Longitudinal Changes in Body Composition in Patients After Initiation of Hemodialysis Therapy: Results From an International Cohort

Association of changes in body composition with all-cause mortality in patients undergoing hemodialysis: A prospective cohort study

OBJECTIVES

This study aimed to explore the effect of longitudinal body composition changes on mortality risk in patients undergoing hemodialysis and identify whether changes in body composition can more accurately predict mortality than baseline status.

METHODS

A prospective cohort study was conducted on 340 patients undergoing hemodialysis. Lean mass and body fat were determined using a bioimpedance spectroscopy (BIS) device and expressed as the lean tissue index (LTI) or fat tissue index (FTI), respectively. The patients were subjected to BIS at baseline and after 1 year. The hazard ratio (HR) for death was calculated using Cox regression analysis.

RESULTS

Among 340 patients, 289 were tested with a repeat BIS. LTI loss and FTI gain were observed in 51.2% and 47.1% of the patients, respectively. Low baseline LTI was a significant predictor of all-cause mortality after adjusting for demographic and biochemical parameters (HR, 2.41; P = 0.047), but not when comorbidities were included in the multivariate analysis. However, after adjusting for various confounding factors, LTI loss (HR, 3.40; P = 0.039) and FTI gain (HR, 4.06; P = 0.024) were independent risk factors for all-cause mortality, and the adjusted HR for LTI loss and FTI gain vs. no LTI loss and no FTI gain was 5.34 (P = 0.016).

CONCLUSIONS

LTI loss and FTI gain, particularly their combination, are important predictors of survival in patients undergoing hemodialysis. Our results emphasize that longitudinal changes in LTI and FTI are more strongly associated with all-cause mortality than single-point values. Therefore, it is important to dynamically assess the muscle and fat tissues and develop potential targeted treatment strategies for this population.

Nutritional Assessments by Bioimpedance Technique in Dialysis Patients

Bioelectrical impedance analysis (BIA) has been extensively applied in nutritional assessments on the general population, and it is recommended in establishing the diagnosis of malnutrition and sarcopenia. The bioimpedance technique has become a promising modality through which to measure the whole-body composition in dialysis patients, where the presence of subclinical volume overload and sarcopenic obesity may be overlooked by assessing body weight alone. In the past two decades, bioimpedance devices have evolved from applying a single frequency to a range of frequencies (bioimpedance spectroscopy, BIS), in which the latter is incorporated with a three-compartment model that allows for the simultaneous measurement of the volume of overhydration, adipose tissue mass (ATM), and lean tissue mass (LTM). However, clinicians should be aware of common potential limitations, such as the adoption of population-specific prediction equations in some BIA devices. Inherent prediction error does exist in the bioimpedance technique, but the extent to which this error becomes clinically significant remains to be determined. Importantly, reduction in LTM has been associated with increased risk of frailty, hospitalization, and mortality in dialysis patients, whereas the prognostic value of ATM remains debatable. Further studies are needed to determine whether modifications of bioimpedance-derived body composition parameters through nutrition intervention can result in clinical benefits.

Application of Bioelectrical Impedance Analysis in Nutritional Management of Patients with Chronic Kidney Disease

Body composition measurement plays an important role in the nutritional diagnosis and treatment of diseases. In the past 30 years, the detection of body composition based on bioelectrical impedance analysis (BIA) has been widely used and explored in a variety of diseases. With the development of technology, bioelectrical impedance analysis has gradually developed from single-frequency BIA (SF-BIA) to multi-frequency BIA (multi-frequency BIA, MF-BIA) and over a range of frequencies (bioimpedance spectroscopy, BIS). As the clinical significance of nutrition management in chronic kidney disease has gradually become prominent, body composition measurement by BIA has been favored by nephrologists and nutritionists. In the past 20 years, there have been many studies on the application of BIA in patients with CKD. This review describes and summarizes the latest research results of BIA in nutritional management of patients with CKD including pre-dialysis, hemodialysis, peritoneal dialysis and kidney transplantation, in order to provide reference for the application and research of BIA in nutritional management of chronic kidney disease in the future.

Effects of anthropometric changes on hospitalization and mortality among patients on hemodialysis

BACKGROUND

Low values for anthropometric indicators are risk factors for adverse clinical outcomes among patients on hemodialysis. Nonetheless, little is known about the association between the trajectory of anthropometric indicators and prognosis. We examined the association between a one-year change in anthropometric indicators and hospitalization and mortality in patients undergoing hemodialysis.

METHODS

This retrospective cohort study collected data on five anthropometric indicators from patients undergoing maintenance hemodialysis: body mass index, mid-upper arm circumference, triceps skinfold, mid-arm muscle circumference, and calf circumference. We calculated their trajectories over one year. The outcomes were all-cause death and the number of all-cause hospitalizations. Negative binomial regressions were used to examine these associations.

RESULTS

We included 283 patients (mean age, 67.3 years; 60.4% males). During the follow-up period (median, 2.7 years), 30 deaths and 200 hospitalizations occurred. Body mass index (incident rate ratio [IRR]: 0.87; 95% confidence interval [CI] 0.85-0.90), mid-upper arm circumference (IRR: 0.94; 95% CI 0.88-0.99), triceps skinfold (IRR: 0.92; 95% CI 0.84-0.99), and mid-arm muscle circumference (IRR: 0.99; 95% CI 0.98-0.99) increases over one year were associated with a lower risk of all-cause hospitalizations and death regardless of their value at any one point in time. However, the calf circumference trajectory was not associated with clinical events (IRR: 0.94; 95% CI 0.83-1.07).

CONCLUSIONS

Body mass index, mid-upper arm circumference, triceps skinfold, and mid-arm muscle circumference trajectories were independently associated with clinical events. Routinely assessing these simple measures in clinical practice may provide additional prognostic information for managing patients undergoing hemodialysis.

Intradialytic plantar electrical nerve stimulation to improve mobility and plantar sensation among adults with diabetes undergoing hemodialysis: a randomized double-blind trial

BACKGROUND

Impaired mobility is a debilitating consequence of hemodialysis. We examined the efficacy of intradialytic-plantar-electrical-nerve-stimulation (iPENS) to promote mobility among diabetes patients undergoing hemodialysis..

METHODS

Adults with diabetes undergoing hemodialysis received either 1-h active iPENS, (Intervention-Group) or non-functional iPENS (Control-Group) during routine hemodialysis for 12 weeks (3 sessions/week). Participants and care-providers were blinded. Mobility (assessed using a validated pendant-sensor) and neuropathy (quantified by vibration-perception-threshold test) outcomes were assessed at baseline and 12 weeks.

RESULTS

Among 77 enrolled subjects (56.2 ± 2.6 years old), 39 were randomly assigned to the intervention group, while 38 were assigned to the control group. No study-related adverse events and dropouts were reported in the intervention group. Compared to the control group, significant improvements with medium to large effect sizes were observed in the intervention group at 12 weeks for mobility-performance metrics, including active-behavior, sedentary-behavior, daily step counts, and sit-to-stand duration variability (p < 0.05), Cohen's d effect size (d = 0.63-0.84). The magnitude of improvement in active-behavior was correlated with improvement in the vibration-perception-threshold test in the intervention group (r = - 0.33, p = 0.048). A subgroup with severe-neuropathy (vibration-perception-threshold > 25 V) showed a significant reduction in plantar numbness at 12 weeks compared to baseline (p = 0.03, d = 1.1).

CONCLUSIONS

This study supports feasibility, acceptability, and effectiveness of iPENS to improve mobility and potentially reduce plantar numbness in people with diabetes undergoing hemodialysis. Considering that exercise programs are not widely used in hemodialysis clinical practice, iPENS may serve as a practical, alternative solution to reduce hemodialysis-acquired weakness and promote mobility.

