ESPEN practical guideline on clinical nutrition in hospitalized patients with acute or chronic kidney disease

BACKGROUND AND AIMS

Hospitalized patients often have acute kidney disease (AKD) or chronic kidney disease (CKD), with important metabolic and nutritional consequences. Moreover, in case kidney replacement therapy (KRT) is started, the possible impact on nutritional requirements cannot be neglected. On this regard, the present guideline aims to provide evidence-based recommendations for clinical nutrition in hospitalized patients with KD.

METHODS

The standard operating procedure for ESPEN guidelines was used. Clinical questions were defined in both the PICO format, and organized in subtopics when needed, and in non-PICO questions for the more general topics. The literature search was from January 1st, 1999 until January 1st, 2020. Each question led to one or more recommendation/statement and related commentaries. Existing evidence was graded, as well as recommendations and statements were developed and agreed upon in a multistage consensus process.

RESULTS

The present guideline provides 32 evidence-based recommendations and 8 statements, defining how to assess nutritional status, how to define patients at risk, how to choose the route of feeding, and how to integrate nutrition with KRT. In the final online voting, a strong consensus was reached in 84% at least of recommendations and 100% of statements.

CONCLUSION

The presence of KD in hospitalized patients identifies a highly heterogeneous group of subjects with widely varying nutrient needs and intakes. Considering the high nutritional risk related with this clinical condition, an individualized approach consisting of nutritional status evaluation and monitoring, frequent evaluation of nutritional requirements, and careful integration with KRT should be planned to avoid both underfeeding and overfeeding. Practical recommendations and statements were developed, aiming at defining suggestions for everyday clinical practice in the individualization of nutritional support in this patient setting. Literature areas with scarce or without evidence were also identified, thus requiring further basic or clinical research.

The expected changes with different periods of home-based resistance exercise in patients with chronic kidney disease

BACKGROUND

The comprehensive impact of prolonged home-based resistance training on individuals grappling with chronic kidney disease (CKD) have yet to be fully elucidated. This study aimed to explore the outcomes of varying exercise durations on physical performance, nutritional status, and kidney function within this specific population, encompassing patients undergoing dialysis and those affected by severe sarcopenia.

METHODS

This was a 1-year observational double cohort study following a 52-week longitudinal design, we enrolled 101 adult CKD outpatients. These participants were divided into two groups: the continuous group, comprising individuals who consistently exercised for over 6 months, and the interrupted group, which included those who did not sustain regular exercise for the same duration. The exercise regimen involved resistance exercises conducted at least 3 to 5 days per week, involving activities like lifting dumbbells and executing weighted wall squats. Physical activity assessments and biochemical blood tests were conducted at weeks 0, 4, 16, 28, 40, and 52 for all participants.

RESULTS

The continuous exercise group exhibited better handgrip strength and sit-to-stand movement compared to the interrupted group. Their estimated glomerular filtration rate stayed steady while the interrupted group was declined. Additionally, those who exercised consistently had better metabolism: higher carbon dioxide levels, increased albumin, better nutritional scores, and lower levels of blood urea nitrogen, creatinine, fasting blood glucose, and body weight. Subsequent adjustments for potential confounding factors continued to show improved physical performance and kidney function over time.

CONCLUSION

Our findings indicate the advantageous impact of extended resistance exercise training on overall health of CKD patients, even those on dialysis or with severe sarcopenia. Dedication to this exercise routine could improve kidney function, metabolism, and physical abilities in these patients.

Making the invisible visible: imaging techniques for assessing muscle mass and muscle quality in chronic kidney disease

