Associations of Protein-Energy Wasting Syndrome Criteria With Body Composition and Mortality in the General and Moderate Chronic Kidney Disease Populations in the United States

Study on the correlation between bioelectrical impedance analysis index and protein energy consumption in maintenance dialysis patients

BACKGROUND

Protein-energy wasting (PEW) has been reported to be pretty common in maintenance dialysis patients. However, the existing PEW diagnostic standard is limited in clinical use due to the complexity of it. Bioelectrical impedance analysis (BIA), as a non-invasive nutritional assessment method, can objectively and quantitatively analyze the changes of body tissue components under different nutritional states. We aim to explore the association between PEW and BIA and establish a reliable diagnostic model of PEW.

METHODS

We collected cross-sectional data of 609 maintenance dialysis patients at the First Affiliated Hospital, College of Medicine, Zhejiang University. PEW was diagnosed according to International Society of Renal Nutrition and Metabolism (ISRNM) criteria. Among them, 448 consecutive patients were included in the training set for the establishment of a diagnostic nomogram. 161 consecutive patients were included for internal validation. 52 patients from Zhejiang Hospital were included for external validation of the diagnostic model. Correlation analysis of BIA indexes with other nutritional indicators was performed. Logistic regression was used to examine the association of BIA indexes with PEW. 12 diagnostic models of PEW in maintenance dialysis patients were developed and the performance of them in terms of discrimination and calibration was evaluated using C statistics and Hosmer-Lemeshow-type χ2 statistics. After comparing to existing diagnostic models, and performing both internal and external validation, we finally established a simple but reliable PEW diagnostic model which may have great value of clinical application.

RESULTS

A total of 609 individuals from First Affiliated Hospital, College of Medicine, Zhejiang University and 52 individuals from Zhejiang Hospital were included. After full adjustment, age, peritoneal dialysis (compared to hemodialysis), subjective global assessment (SGA, compared to non-SGA) and water ratio were independent risk factors, while triglyceride, urea nitrogen, calcium, ferritin, BCM, VFA and phase angle were independent protective factors of PEW. The model incorporated water ratio, VFA, BCM, phase angle and cholesterol revealed best performance. A nomogram was developed according to the results of model performance. The model achieved high C-indexes of 0.843 in the training set, 0.841 and 0.829 in the internal and external validation sets, respectively, and had a well-fitted calibration curve. The net reclassification improvement (NRI) showed 8%, 13%, 2%, 38%, 36% improvement of diagnostic accuracy of our model compared with "PEW score model", "modified PEW score model", "3-index model", "SGA model" and "BIA decision tree model", respectively.

CONCLUSIONS

BIA can be used as an auxiliary tool to evaluate PEW risk and may have certain clinical application value.

Severity of protein-energy wasting and obesity are independently related with poor quality of life in peritoneal dialysis patients

Protein-energy wasting (PEW) and poor health-related quality of life (HRQoL) are independently associated with morbi-mortality in continuous ambulatory peritoneal dialysis (CAPD). PEW may reduce HRQoL; however, we hypothesized HRQoL is affected differentially by PEW degrees or by individual criteria of nutritional status. AIM: To evaluate HRQoL according to PEW severity and nutritional status indicators in CAPD. This is a cross-sectional study in 151 patients. Subjective global assessment (SGA) was employed, and nutritional status classified as normal, mild-moderate PEW, and severe PEW. HRQoL was evaluated using Kidney Disease Quality of Life Short Form™, including physical (PCS), mental (MCS) and kidney disease (KDCS) components, and their subscales. Dietary intake, anthropometric and biochemical variables were measured. Forty-six percent of patients were well-nourished, 44% had mild-moderate PEW, and 10% severe PEW. Compared with well-nourished patients, those with mild-moderate (p=0.06) and severe (p=0.005) PEW had lower HRQoL score [68 (52-75), 55 (45-72), 46 (43-58), respectively]. PCS, MCS, and KDCS and their subscales had lower values as PEW was more severe. Patients with obesity and hypoalbuminemia had significantly lower HRQoL overall and component scores than their counterparts. Dietary intake was not associated with quality of life. In multivariate analysis obesity, PEW (by SGA), hypoalbuminemia, and low educational level predicted poor HRQoL (χ² 58.2, p<0.0001). As conclusion, PEW severity was related with worse HRQoL, either as overall score or in every component or subscale in CAPD patients. Poor HRQoL was predicted independently by PEW severity and obesity; additional predictors were hypoalbuminemia and low education.