Intradialytic Protein Ingestion and Exercise do Not Compromise Uremic Toxin Removal Throughout Hemodialysis

OBJECTIVE

Dietary protein and physical activity interventions are increasingly implemented during hemodialysis to support muscle maintenance in patients with end-stage renal disease (ESRD). Although muscle maintenance is important, adequate removal of uremic toxins throughout hemodialysis is the primary concern for patients. It remains to be established whether intradialytic protein ingestion and/or exercise modulate uremic toxin removal during hemodialysis.

METHODS

We recruited 10 patients with ESRD (age: 65 ± 16 y, BMI: 24.2 ± 4.8 kg/m²) on chronic hemodialysis treatment to participate in this randomized cross-over trial. During hemodialysis, patients were assigned to ingest 40 g protein or a nonprotein placebo both at rest (protein [PRO] and placebo [PLA], respectively) and following 30 min of exercise (PRO + exercise [EX] and PLA + EX, respectively). Blood and spent dialysate samples were collected throughout hemodialysis to assess reduction ratios and removal of urea, creatinine, phosphate, cystatin C, and indoxyl sulfate.

RESULTS

The reduction ratios of urea and indoxyl sulfate were higher during PLA (76 ± 6% and 46 ± 9%, respectively) and PLA + EX interventions (77 ± 5% and 45 ± 10%, respectively) when compared to PRO (72 ± 4% and 40 ± 8%, respectively) and PRO + EX interventions (73 ± 4% and 43 ± 7%, respectively; protein effect: P = .001 and P = .023, respectively; exercise effect: P = .25 and P = .52, respectively). Nonetheless, protein ingestion resulted in greater urea removal (P = .046) during hemodialysis. Reduction ratios and removal of creatinine, phosphate, and cystatin C during hemodialysis did not differ following intradialytic protein ingestion or exercise (protein effect: P > .05; exercise effect: P>.05). Urea, creatinine, and phosphate removal were greater throughout the period with intradialytic exercise during PLA + EX and PRO + EX interventions when compared to the same period during PLA and PRO interventions (exercise effect: P = .034, P = .039, and P = .022, respectively).

CONCLUSION

The removal of uremic toxins is not compromised by protein feeding and/or exercise implementation during hemodialysis in patients with ESRD.

Fluid Overload and Tissue Sodium Accumulation as Main Drivers of Protein Energy Malnutrition in Dialysis Patients

Protein energy malnutrition is recognized as a leading cause of morbidity and mortality in dialysis patients. Protein-energy-wasting process is observed in about 45% of the dialysis population using common biomarkers worldwide. Although several factors are implicated in protein energy wasting, inflammation and oxidative stress mechanisms play a central role in this pathogenic process. In this in-depth review, we analyzed the implication of sodium and water accumulation, as well as the role of fluid overload and fluid management, as major contributors to protein-energy-wasting process. Fluid overload and fluid depletion mimic a tide up and down phenomenon that contributes to inducing hypercatabolism and stimulates oxidation phosphorylation mechanisms at the cellular level in particular muscles. This endogenous metabolic water production may contribute to hyponatremia. In addition, salt tissue accumulation likely contributes to hypercatabolic state through locally inflammatory and immune-mediated mechanisms but also contributes to the perturbation of hormone receptors (i.e., insulin or growth hormone resistance). It is time to act more precisely on sodium and fluid imbalance to mitigate both nutritional and cardiovascular risks. Personalized management of sodium and fluid, using available tools including sodium management tool, has the potential to more adequately restore sodium and water homeostasis and to improve nutritional status and outcomes of dialysis patients.

Body composition is associated with tacrolimus pharmacokinetics in kidney transplant recipients

PURPOSE

A population pharmacokinetic (popPK) model may be used to improve tacrolimus dosing and minimize under- and overexposure in kidney transplant recipients. It is unknown how body composition parameters relate to tacrolimus pharmacokinetics and which parameter correlates best with tacrolimus exposure. The aims of this study were to investigate which body composition parameter has the best association with the pharmacokinetics of tacrolimus and to describe this relationship in a popPK model.

METHODS

Body composition was assessed using bio-impedance spectroscopy (BIS). Pharmacokinetic analysis was performed using nonlinear mixed effects modeling (NONMEM). Lean tissue mass, adipose tissue mass, over-hydration, and phase angle were measured with BIS and then evaluated as covariates. The final popPK model was evaluated using goodness-of-fit plots, visual predictive checks, and a bootstrap analysis.

RESULTS

In 46 kidney transplant recipients, 284 tacrolimus concentrations were measured. The base model without body composition parameters included age, plasma albumin, plasma creatinine, CYP3A4 and CYP3A5 genotypes, and hematocrit as covariates. After full forward inclusion and backward elimination, only the effect of the phase angle on clearance (dOFV =  - 13.406; p < 0.01) was included in the final model. Phase angle was positively correlated with tacrolimus clearance. The inter-individual variability decreased from 41.7% in the base model to 34.2% in the final model. The model was successfully validated.

CONCLUSION

The phase angle is the bio-impedance spectroscopic parameter that correlates best with tacrolimus pharmacokinetics. Incorporation of the phase angle in a popPK model can improve the prediction of an individual's tacrolimus dose requirement after transplantation.

Intradialytic parenteral nutrition for patients on hemodialysis: when, how and to whom?

Hemodialysis is associated with high morbidity and mortality rates as well as low quality of life. Altered nutritional status and protein-energy wasting are important indicators of these risks. Maintaining optimal nutritional status in patients with hemodialysis is a critical but sometimes overlooked aspect of care. Nutritional support strategies usually begin with dietary counseling and oral nutritional supplements. Patients may not comply with this advice or oral nutritional supplements, however , or compliance may be affected by other complications of progressive chronic kidney disease. Intradialytic parenteral nutrition (IDPN) may be a possibility in these cases, but lack of knowledge on practical aspects of IDPN delivery are seldom discussed and may represent a barrier. In this review, we, as a consensus panel of clinicians experienced with IDPN, survey existing literature and summarize our views on when to use IDPN, which patients may be best suited for IDPN, and how to effectively deliver and monitor this strategy for nutritional support.

Can Overnutrition Lead to Wasting?-The Paradox of Diabetes Mellitus in End-Stage Renal Disease Treated with Maintenance Hemodialysis

Background: The population of end-stage renal disease (ESRD) patients with diabetes mellitus (DM) may be at increased risk of protein energy wasting (PEW). The aim of the study was to investigate the impact of DM on selected indicators of PEW in the ESRD population that was undergoing maintenance hemodialysis (MHD). Methods: A total of 515 MHD patients were divided into two subgroups with and without DM. The evaluation of diet composition, Charlson Comorbidity Index (CCI), SGA, and laboratory and BIS analyses were performed. All-cause and cardiovascular mortality was recorded. Results: DM patients had lower albumin (3.93 (3.61–4.20) vs. 4.10 (3.80–4.30) g/dL, p < 0.01), total cholesterol (158 (133–196) vs. 180 (148–206) mg/dL, p < 0.01), and creatinine (6.34 (5.08–7.33) vs. 7.12 (5.70–8.51) mg/dL, p < 0.05). SGA score (12.0 (10.0–15.0) vs. 11.0 (9.0–13.0) points, p < 0.001), BMI (27.9 (24.4–31.8) vs. 25.6 (22.9–28.8) kg/m², p < 0.001), fat tissue index (15.0 (11.4–19.6) vs. 12.8 (9.6–16.0) %, p < 0.001), and overhydration (2.1 (1.2–4.1) vs. 1.8 (0.7, 2.7) L, p < 0.001) were higher in the DM group. Increased morbidity, reflected in the CCI and mortality—both all-cause and cardiovascular—were observed in DM patients. Conclusions: Hemodialysis recipients with DM experience overnutrition with a paradoxically higher predisposition to PEW, expressed by a higher SGA score and lower serum markers of nutrition. This population is also more comorbid and is at higher risk of death, including from cardiovascular causes.