Muscle wasting and low muscle mass are prominent features of protein energy wasting (PEW), sarcopenia and sarcopenic obesity in patients with chronic kidney disease (CKD). In addition, muscle wasting is associated with low muscle strength, impaired muscle function and adverse clinical outcomes such as low quality of life, hospitalizations and increased mortality. While assessment of muscle mass is well justified, the assessment of skeletal muscle should go beyond quantity. Imaging techniques provide the means for non-invasive, comprehensive, in-depth assessment of the quality of the muscle such as the infiltration of ectopic fat. These techniques include computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound. Dual energy X-ray absorptiometry is also an imaging technique, but one that only provides quantitative and not qualitative data on muscle. The main advantage of imaging techniques compared with other methods such as bioelectrical impedance analysis and anthropometry is that they offer higher precision and accuracy. On the other hand, the higher cost for acquiring and maintaining the imaging equipment, especially CT and MRI, makes these less-used options and available mostly for research purposes. In the field of CKD and end-stage kidney disease (ESKD), imaging techniques are gaining attention for evaluating muscle quantity and more recently muscle fat infiltration. This review describes the potential of these techniques in CKD and ESKD settings for muscle assessment beyond that of muscle quantity.

Association between sarcopenic obesity and mortality in patients on peritoneal dialysis: a prospective cohort study

Background

Whether sarcopenic obesity had unfavorable effect on survival of peritoneal dialysis (PD) patients is unknown. We aimed to investigate the association between sarcopenic obesity and survival in PD patients.

Methods

This was a prospective observational study. Eligible PD patients from November 2016 to December 2017 were enrolled and followed until August 31, 2023. Sarcopenia was defined following the recommendations of the Asian Working Group for Sarcopenia (AWGS) as low appendicular skeletal muscle mass index (ASMI) and handgrip strength (HGS). Obesity was defined using the percentage of body fat (PBF). Survival analysis was conducted using the Kaplan-Meier and log-rank test. The Cox regression and the cumulative incidence competing risk (CICR) analyzes were used to investigate the association between sarcopenic obesity and all-cause mortality.

Results

A total of 223 patients were enrolled with 133 (59.6%) males, a median age of 57.5 (44.6, 65.7) years, a median dialysis vintage of 20.3 (6.4, 57.7) months and 48 (21.5%) who had comorbid diabetes mellitus. Among them, 46 (20.6%) patients were sarcopenic, and 25 (11.2%) patients were diagnosed with sarcopenic obesity. After followed up for 51.6 (25.6, 73.9) months, the Kaplan-Meier curve showed the sarcopenic obesity (log-rank = 13.527, p < 0.001) group had significant lower survival rate compared to the nonsarcopenic non-obesity group. For multivariate analysis, the CICR method showed patients with sarcopenic obesity had significantly higher mortality rate (HR: 2.190, 95% CI: 1.011-4.743, p = 0.047) compared to those with nonsarcopenic non-obesity.

Conclusion

Sarcopenia is not uncommon in PD patients, with a considerable proportion having sarcopenic obesity. There is a significant association between sarcopenic obesity and an increased risk of mortality in PD patients.

Sarcopenic obesity and its relation with muscle quality and mortality in patients on chronic hemodialysis

BACKGROUND & AIMS

Sarcopenia is prevalent in patients with end-stage kidney disease (ESKD) on hemodialysis (HD), and is associated with poor outcomes, while obesity may be protective. Sarcopenic obesity is associated with increased frailty, morbidity and mortality in the general population. Myosteatosis, i.e., muscle fat infiltration, has major effects on muscle strength and physical performance, but is poorly investigated in the nephrology setting. In the present study we aimed to assess the association between sarcopenic obesity, as diagnosed by abdominal CT, and mortality. Moreover, the relationship between myosteatosis, sarcopenic obesity and mortality was also investigated.

METHODS

This is a retrospective study in which ESKD patients on HD submitted to unenhanced abdominal CT for clinical reasons at least 6 months after dialysis initiation were evaluated for sarcopenic obesity and myosteatosis, defined as intermuscular fat area and low attenuation muscle area. Sarcopenic obesity was diagnosed in cases of low abdominal skeletal muscle area and high total fat area. Receiver-operating characteristics (ROC) analysis with Youden index was used to determine the cut-off for high total fat area. Intermuscular fat area and low attenuation muscle area were evaluated by applying the Hounsfield unit of interest (-190; -30, and -29; +29 respectively). Cox regression analysis was used to evaluate the association between predictors and mortality risk.