Protein energy wasting-based nutritional assessment predicts outcomes of acute ischemic stroke and solves the epidemiologic paradox

OBJECTIVE

Overweight and hyperlipidemia, the two established risk factors for acute ischemic stroke, are paradoxically associated with favorable outcomes. The paradox may be resolved by the concept of protein energy wasting (PEW), in which total cholesterol level and body mass index are used as nutritional indexes for predicting outcomes of chronic kidney disease.

METHODS

Among 12 271 people with acute ischemic stroke and chronic kidney disease, 2086 were defined as being at risk of PEW-with a body mass index <22 kg/m² plus either a serum albumin level <38 g/L or a total cholesterol level <4.14 mmol/L (160 mg/dL) without the use of lipid-lowering drugs-and all the others were a control group. The hazards of PEW for mortality and functional outcomes were evaluated using propensity score matching and multivariate Cox regression analysis.

RESULTS

Based on the propensity score, 2081 PEW participants were matched to the same number of non-PEW control participants. PEW was associated with a higher mortality risk at 3 mo (adjusted hazard ratio, 1.19; 95% confidence interval [CI], 1.02-1.42) and 1 y (adjusted hazard ratio, 1.33; 95% CI1.13-1.52). PEW was also associated with poor functional outcomes (modified Rankin Scale score >2) at 1 mo (adjusted odds ratio, 1.32; 95% CI, 1.08-1.61) and 3 mo (adjusted odds ratio, 1.27; 95% CI, 1.03-1.56).

CONCLUSIONS

According to the PEW-based assessment system, a modest decrease in body mass index and total cholesterol levels suggests malnutrition and is associated with adverse outcomes of acute ischemic stroke.

Predicational ability of phase angle on protein energy wasting in kidney disease patients with renal replacement therapy: A cross-sectional study

OBJECTIVE

To investigate the ability of phase angle (PA) and body composition for predicting protein energy wasting (PEW) in renal replacement therapy (RRT) patients.

METHODS

Renal replacement therapy (RRT) patients were enrolled in this study. Body composition was measured by direct segmental multi-frequency biolectrical impedance analysis method (DSM-BIA); phase angle (PA), fat-free mass (FFM), fat mass (FM), mid-arm circumference (MAC), WC (waist circumference), and ECW/TBW (extracellular water/total body water) were obtained. Biochemicals (serum albumin, triglyceride, and cholesterol) were tested. PEW patients were classified according to ISRNM (The International Society of Renal Nutrition and Metabolism) criteria. Cutoff value of PA and related variables was calculated by ROC analysis. The ability of body composition variables as indicators to predict PEW was evaluated.

RESULTS

Sixty-four patients were enrolled in this study. Thirty-three patients (52.6%) were males, and forty (62.5%) patients were diagnosed with PEW. The ROC curve showed that the optimal cutoff values of PA, FFMI (fat-free mass index), MAC, WC, and BMI for PEW risk were 4.45°, 16.71, 29.7 cm, 86.4 cm, and 21.1 kg/m2, respectively. These indicators showed significant association with PEW; meanwhile, the PA and MAC can be used as the predictors for PEW with OR 6.333 (95% CI, 1.956-20.505) and 3.267 (95% CI, 1.136-9.394), respectively. Both groups have a lower BUN/Cr ratio (<20).