The impact of muscle mass loss and deteriorating physical function on prognosis in patients receiving hemodialysis

Muscle mass loss and worsening physical function are crucial issues in patients receiving hemodialysis (HD). However, few studies have investigated the association between temporal changes in muscle mass and physical function in a large number of HD patients. We examined 286 patients receiving HD (males, 58%; age, 66.8 ± 13.0 years) at a single center, and calculated the percent changes in psoas muscle mass index (%PMI) using computed tomography over two screenings, once per year (July 2011–June 2013). Physical function was evaluated using the Eastern Cooperative Oncology Group Performance Status (ECOG-PS) (range 0–4). The observation period was from July 2012 to June 2021. The median %PMI was -9.5%, and those with the lowest quartile of %PMI (< −20.5%) showed a significantly poor prognosis compared with other patients (p < 0.001). Multivariable logistic regression analysis revealed that these patients tended to have decreased physical function (ECOG-PS 2–4) [odds ratio (OR): 2.46, p < 0.001] and albumin levels (OR: 0.22, p = 0.007). Multiple-factor-adjusted Cox regression analyses showed that %PMI (hazard ratio: 0.99, p = 0.004) and each ECOG-PS stage (1–4 vs. 0) (p < 0.01) were associated with mortality. Augmenting physical activities in daily life and serum albumin levels should be considered to maintain muscle mass and improve the prognosis of patients receiving HD.

Comparison of Body Composition, Strength, and Physical Performance Measurements Between Healthy Participants and Hemodialysis Patients

Purpose

This study evaluated the difference in physical performance tests, strength, and total and regional mass using a comprehensive dataset between maintenance hemodialysis (HD) patients and a healthy population.

Patients and Methods

A total of 84 HD patients were enrolled. We selected 42 healthy participants (HPs) age- and sex-matched to the 84 HD patients as controls. Collected data were sex, age, body mass index (BMI), laboratory findings, total and regional measurements for lean mass or fat mass, thigh muscle area (TMA), handgrip strength, and physical performance measurements.

Results

There were no significant differences in BMI, total lean mass, or total fat mass including regional fat mass between the two groups. Lean leg mass and TMA were greater in HPs than in HD patients. All measurements of physical performance, including handgrip strength, were better in HPs than in HD patients. A multivariate analysis of lean leg mass, TMA, and physical performance measures had similar results to the same data studied with a univariate analysis.

Conclusion

We demonstrated that HD patients had decreased physical performance and strength compared to HPs. The difference in leg muscle mass was most prominent among the total and regional body compositions between HPs and HD patients.

Amino acid removal during hemodialysis can be compensated for by protein ingestion and is not compromised by intradialytic exercise: a randomized controlled crossover trial

BACKGROUND

Patients with end-stage renal disease (ESRD) undergoing hemodialysis experience a rapid decline in skeletal muscle mass and strength. Hemodialysis removes amino acids (AAs) from the circulation, thereby lowering plasma AA concentrations and stimulating proteolysis.

OBJECTIVES

In the present study, we evaluate the impact of intradialytic protein ingestion at rest and following exercise on AA removal and plasma AA availability in patients with ESRD.

METHODS

Ten patients (age: 65 ± 16 y, male/female: 8/2, BMI: 24.2 ± 4.8 kg/m2, serum albumin: 3.4 ± 0.3 g/dL) with ESRD undergoing hemodialysis participated in this randomized controlled crossover trial. During 4 hemodialysis sessions, patients were assigned to ingest 40 g protein or a placebo 60 min after initiation, both at rest (PRO and PLA, respectively) and following exercise (PRO + EX and PLA + EX, respectively). Spent dialysate and blood samples were collected every 30 min throughout hemodialysis to assess AA removal and plasma AA availability.

RESULTS

Plasma AA concentrations declined by 26.1 ± 4.5% within 30 min after hemodialysis initiation during all interventions (P < 0.001, η2p > 0.79). Protein ingestion, but not intradialytic exercise, increased AA removal throughout hemodialysis (9.8 ± 2.0, 10.2 ± 1.6, 16.7 ± 2.2, and 17.3 ± 2.3 g during PLA, PLA + EX, PRO, and PRO + EX interventions, respectively; protein effect P < 0.001, η2p = 0.97; exercise effect P = 0.32, η2p = 0.11). Protein ingestion increased plasma AA concentrations until the end of hemodialysis, whereas placebo ingestion resulted in decreased plasma AA concentrations (time effect P < 0.001, η2p > 0.84). Plasma AA availability (incremental AUC) was greater during PRO and PRO + EX interventions (49 ± 87 and 70 ± 34 mmol/L/240 min, respectively) compared with PLA and PLA + EX interventions (-227 ± 54 and -208 ± 68 mmol/L/240 min, respectively; protein effect P < 0.001, η2p = 0.98; exercise effect P = 0.21, η2p = 0.16).

CONCLUSIONS

Protein ingestion during hemodialysis compensates for AA removal and increases plasma AA availability both at rest and during recovery from intradialytic exercise. Intradialytic exercise does not compromise AA removal or reduce plasma AA availability during hemodialysis in a postabsorptive or postprandial state.

Estimation of Muscle Mass in the Integrated Assessment of Patients on Hemodialysis

Assessment of muscle mass (MM) or its proxies, lean tissue mass (LTM) or fat-free mass (FFM), is an integral part of the diagnosis of protein-energy wasting (PEW) and sarcopenia in patients on hemodialysis (HD). Both sarcopenia and PEW are related to a loss of functionality and also increased morbidity and mortality in this patient population. However, loss of MM is a part of a wider spectrum, including inflammation and fluid overload. As both sarcopenia and PEW are amendable to treatment, estimation of MM regularly is therefore of major clinical relevance. Whereas, computer-assisted tomography (CT) or dual-energy X-ray absorptiometry (DXA) is considered a reference method, it is unsuitable as a method for routine clinical monitoring. In this review, different bedside methods to estimate MM or its proxies in patients on HD will be discussed, with emphasis on biochemical methods, simplified creatinine index (SCI), bioimpedance spectroscopy (BIS), and muscle ultrasound (US). Body composition parameters of all methods are related to the outcome and appear relevant in clinical practice. The US is the only parameter by which muscle dimensions are measured. BIS and SCI are also dependent on either theoretical assumptions or the use of population-specific regression equations. Potential caveats of the methods are that SCI can be influenced by residual renal function, BIS can be influenced by fluid overload, although the latter may be circumvented by the use of a three-compartment model, and that muscle US reflects regional and not whole body MM. In conclusion, both SCI and BIS as well as muscle US are all valuable methods that can be applied for bedside nutritional assessment in patients on HD and appear suitable for routine follow-up. The choice for either method depends on local preferences. However, estimation of MM or its proxies should always be part of a multidimensional assessment of the patient followed by a personalized treatment strategy.

What Total Body Water Measurement Should Be Used for Prescribing the Dialysis Dose in Low-Flow Home Daily Dialysis?

INTRODUCTION

In low-flow home daily dialysis (HDD), the dialysis dose is evaluated from the total body water (TBW). TBW can be estimated by anthropometric methods or bioimpedance spectroscopy.

METHODS

A multicentric cross-sectional study of patients in HDD for >3 months was conducted to assess the correlation and the difference between the anthropometric estimate of TBW (Watson-TBW) and the bioimpedance estimate (BIS-TBW) and to analyse the impact on the dialysate volume prescribed.

RESULTS

Forty patients from 10 centres were included. The median BIS-TBW and Watson-TBW were 35.1 (29.1-41.4 L) and 36.9 (32-42.4 L), respectively. The 2 methods had a good correlation (r = 0.87, p < 0.05). However, Bland-Altman analysis showed an overestimation of TBW with Watson's formula, with a bias of 2.77 L. For 4, 5, or 6 sessions per week, the use of Watson-TBW increases the dialysate prescription per week by 100 L, 45 L, or 10 L, respectively, over our entire cohort. There is no increase in the volume of dialysate prescribed with the 7 sessions per week schedule.

CONCLUSION

BIS-TBW and Watson-TBW estimation have a good correlation; however, Watson's equation overestimates TBW. This overestimation is negligible for a prescription frequency of >5 sessions per week.