RESULTS

We enrolled 212 patients, aged 68.8 (±14.7) years, 65.5% (139/212) male. Median follow-up was 19.7 (interquartile range [IQR] 2.7-35) months. Sarcopenic obesity was diagnosed in 19.8% of patients and was associated with increased mortality (HR: 3.29 (1.72; 6.27), P < 0.001), and with the presence of myosteatosis. Both intermuscular fat area and low attenuation muscle area were associated with increased mortality in adjusted analyses.

CONCLUSIONS

Patients with sarcopenic obesity have increased myosteatosis. Sarcopenic obesity and myosteatosis are associated with increased mortality in patients on HD.

Associations of body mass index (BMI) and BMI change with progression of chronic kidney disease in children

BACKGROUND

Obesity is prevalent among children with chronic kidney disease (CKD) and is associated with cardiovascular disease and reduced quality of life. Its relationship with pediatric CKD progression has not been described.

METHODS

We evaluated relationships between both body mass index (BMI) category (normal, overweight, obese) and BMI z-score (BMIz) change on CKD progression among participants of the Chronic Kidney Disease in Children study. Kaplan-Meier survival curves and multivariable parametric failure time models depict the association of baseline BMI category on time to kidney replacement therapy (KRT). Additionally, the annualized percentage change in estimated glomerular filtration rate (eGFR) was modeled against concurrent change in BMIz using multivariable linear regression with generalized estimating equations which allowed for quantification of the effect of BMIz change on annualized eGFR change.

RESULTS

Participants had median age of 10.9 years [IQR: 6.5, 14.6], median eGFR of 50 ml/1.73 m2 [IQR: 37, 64] and 63% were male. 160 (27%) of 600 children with non-glomerular and 77 (31%) of 247 children with glomerular CKD progressed to KRT over a median of 5 years [IQR: 2, 8]. Times to KRT were not significantly associated with baseline BMI category. Children with non-glomerular CKD who were obese experienced significant improvement in eGFR (+ 0.62%; 95% CI: + 0.17%, + 1.08%) for every 0.1 standard deviation concurrent decrease in BMI. In participants with glomerular CKD who were obese, BMIz change was not significantly associated with annualized eGFR change.

CONCLUSION

Obesity may represent a target of intervention to improve kidney function in children with non-glomerular CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Normal weight and waist obesity indicated by increased total body fat associated with all-cause mortality in stage 3–5 chronic kidney disease

Patients with chronic kidney disease (CKD) demonstrate a survival benefit with a high body mass index (BMI); this is the obesity paradox. Central obesity has a higher prognostic value than BMI, even in those with normal weight. Whether total body fat percentage (TBF%) provides more information than BMI and waist circumference (WC) remains unknown. We included 3,262 Asian patients with stage 3–5 CKD and divided these patients by TBF% and waist-to-height ratio (WHtR) quartiles (Q1–Q4). TBF% was associated with BMI, WC, nutritional markers, and C-reactive protein. In all patients, BMI but not TBF% or WHtR demonstrated a survival paradox. In patients with BMI &lt;25 kg/m2, but not in those with BMI ≥ 25 kg/m2, TBF% Q4 and WHtR Q4 were associated with all-cause mortality, with hazard ratios [HRs; 95% confidence intervals (CIs)] of 2.35 (1.31–4.22) and 1.38 (1.06–1.80), respectively. The HRs of TBF% Q4 for all-cause mortality were 2.90 (1.50–5.58) in patients with a normal WC and 3.81 (1.93–7.50) in patients with normal weight and normal WC (All P for interaction &lt; 0.05). In conclusion, TBF% can predict all-cause mortality in patients with advanced CKD and a normal weight, normal WC, or both.

Obesity Management in Kidney Transplant Candidates: Current Paradigms and Gaps in Knowledge

In this review, we discuss the increasing prevalence of obesity among people with chronic and end-stage kidney disease (ESKD) and implications for kidney transplant (KT) candidate selection and management. Although people with obesity and ESKD receive survival and quality-of-life benefits from KT, most KT programs maintain strict body mass index (BMI) cutoffs to determine transplant eligibility. However, BMI does not distinguish between visceral adiposity, which confers higher cardiovascular risks and risks of perioperative and adverse posttransplant outcomes, and muscle mass, which is protective in ESKD. Furthermore, requirements for patients with obesity to lose weight before KT should be balanced with the findings of numerous studies that show weight loss is a risk factor for death among patients with ESKD, independent of starting BMI. Data suggest that KT is associated with survival benefits relative to remaining on dialysis for candidates with obesity although recipients without obesity have higher delayed graft function rates and longer transplant hospitalization durations. Research is needed to determine the optimal body composition metrics for KT candidacy assessments and risk stratification. In addition, ESKD-specific obesity management guidelines are needed that will address the neurologic, behavioral, socioeconomic, and physical underpinnings of this increasingly common disease.