CONCLUSION

In the RRT patients, over than 60% patients were diagnosed with PEW. PA, MAC, and other body composition can be used as the independent indicators for predicting PEW in renal replacement therapy kidney disease patients.

Severity of protein-energy wasting and obesity are independently related with poor quality of life in peritoneal dialysis patients

Protein-energy wasting (PEW) and poor health-related quality of life (HRQoL) are independently associated with morbi-mortality in continuous ambulatory peritoneal dialysis (CAPD). PEW may reduce HRQoL; however, we hypothesized HRQoL is affected differentially by PEW degrees or by individual criteria of nutritional status. AIM: To evaluate HRQoL according to PEW severity and nutritional status indicators in CAPD. This is a cross-sectional study in 151 patients. Subjective global assessment (SGA) was employed, and nutritional status classified as normal, mild-moderate PEW, and severe PEW. HRQoL was evaluated using Kidney Disease Quality of Life Short Form™, including physical (PCS), mental (MCS) and kidney disease (KDCS) components, and their subscales. Dietary intake, anthropometric and biochemical variables were measured. Forty-six percent of patients were well-nourished, 44% had mild-moderate PEW, and 10% severe PEW. Compared with well-nourished patients, those with mild-moderate (p=0.06) and severe (p=0.005) PEW had lower HRQoL score [68 (52-75), 55 (45-72), 46 (43-58), respectively]. PCS, MCS, and KDCS and their subscales had lower values as PEW was more severe. Patients with obesity and hypoalbuminemia had significantly lower HRQoL overall and component scores than their counterparts. Dietary intake was not associated with quality of life. In multivariate analysis obesity, PEW (by SGA), hypoalbuminemia, and low educational level predicted poor HRQoL (χ2 58.2, p<0.0001). As conclusion, PEW severity was related with worse HRQoL, either as overall score or in every component or subscale in CAPD patients. Poor HRQoL was predicted independently by PEW severity and obesity; additional predictors were hypoalbuminemia and low education.

Muscle-Bone Crosstalk in Chronic Kidney Disease: The Potential Modulatory Effects of Exercise

Chronic kidney disease (CKD) is a prevalent worldwide public burden that increasingly compromises overall health as the disease progresses. Two of the most negatively affected tissues are bone and skeletal muscle, with CKD negatively impacting their structure, function and activity, impairing the quality of life of these patients and contributing to morbidity and mortality. Whereas skeletal health in this population has conventionally been associated with bone and mineral disorders, sarcopenia has been observed to impact skeletal muscle health in CKD. Indeed, bone and muscle tissues are linked anatomically and physiologically, and together regulate functional and metabolic mechanisms. With the initial crosstalk between the skeleton and muscle proposed to explain bone formation through muscle contraction, it is now understood that this communication occurs through the interaction of myokines and osteokines, with the skeletal muscle secretome playing a pivotal role in the regulation of bone activity. Regular exercise has been reported to be beneficial to overall health. Also, the positive regulatory effect that exercise has been proposed to have on bone and muscle anatomical, functional, and metabolic activity has led to the proposal of regular physical exercise as a therapeutic strategy for muscle and bone-related disorders. The detection of bone- and muscle-derived cytokine secretion following physical exercise has strengthened the idea of a cross communication between these organs. Hence, this review presents an overview of the impact of CKD in bone and skeletal muscle, and narrates how these tissues intrinsically communicate with each other, with focus on the potential effect of exercise in the modulation of this intercommunication.

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

OBJECTIVES

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.

METHODS

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 <3.5 g/L; (2) decreased body mass status identified by a body mass index (BMI) of <23 kg/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 <0.8 g/kg/day. The Malnutrition Inflammation Score (MIS) was also examined as an alternative tool for assessment of PEW.

RESULTS

The average age of the 555 participants was 57.5 ± 12.6 years. The prevalence of PEW was 27.3%, with 196 deaths observed during the mean follow-up of 25.5 months. 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.