Novel equation for estimating resting energy expenditure in patients with chronic kidney disease

BACKGROUND

In chronic kidney disease (CKD), determining energy expenditure is the precondition for recommending energy intake in nutrition management.

OBJECTIVES

We aimed to develop and validate a resting energy expenditure (REE) equation for patients with CKD.

METHODS

This cross-sectional study enrolled 300 patients with CKD (stages 3-5) according to inclusion and exclusion criteria. Stepwise linear regression analysis was used to derive a new REE equation (eREE-CKD) according to actual REE (aREE) measured using indirect calorimetry in the development dataset. The eREE-CKD value was then validated with aREE in the validation dataset and compared with values from existing equations obtained in general populations, namely, the Harris-Benedict, Mifflin, WHO, and Schofield equations in terms of bias, precision, and accuracy.

RESULTS

The eREE-CKD equation: eREE-CKD (kcal) = (1 if male; 0 if female) × 106.0 - [1 if diabetes mellitus (DM); 0 if non-DM] × 51.6 - 4.7 × age (y) + 13.1 × weight (kg) + 645.5 (R2 = 0.779).The bias, precision, and accuracy (percentage of estimates that differed >20% from the measured REE) of the eREE-CKD equation were -0.4 (IQR: -29.8, 23.8) kcal, 98.4 (IQR: 79.5, 116.6) kcal, and 5.4%, respectively with indirect calorimetry as the reference method. Both bias and precision of the eREE-CKD were significantly better than the Harris-Benedict, WHO, and Schofield equations (P < 0.001) and similar to the Mifflin equation (P = 0.125 for bias and 0.268 for precision). Accuracy of the eREE-CKD was significantly better than the Harris-Benedict, WHO, Mifflin, and Schofield equations (P < 0.001). Bias, precision, and accuracy of the eREE-CKD equation were consistent when applied to subgroups categorized according to high-sensitivity C-reactive protein concentrations and CKD stages, respectively.

CONCLUSIONS

The eREE-CKD equation using age, sex, weight, and DM data could serve as a reliable tool for estimating REE in patients with CKD. This trial was registered at clinicaltrials.gov as NCT03377413.

Significance of Adipose Tissue Maintenance in Patients Undergoing Hemodialysis

In the general population, obesity is known to be associated with adverse outcomes, including mortality. In contrast, high body mass index (BMI) may provide a survival advantage for hemodialysis patients, which is known as the obesity paradox. Although BMI is the most commonly used measure for the assessment of obesity, it does not distinguish between fat and lean mass. Fat mass is considered to serve as an energy reserve against a catabolic condition, while the capacity to survive starvation is also thought to be dependent on its amount. Thus, fat mass is used as a nutritional marker. For example, improvement of nutritional status by nutritional intervention or initiation of hemodialysis is associated with an increase in fat mass. Several studies have shown that higher levels of fat mass were associated with better survival in hemodialysis patients. Based on body distribution, fat mass is classified into subcutaneous and visceral fat. Visceral fat is metabolically more active and associated with metabolic abnormalities and inflammation, and it is thus considered to be a risk factor for cardiovascular disease and mortality. On the other hand, subcutaneous fat has not been consistently linked to adverse phenomena and may reflect nutritional status as a type of energy storage. Visceral and subcutaneous adipose tissues have different metabolic and inflammatory characteristics and may have opposing influences on various outcomes, including mortality. Results showing an association between increased subcutaneous fat and better survival, along with other conditions, such as cancer or cirrhosis, in hemodialysis patients have been reported. This evidence suggests that fat mass distribution (i.e., visceral fat and subcutaneous fat) plays a more important role for these beneficial effects in hemodialysis patients.

Clinical and predictive value of simplified creatinine index used as muscle mass surrogate in end-stage kidney disease haemodialysis patients-results from the international MONitoring Dialysis Outcome initiative

Background

Protein-energy wasting, muscle mass (MM) loss and sarcopenia are highly prevalent and associated with poor outcome in haemodialysis (HD) patients. Monitoring of MM and/or muscle metabolism in HD patients is of paramount importance for timely detection of muscle loss and to intervene adequately. In this study we assessed the reliability and reproducibility of a simplified creatinine index (SCI) as a surrogate marker of MM and explored its predictive value on outcome.

Method

We included all in-centre HD patients from 16 European countries with at least one SCI. The baseline period was defined as 30 days before and after the first multifrequency bioimpedance spectroscopy measurement; the subsequent 7 years constituted the follow-up. SCI was calculated by the Canaud equation. Multivariate Cox proportional hazards models were applied to assess the association of SCI with all-cause mortality. Using backward analysis, we explored the trends of SCI before death. Bland–Altman analysis was performed to analyse the agreement between estimated and measured MM.

Results

We included 23 495 HD patients; 3662 were incident. Females and older patients have lower baseline SCI. Higher SCI was associated with a lower risk of mortality [hazard ratio 0.81 (95% confidence interval 0.79–0.82)]. SCI decline accelerated ∼5–7 months before death. Lean tissue index (LTI) estimated by SCI was correlated with measured LTI in both sexes (males: R² = 0.94; females: R² = 0.92; both P < 0.001). Bland–Altman analysis showed that measured LTI was 4.71 kg/m² (±2 SD: −12.54–3.12) lower than estimated LTI.

Conclusion

SCI is a simple, easily obtainable and clinically relevant surrogate marker of MM in HD patients.

Obesity, Chronic Kidney Disease, and Kidney Transplantation: An Evolving Relationship

Obesity has a fundamental role in driving the global kidney disease burden. The perplexing relationship of obesity with chronic kidney disease remains debated. However, a thorough understanding of the interplay of obesity in conjunction with chronic kidney disease and appropriate management options is lacking, leading to further increases in morbidity and mortality. Moreover, underutilization of bariatric procedures and unrealistic expectations of weight reduction based on body mass index, leading to poor access to kidney transplantation, are fueling the fire. In this review, we summarize the available data related to the obesity and chronic kidney disease association and its novel management options.

Seasonal variations in nutritional status and oxidative stress in patients on hemodialysis: Are they related?

OBJECTIVE

Seasonal variations in body composition and parameters that reflect nutritional status are well established in patients on hemodialysis (HD). However, to our knowledge, no study has assessed the changes in oxidative stress (OS). The aims of this study were to assess seasonal variations in OS, body composition, and other nutritional parameters.

METHODS

Seasonal variations in fat tissue mass (FTM), fat tissue index (FTI), adipose tissue mass (ATM), lean tissue mass (LTM), lean tissue index (LTI), body cell mass (BCM), overhydration (OH) volume, and OS (blood levels of derivatives of reactive oxygen metabolites [d-ROMs], thiobarbituric reactive substances, plasma protein reduced thiol content [THIOLS], and ferric reducing ability of plasma) were assessed in 45 patients on HD, 70 y of age (60.5-76.5 y).

RESULTS

FTM (P < 0.001), FTI (P < 0.001), and ATM (P < 0.001) significantly increased, whereas LTI (P < 0.001), LTM (P < 0.001), BCM (P < 0.001), and OH volume (P = 0.004) significantly decreased over the season. Additionally, significant seasonal variations in the levels of d-ROMs (P = 0.02) and THIOLS (P = 0.02) were found. Levels of d-ROMs were found to be a significant predictor of LTM and BCM (β = -0.57; 95% confidence interval [CI], -1.08 to -0.06; P = 0.03; β = -0.04; 95% CI, -0.075 to -0.006; P = 0.02). Furthermore, hip circumference was found to be the most significant predictor of the level of d-ROMs (β = 2.66; 95% CI; 0.28-5.04; P = 0.03) and waist-to-height ratio (β = 251; 95% CI, 16.6-477.2; P = 0.03) and serum prealbumin levels of THIOLS (β = 263; 95% CI, 6.8-521.1; P = 0.04).

CONCLUSION

These results suggest seasonal variations in OS in patients on HD and a possible interaction between OS and nutritional status in these patients.