Significant Association of Diabetes With Mortality of Chronic Hemodialysis Patients, Independent of the Presence of Obesity, Sarcopenia, and Sarcopenic Obesity

OBJECTIVES

This retrospective cohort study investigated the association of diabetes with mortality in hemodialysis patients with regard to obesity, sarcopenia, and sarcopenic obesity, along with examining the prevalence of each group and diabetes.

METHODS

Muscle strength, muscle mass, and fat mass were evaluated using a hand dynamometer and dual-energy X-ray absorptiometry, respectively, in 308 chronic hemodialysis patients (age 58.0 ± 11.9 years, hemodialysis duration 6.5 ± 6.0 years, males 60.1%, diabetes 32.8%). Sarcopenia was defined according to the new criteria established by the Asian Working Group on Sarcopenia 2019. Obesity was defined by percent body fat mass (males ≥25%, females ≥35%).

RESULTS

The enrolled patients were divided into the normal (38.7%), obesity (18.8%), sarcopenia (26.9%), and sarcopenic obesity (15.6%) groups. The prevalence of diabetes was significantly skewed among the 4 groups (χ² test, P = .0057), being higher in the sarcopenic obesity group (54.2%) compared to the others (25.9-33.7%). Multivariate regression analysis revealed that diabetes was significantly and independently associated with sarcopenic obesity (odds ratio 3.495, 95% confidence interval 1.683-7.255, P = .0008) after adjustments for several cofounders, but not significantly associated with sarcopenia. During the follow-up period of 76 ± 35 months, 100 patients died. Those in the sarcopenia and sarcopenic obesity groups had significantly higher rates of all-cause mortality compared to patients in the normal and obesity groups (P = .0004, log-rank test). Furthermore, multivariate Cox proportional hazards analysis revealed that presence of diabetes was significantly associated with higher all-cause mortality in all 308 patients, after adjustments for several factors, including the presence of each group in 4 models.

CONCLUSION

Sarcopenic obesity is highly prevalent in chronic hemodialysis patients. Diabetes was found to be a significant and independent contributor to the presence of sarcopenic obesity. Diabetes was shown to be a significant predictor of all-cause mortality, independent of the present normal, obesity, sarcopenia, and sarcopenic obesity groups.

ESPEN guideline on clinical nutrition in hospitalized patients with acute or chronic kidney disease

Acute kidney disease (AKD) - which includes acute kidney injury (AKI) - and chronic kidney disease (CKD) are highly prevalent among hospitalized patients, including those in nephrology and medicine wards, surgical wards, and intensive care units (ICU), and they have important metabolic and nutritional consequences. Moreover, in case kidney replacement therapy (KRT) is started, whatever is the modality used, the possible impact on nutritional profiles, substrate balance, and nutritional treatment processes cannot be neglected. The present guideline is aimed at providing evidence-based recommendations for clinical nutrition in hospitalized patients with AKD and CKD. Due to the significant heterogeneity of this patient population as well as the paucity of high-quality evidence data, the present guideline is to be intended as a basic framework of both evidence and - in most cases - expert opinions, aggregated in a structured consensus process, in order to update the two previous ESPEN Guidelines on Enteral (2006) and Parenteral (2009) Nutrition in Adult Renal Failure. Nutritional care for patients with stable CKD (i.e., controlled protein content diets/low protein diets with or without amino acid/ketoanalogue integration in outpatients up to CKD stages four and five), nutrition in kidney transplantation, and pediatric kidney disease will not be addressed in the present guideline.

Sarcopenia in chronic kidney disease: what have we learned so far?

