Protein-Energy Wasting and Mortality Risk Prediction Among Peritoneal Dialysis Patients

Abstract

Protein-energy wasting (PEW) is defined as the loss of body protein and energy reserves associated with kidney disease. However, the extent to which PEW contributes to increased mortality among peritoneal dialysis (PD) patients remains unclear. This is a retrospective cohort study from 2012 to 2020. The PEW was diagnosed by applying at least 3 of the 4 following criteria: (1) altered serum biochemistry indicated by a serum albumin level of <3.5g/L; (2) decreased body mass status identified by a body mass index (BMI) of <23kg/m2 or <10% total body fat; (3) muscle wasting defined by the lean tissue index, calculated as a lean tissue mass normalized to the height-squared in the <10th percentile of the reference population; and (4) low dietary protein intake determined by the normalized protein equivalent of a total nitrogen appearance of <0.8g/kg/day. The Malnutrition Inflammation Score (MIS) was also examined as an alternative tool for assessment of PEW. The average age of the 555 participants was 57.5±12.6years. The prevalence of PEW was 27.3%, with 196 deaths observed during the mean follow-up of 25.5months. Patients with PEW who fulfilled at least 3 of the 4 listed criteria had a higher risk of death in the unadjusted model (hazard ratio 1.61, 95% confidence interval 1.19-2.18, P=.002). However, these associations were attenuated after adjusting for potential confounders. Regarding the individual PEW criterion, decreased serum albumin and low muscle mass were significantly associated with mortality in the multivariable models. In contrast, decreased body mass and low protein intake were not associated with a higher risk of death. High MIS (≥5 points) and each one-point increase in the MIS were also significantly associated with higher risk of death in both unadjusted and adjusted models. Among PD patients, the presence of PEW was not a better predictor of all-cause mortality than either the altered serum biochemistry (albumin) or low muscle mass criteria. The MIS performed well as an independent predictor of death and might be an option for assessment of PEW status in the PD population.