Evolution of body composition following successful kidney transplantation is strongly influenced by physical activity: results of the CORPOS study

BACKGROUND

Weight gain (mainly gain of fat mass) occurs quickly after successful kidney transplantation and is associated with metabolic complications (alterations of glycaemic control, hyperlipidaemia). Determinants of weight gain are multifactorial and are mainly related to the transplant procedure itself (glucocorticoid use, increased appetite). In the modern era of transplantation, one challenge is to limit these metabolic alterations by promoting gain of muscle mass rather than fat mass. This prospective study was performed to assess determinants of fat mass, fat-free mass and body cell mass changes after kidney transplantation with a focus on physical activity and nutritional behaviour before and after transplantation.

METHODS

Patients were included at the time of listing for deceased donor kidney transplantation. Body composition was determined using dual X-ray absorptiometry and bioimpedance spectroscopy to assess fat mass, fat-free mass and body cell mass (= fat-free mass - extracellular water) at the time of inclusion, 12 months later, and 1, 6, 12 and 24 months after transplantation. Recall dietary data and physical activity level were also collected.

RESULTS

Eighty patients were included between 2007 and 2010. Sixty-five had a complete 24-month follow-up after kidney transplantation. Fat mass, fat-free mass and body cell mass decreased during the waiting period and early after kidney transplantation. The nadirs of body cell mass and fat-free mass occurred at 1 month and the nadir for fat mass occurred at 6 months. Maximum levels of all parameters of body composition were seen at 12 months, after which body cell mass and fat-free mass decreased, while fat mass remained stable. In multivariate analysis, male recipients, higher physical activity level and lower corticosteroid dose were significantly associated with better body cell mass recovery after kidney transplantation.

CONCLUSIONS

Lifestyle factors, such as physical activity level, together with low dose of corticosteroids seem to influence body composition evolution following kidney transplantation with recovery of body cell mass. Specific strategies to promote physical activity in kidney transplant recipients should be provided before and after kidney transplantation.

The Effects of Chronic Dialysis on Physical Status, Quality of Life, and Arterial Stiffness: A Longitudinal Study in Prevalent Dialysis Patients

INTRODUCTION

It is widely known that dialysis patients have significantly impaired functional outcomes and arterial stiffness, but still few studies have investigated the effects of dialysis longitudinally by a multidimensional approach. We aimed to assess longitudinal patterns of physical activity (PA), physical functioning (PF), health-related quality of life (HrQoL), body composition (BC), and arterial stiffness in prevalent dialysis patients.

MATERIALS AND METHODS

Thirty-nine prevalent dialysis patients (23 conventional hemodialysis [CHD] and 16 peritoneal dialysis) with a mean vintage of 25.7 (±22.1) months were included in this observational prospective study with a 2-year follow-up, and at baseline 20 healthy controls were included. Measurements were performed every 6 months. HrQoL was assessed using the Short Form-36 (SF-36) questionnaire. PA was assessed using the SenseWear™ Pro3 accelerometer. PF was assessed by walking speed, the PF subscale of the SF-36, and handgrip strength (HGS). BC was assessed using the Body Composition Monitor® and arterial stiffness by measuring carotid-femoral pulse wave velocity (PWV). The longitudinal trend was assessed using linear mixed models, correcting for sex, age, and dialysis vintage. For PWV, the trend was additionally corrected for diabetes and systolic blood pressure.

RESULTS

After correction, no statistically significant changes over time were observed for the parameters of PA, PF, HrQoL, and BC. In the combined group and in the group of CHD patients only, a significant change was observed for PWV (overall trend: p = 0.007 and p = 0.008, respectively). A statistically significant difference at baseline was observed between dialysis patients and healthy controls in all parameters, except for HGS and PWV.

DISCUSSION/CONCLUSION

We observed no statistically significant changes in functional outcomes during a 2-year follow-up period, but a significant increase was observed for arterial stiffness. These results might suggest that after a certain period in time, a relatively stable course is present in functional outcomes, but an ongoing deterioration in arterial stiffness occurs, which might increase the risk of cardiovascular disease and all-cause mortality in these patients.

Risk Factors for Muscle Loss in Hemodialysis Patients with High Comorbidity

With expanding kidney transplantation programs, remaining hemodialysis patients are more likely to have a high comorbidity burden and may therefore be more prone to lose muscle mass. Our aim was to analyze risk factors for muscle loss in hemodialysis patients with high comorbidity. Fifty-four chronic hemodialysis patients (Charlson Comorbidity Index 9.0 ± 3.4) were followed for 20 weeks using 4-weekly measurements of lean tissue mass, intracellular water, and body cell mass (proxies for muscle mass), handgrip strength (HGS), and biochemical parameters. Mixed models were used to analyze covariate effects on LTM. LTM (-6.4 kg, interquartile range [IQR] -8.1 to -4.8), HGS (-1.9 kg, IQR -3.1 to -0.7), intracellular water (-2.11 L, IQR -2.9 to -1.4) and body cell mass (-4.30 kg, IQR -5.9 to -2.9) decreased in all patients. Conversely, adipose tissue mass increased (4.5 kg, IQR 2.7 to 6.2), resulting in no significant change in body weight (-0.5 kg, IQR -1.0 to 0.1). Independent risk factors for LTM loss over time were male sex (-0.26 kg/week, 95% CI -0.33 to -0.19), C-reactive protein above median (-0.1 kg/week, 95% CI -0.2 to -0.001), and baseline lean tissue index ³10th percentile (-1.6 kg/week, 95% CI -2.1 to -1.0). Age, dialysis vintage, serum albumin, comorbidity index, and diabetes did not significantly affect LTM loss over time. In this cohort with high comorbidity, we found universal and prominent muscle loss, which was further accelerated by male sex and inflammation. Stable body weight may mask muscle loss because of concurrent fat gain. Our data emphasize the need to assess body composition in all hemodialysis patients and call for studies to analyze whether intervention with nutrition or exercise may curtail muscle loss in the most vulnerable hemodialysis patients.

Association between Ultrafiltration Rate and Clinical Outcome Is Modified by Muscle Mass in Hemodialysis Patients

BACKGROUND

The association between ultrafiltration rate (UFR) and mortality may be affected by the muscle mass or volume status in hemodialysis (HD) patients. However, there is an absence of data regarding this association.

METHODS

We performed an observational study on patients (≥18 years old) who had been on HD for at least 3 months. A body composition monitor (BCM) was used for baseline bioimpedance analysis measurement. The primary composite outcome was defined as the time to death or the first cardiovascular event.

RESULTS

The median (interquartile range) UFR, volume excess measured by the BCM, and lean tissue index (LTI) (calculated as lean tissue mass/height2) were 11.4 (8.0-15.0) mL/h/kg, 2.4 (1.4-4.1) L, and 12.5 (10.4-14.4) kg/m2, respectively. During 284 person-years of follow-up, the primary outcome occurred in 44 of the 167 patients (26%). Higher UFR was associated with an increased outcome of death or cardiovascular event; the adjusted hazard ratio (HR) was 1.044 (95% confidence interval [CI]: 1.006-1.083). This association remained consistent even after adjusting for volume excess. However, the association between UFR and the primary outcome was modified by LTI (pinteraction = 0.027); the association was significant in patients with LTI < 12.5 kg/m2, and the HR (95% CI) was 1.050 (1.001-1.102).

CONCLUSION

Higher UFR was associated with an increased risk of a composite outcome of death or cardiovascular event regardless of volume status in HD patients. However, muscle mass may modify the association between higher UFR and increased risk of a composite outcome.