CONCLUSIONS

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.

Association of bioimpedance-derived 50-kHz phase angle as marker of body composition with electrical parameters regarding the Cole-Cole model

Our aim is to clarify the association of the bioelectrical impedance-derived 50-kHz phase angle (φ₅₀ ) with electrical parameters regarding the Cole-Cole model and clinical parameters. A total of 440 sets of bioelectrical impedance data from pre- and post-hemodialysis from 157 patients were used. Resistance at infinite frequency (R_inf ), resistance at 0 frequency (R₀ ), capacitance of the cell membrane (Cm), and a parameter for the distribution of the time constant (α) were examined as electrical parameters. Normally hydrated lean tissue mass as a percentage of the dry weight (P_NHLT ), excess fluid mass as a percentage of the dry weight (P_ExF ), body mass index (BMI), age, and sex (N_sex , 0 for male, 1 for female) were examined as clinical parameters. φ₅₀ increased with the decrease in R_inf /R₀ and α and also with the increase in Cm (multiple regression coefficients [β]: pre/post, -0.886/-0.936, -0.175/-0.212, and 0.167/0.141), which determined the ratio of intra- to extracellular fluid volume (ICV/ECV), tissue homogeneity, and total cell mass. φ₅₀ increased with an increase in P_NHLT and BMI and decrease in P_ExF , N_sex , and age (β: pre/post, 0.654/0.581, 0.466/0.412, -0.483/-0.473, -0.216/-0.154, and -0.145/-0.127). The concordance correlation coefficient between φ₅₀ for pre- and post-hemodialysis (ρ = 0.772) may be improved (ρ = 0.950) by adding a multiplication of 0.2 and P_ExF to φ₅₀ for correction. φ₅₀ may be used to estimate body composition through the association with ICV/ECV, tissue homogeneity, and total cell mass. The correction for excess fluid is essential in order to use φ₅₀ as a marker of body composition related to nutrition.

Circulating Endocannabinoids and Mortality in Hemodialysis Patients

BACKGROUND

Mortality in patients with end-stage renal disease (ESRD) on maintenance hemodialysis (MHD) remains exceptionally high. While traditional risk factors such as obesity are paradoxically associated with better survival, nontraditional risk factors including cachexia increase the likelihood of poor outcomes. There is accumulating evidence that the endocannabinoid (ECB) system plays a major role in energy preservation and storage, factors which can prevent the deleterious effects of cachexia. Hence, in this study, we evaluated the association of circulating ECB levels with mortality in MHD patients.

METHODS

Serum concentrations of anandamide (AEA) and 2-arachidonoyl-sn-glycerol (2-AG), major ECB ligands, were measured in MHD patients. Their correlation with various clinical/laboratory indices and association with 12-month all-cause mortality were examined.

RESULTS

Serum 2-AG levels positively correlated with body mass index, serum triglycerides and body anthropometric measures. Meanwhile, serum AEA levels correlated positively with serum interleukin-6, and negatively with serum very low-density lipoprotein levels. While increased serum 2-AG levels were associated with reduced risk of all-cause mortality (hazard ratio [HR] 0.52, 95% CI 0.28-0.98), there was no clear association between serum AEA levels and mortality (HR 0.91, 95% CI 0.48-1.72).

CONCLUSIONS

In MHD patients, the circulating levels of ECB ligand, 2-AG, may play an important role in determining body mass and risk of mortality. These observations were unique to 2-AG as similar findings were not obtained with serum AEA. Future studies need to investigate the mechanisms responsible for these associations and examine the modulation of the ECB system as a potential target for therapy in ESRD.