The term sarcopenia was first introduced in 1988 by Irwin Rosenberg to define a condition of muscle loss that occurs in the elderly. Since then, a broader definition comprising not only loss of muscle mass, but also loss of muscle strength and low physical performance due to ageing or other conditions, was developed and published in consensus papers from geriatric societies. Sarcopenia was proposed to be diagnosed based on operational criteria using two components of muscle abnormalities, low muscle mass and low muscle function. This brought awareness of an important nutritional derangement with adverse outcomes for the overall health. In parallel, many studies in patients with chronic kidney disease (CKD) have shown that sarcopenia is a prevalent condition, mainly among patients with end stage kidney disease (ESKD) on hemodialysis (HD). In CKD, sarcopenia is not necessarily age-related as it occurs as a result of the accelerated protein catabolism from the disease and from the dialysis procedure per se combined with low energy and protein intakes. Observational studies showed that sarcopenia and especially low muscle strength is associated with worse clinical outcomes, including worse quality of life (QoL) and higher hospitalization and mortality rates. This review aims to discuss the differences in conceptual definition of sarcopenia in the elderly and in CKD, as well as to describe etiology of sarcopenia, prevalence, outcome, and interventions that attempted to reverse the loss of muscle mass, strength and mobility in CKD and ESKD patients.

Lower Leg Fat Depots Are Associated with Albuminuria Independently of Obesity, Insulin Resistance, and Metabolic Syndrome (Korea National Health and Nutrition Examination Surveys 2008 to 2011)

BACKGROUND

Although the involvement of obesity in metabolic disorders is well known, leg fat depot influences on albuminuria have not been determined.

METHODS

This population-based, cross-sectional study used a nationally representative sample of 2,076 subjects aged ≥20 years from the Korea National Health and Nutrition Examination Surveys of 2008 to 2011. The ratio of leg fat to total fat (LF/TF ratio) was assessed by dual X-ray absorptiometry, and albuminuria was defined as more than one positive dipstick test or an albumin-to-creatinine ratio of ≥30 mg/g.

RESULTS

Individuals whose LF/TF ratio was in the lowest tertile showed a higher proportion of albuminuria than those in the highest tertile (odds ratio [OR], 2.82; 95% confidence interval [CI], 2.01 to 3.96; P<0.001). This association was observed in both sexes, all age groups, and all subgroups stratified by body mass index, waist circumference, homeostasis model assessments of insulin resistance, and the presence of metabolic syndrome (all, P<0.05). Multiple logistic regression analyses also demonstrated that the lowest LF/TF ratio was independently associated with albuminuria risk (OR, 1.55 to 2.16; all, P<0.05). In addition, the risk of albuminuria was higher in sarcopenic individuals with lower LF/TF ratios than in the highest LF/TF ratio subjects without sarcopenia (OR, 3.73; 95% CI, 2.26 to 6.13).

CONCLUSION

A lower LF/TF ratio was associated with an increased risk of albuminuria independent of obesity, insulin resistance, and metabolic syndrome, and when combined with sarcopenia, the albuminuria risk synergistically increased. Hence, our findings may have implications to improve risk stratification and recommendations on body fat distribution in the general population.

The obesity paradox: A further consideration in dialysis patients

Several epidemiological cohorts have demonstrated that higher body mass index (BMI) is associated with lower mortality risk among patients receiving hemodialysis. However, BMI may be an inaccurate indicator of nutritional status among dialysis patients because it does not differentiate between muscle and fat mass or provide information about body fat distribution. More sophisticated methods of body composition analysis are therefore required to address the question of which component is associated with greater survival. Recent evidence has also shown that changes in body weight and body composition are more strongly associated with mortality in dialysis patients than measurement of BMI at a single time point. Given that obesity is common among the dialysis population, weight loss interventions are encouraged for obese dialysis patients who are on a transplant waiting list in order to increase the access for transplantation.

Prevalence of dynapenic obesity and sarcopenic obesity and their associations with cardiovascular disease risk factors in peritoneal dialysis patients

Background

Dynapenic obesity and sarcopenic obesity increase cardiovascular disease (CVD) and mortality in nonuremic patients. The present study was designed to determine the prevalence of dynapenic obesity and sarcopenic obesity and their associations with CVD risk factors in peritoneal dialysis (PD) patients.