Impact of old age on the association between in-center extended-hours hemodialysis and mortality in patients on incident hemodialysis

With the global problem of aging, it has become more difficult to improve the prognosis of older dialysis patients. Extended-hours hemodialysis offers longer treatment time compared to conventional hemodialysis regimen and provides favorable metabolic status, hemodynamic stability, and increased dietary intake. Despite prior studies reporting that in-center extended-hours hemodialysis can reduce the mortality rate, the treatment impact on elderly patients remains unclear. Therefore, we examined the association between extended-hours hemodialysis compared to conventional hemodialysis and all-cause mortality. Survival analyses using Cox proportional hazard model with multivariable adjustments and propensity-score based method were performed to compare mortality risk between 198 consecutive patients who started in-center extended-hours hemodialysis (Extended-HD) and 1407 consecutive patients who initiated conventional hemodialysis. The median age was 67.1 years in the Extended-HD group and 70.7 years in the conventional hemodialysis group. Extended-HD was associated with lower all-cause mortality in overall patients and the subgroup >70 years (adjusted hazard ratios of 0.60 [95% CI, 0.39–0.91] and 0.35 [95% CI, 0.18–0.69], respectively). There was a significant interaction between age >70 years and Extended-HD. In conclusion, extended-hours hemodialysis was associated with a lower mortality rate, especially in elderly patients.

Comparative Performance of Body Composition Parameters in Prediction of Death in Hospitalized Patients on Maintenance Hemodialysis: A Cohort Study

We compared the prognostic value of nutritional or volumetric parameters measured by body composition in hospitalized patients on maintenance hemodialysis. We conducted a cohort study to assess the association of different parameters of body composition with all-cause mortality in inpatients admitted to our nephrology department from January 2014 to December 2016. Of the 704 study patients, 160 (22.7%) died during a median follow-up of 33 months. In multivariate adjusted Cox models, higher ratio of extracellular water to body cell mass (ECW/BCM) (adjusted HR per 1-SD, 1.49; 95% CI, 1.19 to 1.85), lower lean tissue index (LTI) (adjusted HR per 1-SD, 0.70; 95% CI, 0.57 to 0.86) and lower body cell mass index (BCMI) (adjusted HR per 1-SD, 0.70; 95% CI, 0.58 to 0.85) were associated with a significantly greater risk of death. When these parameters were added to the fully adjusted model, BCMI performed best in improving the predictability for all-cause mortality (integrated discrimination improvement = 0.02, P = 0.04; net reclassification index = 0.11, P = 0.04). Among body composition indexes, ECW/BCM was the most relevant fluid volume indices to mortality and BCMI and LTI were the most relevant nutritional status indices to mortality in maintenance hemodialysis patients.

End-Stage Renal Disease Patients Lose a Substantial Amount of Amino Acids during Hemodialysis

BACKGROUND

Poor nutritional status is frequently observed in end-stage renal disease patients and associated with adverse clinical outcomes and increased mortality. Loss of amino acids (AAs) during hemodialysis (HD) may contribute to protein malnutrition in these patients.

OBJECTIVE

We aimed to assess the extent of AA loss during HD in end-stage renal disease patients consuming their habitual diet.

METHODS

Ten anuric chronic HD patients (mean ± SD age: 67.9 ± 19.3 y, BMI: 23.2 ± 3.5 kg/m2), undergoing HD 3 times per week, were selected to participate in this study. Spent dialysate was collected continuously and plasma samples were obtained directly before and after a single HD session in each participant. AA profiles in spent dialysate and in pre-HD and post-HD plasma were measured through ultra-performance liquid chromatography to determine AA concentrations and, as such, net loss of AAs. In addition, dietary intake before and throughout HD was assessed using a 24-h food recall questionnaire during HD. Paired-sample t tests were conducted to compare pre-HD and post-HD plasma AA concentrations.

RESULTS

During an HD session, 11.95 ± 0.69 g AAs were lost via the dialysate, of which 8.26 ± 0.46 g were nonessential AAs, 3.69 ± 0.31 g were essential AAs, and 1.64 ± 0.17 g were branched-chain AAs. As a consequence, plasma total and essential AA concentrations declined significantly from 2.88 ± 0.15 and 0.80 ± 0.05 mmol/L to 2.27 ± 0.11 and 0.66 ± 0.05 mmol/L, respectively (P < 0.05). AA profiles of pre-HD plasma and spent dialysate were similar. Moreover, AA concentrations in pre-HD plasma and spent dialysate were strongly correlated (Spearman's ρ = 0.92, P < 0.001).

CONCLUSIONS

During a single HD session, ∼12 g AAs are lost into the dialysate, causing a significant decline in plasma AA concentrations. AA loss during HD can contribute substantially to protein malnutrition in end-stage renal disease patients. This study was registered at the Netherlands Trial Registry (NTR7101).

Three compartment bioimpedance spectroscopy in the nutritional assessment and the outcome of patients with advanced or end stage kidney disease: What have we learned so far?

Bioimpedance spectroscopy (BIS) is an easily applicable tool to assess body composition. The three compartment model BIS (3C BIS) conventionally expresses body composition as lean tissue index (LTI) (lean tissue mass [LTM]/height in meters squared) and fat tissue index (FTI) (adipose tissue mass/height in meters squared), and a virtual compartment reflecting fluid overload (FO). It has been studied extensively in relation to diagnosis and treatment guidance of fluid status disorders in patients with advanced‐stage or end‐stage renal disease. It is the aim of this article to provide a narrative review on the relevance of 3C BIS in the nutritional assessment in this population. At a population level, LTI decreases after the start of hemodialysis, whereas FTI increases. LTI below the 10th percentile is a consistent predictor of outcome whereas a low FTI is predominantly associated with outcome when combined with a low LTI. Recent research also showed the connection between low LTI, inflammation, and FO, which are cumulatively associated with an increased mortality risk. However, studies toward nutritional interventions based on BIS data are still lacking in this population. In conclusion, 3C BIS, by disentangling the components of body mass index, has contributed to our understanding of the relevance of abnormalities in different body compartments in chronic kidney disease patients, and appears to be a valuable prognostic tool, at least at a population level. Studies assessing the effect of BIS guided nutritional intervention could further support its use in the daily clinical care for renal patients.

Dietary Protein and Physical Activity Interventions to Support Muscle Maintenance in End-Stage Renal Disease Patients on Hemodialysis

End-stage renal disease patients have insufficient renal clearance capacity left to adequately excrete metabolic waste products. Hemodialysis (HD) is often employed to partially replace renal clearance in these patients. However, skeletal muscle mass and strength start to decline at an accelerated rate after initiation of chronic HD therapy. An essential anabolic stimulus to allow muscle maintenance is dietary protein ingestion. Chronic HD patients generally fail to achieve recommended protein intake levels, in particular on dialysis days. Besides a low protein intake on dialysis days, the protein equivalent of a meal is extracted from the circulation during HD. Apart from protein ingestion, physical activity is essential to allow muscle maintenance. Unfortunately, most chronic HD patients have a sedentary lifestyle. Yet, physical activity and nutritional interventions to support muscle maintenance are generally not implemented in routine patient care. To support muscle maintenance in chronic HD patients, quantity and timing of protein intake should be optimized, in particular throughout dialysis days. Furthermore, implementing physical activity either during or between HD sessions may improve the muscle protein synthetic response to protein ingestion. A well-orchestrated combination of physical activity and nutritional interventions will be instrumental to preserve muscle mass in chronic HD patients.

Effects of intradialytic aerobic exercise on hemodialysis patients: a systematic review and meta-analysis

OBJECTIVE

Intradialytic exercise (IDE) is not yet a routine practice for hemodialysis patients, the lack of guidelines supporting it being a major reason. This systematic review and meta-analysis of aerobic IDE interventions examined the efficacy of IDE regarding quality of life (QOL), serum phosphorus, dialysis efficiency, inflammatory status, vitamin D3, parathyroid hormone, intake of phosphate binders, mortality and hospitalization rate.

METHODS

Pubmed, Medline (Ovid), Embase (Ovid), Cochrane, and Cinahl (EBSCO) databases were searched to retrieve studies up to June 12, 2018. A manual reference search was also performed. Studies were included if they evaluated (a) aerobic IDE effect on at least one of our study parameters, (b) adult hemodialysis patients, (c) patients for > 1 month.

RESULTS

Twenty-two studies were retrieved (706 participants), of which 12 were eligible for meta-analysis. Aerobic IDE had a significant positive effect on the QOL physical component score (QOL-PSC) and on mental component score (QOL-MCS) of SF36, but not on serum phosphorus or Kt/V.