Effect of Oral Nutritional Supplementation With and Without Exercise on Nutritional Status and Physical Function of Adult Hemodialysis Patients: A Parallel Controlled Clinical Trial (AVANTE-HEMO Study)

OBJECTIVE

Protein energy wasting affects the nutritional status (NS) and physical function (PF) of dialysis patients. Among the different anabolic strategies to improve NS and PF, oral nutritional supplementation (ONS) and resistance exercise (RE) or aerobic exercise (AE) have been shown to be effective. Nevertheless, the combination of both anabolic strategies has not been completely evaluated. The aim of this study is to assess the effect of exercise combined with ONS versus ONS without exercise during hemodialysis sessions on PF and NS indicators.

METHODS

Young hemodialysis patients (29 ± 9.3 years) with predominantly unknown causes of renal disease (80%) were divided into the following 3 groups during a period of 12 weeks: (1) ONS (n = 15), (2) ONS + RE (n = 15), and (3) ONS + AE (n = 15). Anthropometric, biochemical, PF, and quality of life measurements were recorded at baseline and after 3 months. Repeated measures analysis of variance and effect sizes (Cohen's d) were used to assess the effect of exercise and nutrition (ISRCTN registry 10251828).

RESULTS

At the completion of the study, the ONS and ONS + RE groups exhibited statistically significant increases in body weight, body mass index, and in the percentage of fat mass (P < .05); the greatest effect sizes were observed in the ONS + RE group (d = 0.30 for body weight, d = 0.63 for body mass index, and d = 0.90 for the percentage of fat mass). Groups with RE and AE had statistically significant increases and large effect sizes in the six-minute walk test (RE: d = 0.94, P = .02; AE: d = 1.11, P = .03), sit-to-stand test (RE: d = 0.81, P = .041; AE: d = 1.20, P = .002), timed up and go test (RE: d = 1.04, P = .036; AE: d = 1.6, P = .000), and muscle strength (RE: d = 1.01, P = .000; AE: d = 0.60, P = .003). Regarding quality of life, the ONS + RE group had more areas of improvement at the end of the study, followed by the ONS + AE group. No statistically significant differences were found in the repeated measures ANOVA.

CONCLUSIONS

The combination of exercise with ONS had larger effects on PF than on ONS alone. Further studies to examine the impact of exercise on the effect of oral nutritional supplementation in dialysis patients are indicated.

Effects of intradialytic resistance exercise on systemic inflammation in maintenance hemodialysis patients with sarcopenia: a randomized controlled trial

PURPOSE

To investigate the effect of intradialytic resistance exercise on inflammation markers and sarcopenia indices in maintenance hemodialysis (MHD) patients with sarcopenia.

METHODS

Forty-one MHD patients with sarcopenia were divided into an intervention group (group E, n = 21) and a control group (group C, n = 20). Group C patients only received routine hemodialysis care, whereas group E patients received progressive intradialytic resistance exercise with high or moderate intensity for 12 weeks at three times per week (using the weight of the lower limbs and elastic ball movement of the upper limb) on the basis of routine hemodialysis care.

RESULTS

After 12 weeks, a significant difference in physical activity status (maximum grip strength, daily pace, and physical activity level), Kt/V, and C-reactive protein was found between groups E and C. Inflammatory factors (interleukin (IL)-6, IL-10, and tumor necrosis factor(TNF)-α) increased or decreased more significantly in group E than in group C.

CONCLUSIONS

This study showed that intradialytic resistance exercise can improve physical activity effectively and reduce microinflammatory reactions even if this simple exercise does not affect the muscle mass in MHD patients with sarcopenia.

Kidney cachexia or protein-energy wasting in chronic kidney disease: facts and numbers

BACKGROUND

Weight loss and homeostatic disturbances of both energy and protein balances are characteristics of several illnesses including cancer, heart failure, and chronic kidney disease (CKD). Different definitions have been used to describe this deleterious process. The term protein-energy wasting (PEW) has been proposed for CKD patients by the International Society of Renal Nutrition and Metabolism.

METHODS

We searched the publication in Medline from February 2008 to September 2018 using PEW or cachexia in their title.