Methods

All eligible PD patients in Tehran peritoneal dialysis centers were included in this cross-sectional study. Skeletal muscle mass and fat mass were assessed using bioelectrical impedance analysis. Muscle strength and physical performance were determined using hand grip strength and a 4-meter walk gait speed test, respectively. In addition, a 5-mL blood sample was obtained from each patient.

Results

The prevalence of dynapenic obesity and sarcopenic obesity were 11.4% and 3.8% in PD patients, respectively. Serum high-sensitive C-reactive protein (hs-CRP), soluble intercellular adhesion molecule type 1, triglyceride, total cholesterol, and low-density lipoprotein cholesterol were significantly higher in PD patients with dynapenic obesity than in dynapenic nonobese and nondynapenic nonobese patients. Similarly, serum concentrations of CVD risk factors in PD patients with sarcopenic obesity were higher than in nonsarcopenic nonobese patients, but these differences were statistically significant only for serum hs-CRP and triglyceride. In addition, muscle strength and skeletal muscle mass percentage were negatively associated with markers of inflammation and dyslipidemia, whereas body fat percentage was positively associated with these CVD risk factors.

Conclusion

This study indicates that although the prevalence of dynapenic obesity and sarcopenic obesity are relatively low in PD patients, these disorders may be associated with CVD risk factors.

Risk of hospitalization associated with body mass index and weight changes among prevalent haemodialysis patients

The impact of body mass index (BMI) and body weight on hospitalization rates in haemodialysis patients is unknown. This study hypothesizes that being either underweight or obese is associated with a higher hospitalization rate. Observational study of 6296 European haemodialysis patients with prospective data collection and follow-up every six months for three years (COSMOS study). The risk of being hospitalized was estimated by a time-dependent Cox regression model and the annual risk (incidence rate ratios, IRR) by Poisson regression. We considered weight loss, weight gain and stable weight. Weight change analyses were also performed after patient stratification according to their baseline BMI. A total of 3096 patients were hospitalized at least once with 9731 hospitalizations in total. The hospitalization incidence (fully adjusted IRR 1.28, 95% CI [1.18-1.39]) was higher among underweight patients (BMI <20kg/m²) than patients of normal weight (BMI 20-25kg/m²), while the incidence of overweight (0.88 [0.83-0.93]) and obese patients (≥30kg/m², 0.85 [0.79-0.92]) was lower. Weight gain was associated with a reduced risk of hospitalization. Conversely, weight loss was associated with a higher hospitalization rate, particularly in underweight patients (IRR 2.85 [2.33-3.47]). Underweight haemodialysis patients were at increased risk of hospitalization, while overweight and obese patients were less likely to be hospitalized. Short-term weight loss in underweight individuals was associated with a strikingly high hospitalization rate.

Impact of Misclassification of Obesity by Body Mass Index on Mortality in Patients With CKD

Introduction

Unlike the general population, a higher body mass index (BMI) is associated with greater survival among patients with chronic kidney disease (CKD). This “obesity paradox” may be due to limitations of BMI as a measure of adiposity in CKD. Both BMI and body fat percentage (BF%) are used to classify obesity, but outcomes may vary. Therefore, we investigated the 2 different cutoffs for diagnosing obesity (BMI ≥28 kg/m² or BF% >25% for men and >35% for women) and the impact on all-cause mortality in CKD.

Methods

A total of 326 patients with non–dialysis-dependent CKD were prospectively followed for a median of 4.9 years (range 2.9–5.3). BF% and lean body mass were determined using the Body Composition Monitor, a novel multifrequency bioimpedance spectroscopy device. Covariates included age, gender, diabetes, cardiovascular disease, estimated glomerular filtration rate, proteinuria, and high-sensitivity C-reactive protein.