CONCLUSIONS

IDE incorporation into clinical practice has a significant positive effect on QOL-PSC and QOL-MCS. In the reviewed studies, IDE did not result in any health hazard in hemodialysis patients. Nevertheless, future research should assess the long-term effectiveness and safety of IDE. The limitations of this review include the lack of quality analysis of the studies, the limited number of studies that could be included in the meta-analysis, the diversity in the exercise intensity, duration and modality, and the limited data for several outcomes.

PROSPERO REGISTRATION ID

CRD42016052062.

Low lean tissue mass can be a predictor of one-year survival in hemodialysis patients

Purpose: Nutritional status has a significant impact on the outcomes in the dialysis population. The aim of this study was to evaluate the association between body composition and a one-year survival of hemodialysis patients.

Methods: Forty-eight patients with chronic kidney disease stage V treated with hemodialysis for more than three months were included. Body composition was assessed by bioimpedance spectroscopy (Body Composition Monitor, Fresenius Medical Care). Blood samples for serum creatinine, serum albumin, serum prealbumin, high sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), insulin-like growth factor 1(IGF-1) concentrations were taken before the midweek dialysis session.

Results: Over the course of a one-year observation, seven patients died. We observed a significantly lower lean tissue index (LTI) (p = .013) and higher IL-6 (p = .032) and hsCRP levels (p = .011) among the patients who died. The remaining biochemical markers did not differ between these two groups. Kapplan–Meier analysis revealed a worse survival rate in patients with sarcopenia (lower than the 10th percentile for their age and gender) in comparison with those with normal LTI. However, it was not of statistical significance (p = .055). LTI inversely correlated with age and IL-6 and positively with IGF-1.

Conclusions: Sarcopenia defined as decreased LTI, is a relatively common condition among patients undergoing maintenance hemodialysis, it can also be associated with a lower one-year survival rate. Decreased lean tissue mass can be associated with old age, lower IGF-1 levels and higher IL-6 levels. Body composition assessment may provide prognostic data for hemodialysis patients.

Sex-age-specific handgrip strength and mortality in an incident hemodialysis cohort: The risk explained by nutrition and comorbidities

OBJECTIVE:

To investigate associations of sex-age-specific handgrip strength by a dynamometer with all-cause mortality and the percent excess risk explained (%ERE) by comorbidities and nutritional indicators in incident maintenance hemodialysis patients.

METHODS:

Prospective cohort of 413 adult patients (165 women, 248 men, 299 <60 years and 114 ⩾60 years) with <6 months (82% <3 months) on dialysis enrolled in PROHEMO in Salvador, Brazil. Low and high handgrip strength groups were based on sex-age-specific cutoffs (17.8 kg for women <60 years, 13.8 kg for women ⩾60 years, 29.5 kg for men <60 years, and 21.9 kg for men ⩾60 years). We used Cox regression to estimate the mortality hazard ratio. The %ERE was determined by the equation (HR1 - HR2)/(HR1 - 1) × 100, in which HR1 represented the hazard ratio in a model with a smaller number of covariates and HR2 represented the hazard ratio in a subsequent model with the inclusion of new covariates plus the variables included in the previous model.

RESULTS:

The mortality hazard ratio comparing low and high handgrip strength was 2.58 (95% confidence interval: 1.73, 3.85) in the model with sociodemographic factors and vintage and 2.25 (95% confidence interval: 1.49, 3.43) with addition of comorbidities, corresponding to a %ERE of 21%. The hazard ratio was 1.98 (95% confidence interval: 1.29, 3.06) after addition of nutritional indicators corresponding to %ERE of 38%. Results stratified by age and gender followed similar patterns.

CONCLUSION:

These results provide support for the assessment of handgrip strength in all maintenance hemodialysis patients for early identification of those who may require special care to improve nutritional status and survival.

Relation of Lean Body Mass and Muscle Performance to Serum Creatinine Concentration in Hemodialysis Patients

INTRODUCTION

Serum creatinine concentration is an important uremic marker and predictor of survival in dialysis patients. This cross-sectional case-control study was made to quantitatively describe the relation between lean body mass (LBM), physical performance measures, and serum creatinine values.

METHODS

Ninety hemodialysis patients and 106 controls were measured by bioimpedance spectroscopy, handgrip strength, sit-to-stand test, and biochemical serum tests. Univariate and multivariate general linear models were used to analyze quantitative relations.

RESULTS

At univariate regression LBM accounted for 13.6% variability of serum creatinine concentration. In adjusted analyses with age, height, and body mass, LBM persisted as the only significant predictor of midweek predialysis serum creatinine concentration. Physical performance measures handgrip strength and sit-to-stand performance did not improve prediction of serum creatinine. With addition of serum urea concentration and residual diuresis the predictive value of the regression model improved to account for 45% of serum creatinine variability. Each kg of LBM was associated with 7.7 μmol/l increase in creatinine concentration (95% CI 3.4-12.1, p=0.001).

CONCLUSION

Bioimpedance derived LBM has a significant linear relation with predialysis serum creatinine concentrations. Hereby described quantitative relation should help clinicians to better evaluate observed creatinine concentrations of hemodialysis patients when bioimpedance derived LBM is available.

Haemodialysis patients with diabetes eat less than those without: A plea for a permissive diet

AIM

The main cause of malnutrition in haemodialysis patients is a spontaneous decline in energy and protein intakes. This study aims to report the dietary energy intake (DEI), dietary protein intake (DPI), and dietary micronutrient intake in a French HD population, to report factors associated with a low DPI and DEI, and to analyze if nutritional intake was correlated with nutritional status.

METHODS

We conducted an observational cross-sectional study in a haemodialysis population of 87 adult patients in July 2014. Daily nutritional oral intake, handgrip strength, body composition measured by bioimpedancemetry, and biological and dialysis parameters were obtained from medical records. Statistical analyses of parameters associated with DEI and DPI were performed.

RESULTS

The median age (interquartile range) of the population was 77.3 [71.1; 84.8] years, 57.5% were men, and 52.9% had diabetes mellitus. Median weight-adjusted DEI was 18.4 [15.7;22.3] kcal/kg per day (1308 [1078; 1569] kcal/day), and median weight-adjusted DPI was 0.80 [0.66; 0.96] g/kg per day (57.5 [47.1; 66.8] g/day). In multivariate analysis, weight-adjusted DEI was statistically lower in patients with diabetes (coefficient [95%CI] -3.81[-5.21;-2.41] kcal/kg per day; P = 0.01) but was not associated with the others parameters. When DEI was not adjusted for weight, diabetes was no longer associated with DEI, but female gender (-178[-259;-961] kcal/day; P = 0.03) and a higher Charlson comorbidity index (-30[-44;-15]; P = 0.04) were associated with a lower calorie intake. Results for DPI were similar except that the Charlson comorbidity index did not reach significance.

CONCLUSIONS

Diabetes is an important factor associated with low dietary intake in haemodialysis patients. Restrictive regimens should be prescribed cautiously in haemodialysis patients, especially in those with diabetes.

Bioimpedance Spectroscopy as a Practical Tool for the Early Detection and Prevention of Protein-Energy Wasting in Hemodialysis Patients

OBJECTIVES

To evaluate whether body composition monitor (BCM) could be a practical instrument for nephrologists to assess nutritional status in patients on hemodialysis (HD) and whether it is more effective in identifying patients at highest risk of developing protein-energy wasting (PEW) alone or in combination with other tools currently used for that purpose.

DESIGN

Observational cross-sectional study in 91 HD patients (60 ± 14 years, 70.3% male, 24 ± 4.1 kg/m² body mass index) from 2 different locations.

METHODS

Nutritional status was evaluated by anthropometric methods (biceps and triceps skinfold thickness, waist circumference, and arm muscular circumference), biochemical nutritional markers, malnutrition-inflammation score (MIS), and BCM. The patients were grouped into those with and without PEW by using classical criteria and then classified as being adequately or inadequately nourished according to a BCM flow chart to detect those requiring preferential nutritional intervention. A multivariate approach was used to calculate the risk of developing PEW.