RESULTS

Since its inception, the term PEW has been exceptionally successful, highlighted by 327 original publications referenced in PubMed over 10 years. Using this classification, several studies have confirmed that PEW is among the strongest predictors of mortality in CKD patients [hazard ratio of 3.03; confidence interval of 1.69-5.26 in 1068 haemodialysis patients and 1.40 (1.04-1.89) in 1487 non-dialysed patients across PEW stages 0 to 4]. Based on this classification, prevalence of PEW is 28% to 54% among 16 434 adults undergoing maintenance dialysis. PEW prevalence increases when renal function declines, that is, from <2% in CKD stages 1-2 to 11-54% in CKD stages 3-5. A more general definition of cachexia for all chronic diseases proposed by the Society on Sarcopenia, Cachexia and Wasting Disorders was also published concurrently. In the CKD area, we found 180 publications using 'cachexia' underlining that some confusion or overlap may exist. The definitions of PEW and cachexia are somewhat similar, and the main difference is that a loss of body weight >5% is a mandatory criterion for cachexia but supportive for PEW.

CONCLUSIONS

The recent understanding of cachexia physiopathology during CKD progression suggests that PEW and cachexia are closely related and that PEW corresponds the initial state of a continuous process that leads to cachexia, implicating the same metabolic pathways as in other chronic diseases. Despite the success of the definition of PEW, using a more uniform term such as 'kidney disease cachexia' could be more helpful to design future research through collaborative groups of researchers with focus on cachexia.

Influence of dietary protein intake on body composition in chronic kidney disease patients in stages 3-5: A cross-sectional study

INTRODUCTION

A controlled protein intake has shown beneficial effects to preserve renal function and nutritional status in chronic kidney disease (CKD) patients. This study aimed to analyze usual dietary protein intake and its potential contribution to body composition in CKD patients in stages 3-5.

METHOD

Cross-sectional study in 134 CKD patients in stages 3-5 (mean e-GFR: 19.4±8.7ml/min/1.73m²; males 68.7% and primary CKD etiology was diabetes mellitus, 35.8%). Demographic, clinical and nutritional parameters were evaluated. Normalized protein nitrogen appearance (nPNA), was used as a surrogate marker of dietary protein intake. The sample was classified into three nPNA groups (G_n): G₁: <0.8g/kg/day; G₂: 0.8-1g/kg/day and, G₃: ≥1g/kg/day. Assessment of nutritional status using the malnutrition-inflammation score (MIS), anthropometric measures and laboratory parameters. Analysis of body composition and hydration status by bioelectrical impedance analysis (BIVA-101-RJL system). Statistical analysis by SPSS v.20.

RESULTS

Overall mean nPNA values were 0.91±0.23g of protein/kg BW/day and only 32.1% had a dietary protein intake <0.8g of protein/kg BW/day. Most of the CKD patients (65.5%) were in stages 4 or 5. Prevalence of protein-energy-wasting (PEW) syndrome measured by MIS was 15%. By analyzing differences between nPNA groups, body weight (BW), BMI and triceps-skinfold (TSF) thickness were significantly higher in the group with nPNA ≥1g/kg BW/day (G₃), whereas a significant inverse relationship was found with the percentages of body cell mass (BCM%), fat-free mass (FFM%), muscle mass (MM%) and phase angle (PA) in the group with the lowest nPNA (G₁). Analysis of gender among subjects showed significant differences with BW, FFM%, TSF and mid-arm muscle circumference (MAMC%). Linear regression analysis showed that resistance, BCM%, MM%, and serum albumin were significant predictors of nPNA as a surrogate marker of daily protein intake (R=0.51; R²=0.29; R² adjusted=0.23; p<0.001).

CONCLUSION

Controlled protein intake is one of the cornerstones of treatment in CKD patients. A low protein intake in patients with CKD stages 3 and 4-5 was associated with loss of muscle mass in the advanced-CKD unit. The loss of muscle mass appears as an early indicator of nutritional comprised. Factors such, elderly age and loss of eGFR, showed lower protein intake and were associated with muscle loss, especially in women. Further longitudinal studies are required to evaluate the contribution of different protein intakes to uremic symptoms, nutritional status, body composition and CKD progression.

