nPCR with body composition parameters, micronutrient electrolytes, and long-term survival in PD patients. From November 2000 to May 2008, 57 PD patients were enrolled in the study. On enrollment, demographic, clinical, and biochemical data were recorded. Patients were followed through September 2011. Mean age of the patients was 56 years, and 61% were of African descent. Mean and maximum follow-up were 2.83 years and 11 years respectively. Mean daily nPCR was 0.944 g/kg. The nPCR correlated directly with albumin (r = 0.34, p = 0.012), magnesium (r = 0.48, p < 0.0001), phosphorus (r = 0.42, p = 0.02), and the phase angle body composition parameter (r = 0.26, p = 0.049). Compared with patients whose enrollment daily nPCR was less than 0.8 g/kg, those with an enrollment daily nPCR of 0.8 g/kg or more experienced significantly better 11-year cumulative survival (p = 0.04). In multivariate Cox regression analysis with adjustment for confounding variables, nPCR was an independent predictor of all-cause mortality (p = 0.018). In conclusion, lower nPCR is associated with poorer nutrition status and increased risk of all-cause mortality in PD patients followed for up to 11 years.