RESULTS

Anthropometric measurements revealed significantly lower body mass index (<23 kg/m²; odds ratios [OR] = 13.3 and P = 0.001) and arm muscular circumference < p10 (OR = 34, P < 0.001) in the PEW group. MIS was above 5 in all the patients classified as having PEW. BCM showed that fat tissue index < p10 was significantly lower in this group (OR = 1.52), and a decision tree using the lean tissue index < p10, fat tissue index < p10, and extracellular water > 15% revealed that 42.9% of the patients would need nutritional monitoring. On multivariate analysis, insufficient nutritional status detected by BCM decision tree was an independent prognostic factor for developing PEW. About 9.89% of the patients were classified as PEW, with MIS > 5, and insufficient nutritional status detected by BCM required preferential nutritional intervention.

CONCLUSION

BCM is a practical instrument for nephrologists to assess nutritional status in patients on HD and is useful for the early prevention and detection of PEW, as is able to identify differences in body composition, predict clinically important outcomes, and classify patients requiring preferential nutritional intervention.

Prevalence and Risk of Protein-Energy Wasting Assessed by Subjective Global Assessment in Older Adults With Advanced Chronic Kidney Disease: Results From the EQUAL Study

OBJECTIVES

Prevalence and risk factors for protein-energy wasting (PEW) are poorly studied in the nondialysis, older population with advanced chronic kidney disease (CKD). Our aim was to evaluate the prevalence of PEW in advanced stage CKD patients aged greater than 65 years. Furthermore, we aimed to describe risk factors for PEW in the overall study population and among obese individuals.

DESIGN

Prospective observational cohort study.

METHODS

The EQUAL study, a European Quality Study on treatment in advanced chronic kidney disease, is a multicenter prospective observational cohort study in six European countries. We included patients aged ≥65 years with incident glomerular filtration rate <20mL/min/1.73m² not on dialysis attending nephrology care. PEW was assessed by 7-point Subjective Global Assessment (7-p SGA).

RESULTS

In general, the study cohort (n = 1,334) was overweight (mean body mass index [BMI] 28.4 kg/m²). The majority of the patients had a normal nutritional status (SGA 6-7), 26% had moderate PEW (SGA 3-5), and less than 1% had severe PEW (SGA 1-2). Muscle wasting and loss of fat tissue were the most frequent alterations according to the SGA subscales, especially in those aged >80 years. The prevalence of PEW was higher among women, increased with age, and was higher in those with depression/dementia. PEW was the most common in those with underweight (BMI <22 kg/m²), 55% or normal weight (BMI 22-25 kg/m²), 40%. In obese individuals (BMI >30 kg/m²), 25% were diagnosed with protein wasting. Risk factors for SGA ≤5 in obese people were similar to those for the overall study population.

CONCLUSION

This European multicenter study shows that the prevalence of PEW is high in patients with advanced CKD aged >65 years. The risk of PEW increases substantially with age and is commonly characterized by muscle wasting. Our study suggests that focus on nutrition should start early in the follow-up of older adults with CKD.

Inflammation and premature aging in advanced chronic kidney disease

Systemic inflammation in end-stage renal disease is an established risk factor for mortality and a catalyst for other complications, which are related to a premature aging phenotype, including muscle wasting, vascular calcification, and other forms of premature vascular disease, depression, osteoporosis, and frailty. Uremic inflammation is also mechanistically related to mechanisms involved in the aging process, such as telomere shortening, mitochondrial dysfunction, and altered nutrient sensing, which can have a direct effect on cellular and tissue function. In addition to uremia-specific causes, such as abnormalities in the phosphate-Klotho axis, there are remarkable similarities between the pathophysiology of uremic inflammation and so-called "inflammaging" in the general population. Potentially relevant, but still somewhat unexplored in this respect, are abnormal or misplaced protein structures, as well as abnormalities in tissue homeostasis, which evoke danger signals through damage-associated molecular patterns, as well as the senescence-associated secretory phenotype. Systemic inflammation, in combination with the loss of kidney function, can impair the resilience of the body to external and internal stressors by reduced functional and structural tissue reserves, and by impairing normal organ crosstalk, thus providing an explanation for the greatly increased risk of homeostatic breakdown in this population. In this review, the relationship between uremic inflammation and a premature aging phenotype, as well as potential causes and consequences, are discussed.

Physical Activity in End-Stage Renal Disease Patients: The Effects of Starting Dialysis in the First 6 Months after the Transition Period

OBJECTIVES

Physical inactivity in end-stage renal disease (ESRD) patients is associated with increased mortality, and might be related to abnormalities in body composition (BC) and physical performance. It is uncertain to what extent starting dialysis influences the effects of ESRD on physical activity (PA). This study aimed to compare PA and physical performance between stage 5 chronic kidney disease (CKD-5) non-dialysis and dialysis patients, and healthy controls, to assess alterations in PA during the transition from CKD-5 non-dialysis to dialysis, and to relate PA to BC.

METHODS

For the cross-sectional analyses 44 CKD-5 non-dialysis patients, 29 dialysis patients, and 20 healthy controls were included. PA was measured by the SenseWear™ pro3. Also, the walking speed and handgrip strength (HGS) were measured. BC was measured by the Body Composition Monitor©. Longitudinally, these parameters were assessed in 42 CKD-5 non-dialysis patients (who were also part of the cross-sectional analysis), before the start of dialysis and 6 months thereafter.

RESULTS

PA was significantly lower in CKD-5 non-dialysis patients as compared to that in healthy controls but not as compared to that in dialysis patients. HGS was significantly lower in dialysis patients as compared to that in healthy controls. Walking speed was significantly lower in CKD-5 non-dialysis patients as compared to that in healthy controls but not as compared to that in dialysis patients. Six months after starting dialysis, activity related energy expenditure (AEE) and walking speed significantly increased.

CONCLUSIONS

PA is already lower in CKD-5 non-dialysis patients as compared to that in healthy controls and does not differ from that of dialysis patients. However, the transition phase from CKD-5 non-dialysis to dialysis is associated only with a modest improvement in AEE.

Changes in Body Composition in the Two Years after Initiation of Haemodialysis: A Retrospective Cohort Study

Malnutrition is common in haemodialysis (HD) and is linked to poor outcomes. This study aimed to describe changes in body composition after the initiation of HD and investigate whether any routinely collected parameters were associated with these changes. The study cohort came from the HD population of a single centre between 2009 and 2014. Body composition measurements were obtained from a database of bioimpedance results using the Body Composition Monitor (BCM), while demographics and laboratory values came from the renal unit database. Primary outcomes were changes in normohydration weight, lean tissue mass and adipose tissue mass over the two years after HD initiation. A total of 299 patients were included in the primary analyses, showing an increase in adipose tissue, loss of lean tissue and no significant change in normohydration weight. None of the routinely collected parameters were associated with the lean tissue changes. Loss of lean tissue over the first year of dialysis was associated with increased mortality. The results showing loss of lean tissue that is not limited to those traditionally assumed to be at high risk supports interventions to maintain or improve lean tissue as soon as possible after the initiation of HD. It highlights the importance of monitoring nutrition and the potential for routine use of bioimpedance.

Hidden Obesity in Dialysis Patients: Clinical Implications

While body-mass index (BMI) is used to diagnose obesity in the general population, its application in the end-stage renal disease (ESRD) population is fraught with difficulty. A major limitation is its inability to distinguish muscle mass from fat mass, thereby leading to misclassification of individuals with poor muscle mass but excess adipose tissue as non-obese (i.e. BMI <30 kg/m(2) ). As muscle wasting is common among ESRD patients, this is an important problem. A substantial proportion of ESRD patients have levels of BMI in the normal range, yet excess adiposity based on other measures. The importance of this "hidden" obesity remains to be determined, but it must be recognized in order for obesity interventions to be appropriately targeted and tested in the ESRD population.