Diagnostic Usefulness of the Protein Energy Wasting Score in Prevalent Hemodialysis Patients

OBJECTIVE

To study whether the score proposed by the International Society of Renal Nutrition and Metabolism to define the protein energy wasting (PEW) syndrome has diagnostic validity in patients undergoing dialysis.

DESIGN AND METHODS

Cross-sectional study including 468 prevalent hemodialysis patients from Canary Islands, Spain. Individual PEW syndrome criteria and the number of PEW syndrome categories were related to other objective markers of PEW using linear and logistic regression analyses: subjective global assessment, handgrip strength, bioimpedance-assessed body composition, and levels of high-sensitivity C-reactive protein.

RESULTS

Study participants (34% women) had a median age of 66 years, 37 months of maintenance dialysis, and 50% were diabetics. About 23% of patients had PEW (≥3 PEW categories), and 68% were at risk of PEW (1-2 PEW categories). Low prealbumin was the most frequently found derangement (52% of cases), followed by low albumin (46%), and low protein intake (35%). Across higher number of PEW syndrome categories, patients showed a longer dialysis vintage and had lower creatinine, triglycerides, and transferrin (P for trend <.001 for all). All nutritional assessments not included in the PEW definition worsened across higher number of PEW categories. In multivariable regression analyses, there was a linear inverse relationship between muscle and fat mass as well as handgrip strength with the number of PEW syndrome categories. Likewise, the proportion of subjective global assessment-defined malnutrition and serum concentration of C-reactive protein gradually increased despite adjustment for confounders (P for trend <.05 for all).

CONCLUSION

The PEW score reflects systemic inflammation, malnutrition and wasting among dialysis patients and may thus be used for diagnostic purposes.

Low Protein Intake in the Population: Low Risk of Kidney Function Decline but High Risk of Mortality

OBJECTIVE

This population-based study investigated low protein intake, mortality, and kidney function decline.

DESIGN

Observational longitudinal cohort study.

SUBJECTS

Target cohort consisted of 4,679 adults participating in 1988-1992 and 2001-2007 examinations of the Gubbio Study (baseline and follow-up). Data collection included overnight urine urea nitrogen (UUN) and other variables at baseline, serum creatinine at baseline and follow-up, and mortality from baseline to follow-up. Three hundred seventy-two persons were excluded for missing data. UUN in the lowest 20% of the distribution was defined as low and used as index of low protein intake. Estimated glomerular filtration rate (eGFR, mL/minute × 1.73 m²) was used as kidney function index.

INTERVENTION

None (observational study).

MAIN OUTCOME MEASURE

Mortality and eGFR decline are the main outcome measures, and eGFR decline was defined as eGFR change from baseline to follow-up ≤ mean-1 standard deviation (Z-score ≤ -1).

RESULTS

Eight hundred seventy-one deaths occurred over 15.9 ± 4.0 years of observation (417 from cardiovascular disease and 276 from neoplastic disease). Low UUN associated with mortality (hazard ratio, HR = 1.31, 95% confidence interval, CI = 1.12/1.53) due to association with mortality from neoplastic disease (HR = 1.33, 95% CI = 1.02/1.76). Mortality-corrected follow-up response rate was 79.9% (n = 2845). Baseline to follow-up eGFR change was -9.9 ± 10.1, and eGFR decline was found in 454 examinees. Low UUN associated with eGFR decline only in subgroup with baseline eGFR <90 (n = 1441, odds ratio = 0.44, 95% CI = 0.22/0.85). Low baseline eGFR interacted with the association between low UUN and eGFR decline (P = .024).

CONCLUSION

Low protein intake predicted higher mortality in the whole population and lower incidence of eGFR decline only in subgroup with reduced kidney function.