Results

Per the BMI definition, 27.9% of patients were obese. However, 48.8% of patients were obese according to the BF% definition. A BMI ≥28 kg/m² had a moderately high specificity of 83.2% but a low sensitivity of 39.6% for detecting BF%-defined obesity. In the fully adjusted models containing both BMI and BF%, obesity defined by BMI was associated with a significantly lower risk of death (hazard ratio [HR]: 0.23; 95% CI: 0.07–0.71; P = 0.011), whereas the result was reversed when obesity was defined by BF% (HR: 2.75; 95% CI: 1.28–5.89; P = 0.009). When patients were classified into 4 distinct groups based on both the BMI and BF% cutoffs for obesity, a considerable proportion of patients (29.4%) had excess body fat in the context of a normal BMI. These patients were more likely to have lower lean body mass (i.e., sarcopenic obesity) and had higher mortality compared with patients with obesity defined by both BMI and BF% (HR: 5.11; 95% CI: 1.43–18.26; P = 0.012).

Conclusion

Diagnostic discordance between BMI and BF% may partly explain the obesity paradox. Proper diagnosis of obesity in patients with CKD is required for both risk prediction and treatment.

Visceral Adipose Tissue and Leptin Hyperproduction Are Associated With Hypogonadism in Men With Chronic Kidney Disease

OBJECTIVE

Hypogonadism is a common endocrine disorder in men with chronic kidney disease (CKD), but its pathophysiology is poorly understood. We here explore the plausible contribution of abdominal adiposity and leptin hyperproduction to testosterone deficiency in this patient population.

DESIGN

Cross-sectional analysis with all men included the Malnutrition, Inflammation and Vascular Calcification cohort, which enrolled consecutive nondialyzed patients with CKD stages 3-5.

SUBJECTS

A total of 172 men with CKD stages 3-5 nondialysis (median age 61 [45-75] years, median glomerular filtration rate 24 [9-45] mL/min/1.73 m²). In them, serum levels of total testosterone, estrogen, sex hormone binding globulin, and leptin were quantified, together with visceral adipose tissue (VAT) by thoracic and abdominal CT scan.

INTERVENTION

None, observational study.

MAIN OUTCOME MEASURE

Total testosterone, hypogonadism.

RESULTS

The median level of total testosterone was 11.7 (7.3-18.4) nmol/L, with hypogonadism (<10 nmol/L) present in 52 (30%) patients. Testosterone-deficient patients presented with significantly higher body mass index, waist circumference, and VAT. An inverse correlation between testosterone and VAT (rho = -0.25, P = .001) or waist circumference (rho = -0.20, P = .008) was found, also after multivariate adjustment including sex hormone binding globulin and estrogen. Total testosterone was inversely correlated with serum leptin (rho = -0.22, P = .003), and the ratio of leptin/VAT, an index of leptin hyperproduction, was strongly and independently associated with the prevalence of hypogonadism in multivariable regression analyses.

CONCLUSION

Visceral adiposity independently associated with lower testosterone levels among men with CKD stage 3-5 nondialysis. The observed link between hyperleptinemia and hypogonadism is in line with previous evidence on direct effects of leptin on testosterone production.

Characterization of deficits across the spectrum of motor abilities in dialysis patients and the impact of sarcopenic overweight and obesity

BACKGROUND & AIMS

Physical performance deficits in kidney failure predict mortality and quality of life. We aimed to quantify deficits in multiple motor abilities, investigate associations of lean and fat tissue content with test results and analyzed performance of sarcopenic individuals with adipose tissue excess.

METHODS

Ninety hemodialysis patients and 140 healthy controls performed 6-minute walk test, gait speed measurement, sit-to-stand and time up and go tests, upper extremity handgrip and tapping tests, Stork balance and forward bend flexibility tests. Human Activity Profile questionnaire was used to assess habitual activity. Body composition was measured by bioimpedance analysis.

RESULTS

Relative performance deficit of dialysis patients in age, sex, height and comorbidity adjusted estimated marginal means was largest for balance and flexibility (-52 and -33%), followed by lower extremity deficits in sit-to-stand, time up and go and 6-minute walk tests (-29, -19 and -15%, respectively), p < 0.05 for all comparisons. Upper extremity performance was less affected. Lean tissue index associated significantly positively with five and fat tissue index associated significantly negatively with two out of nine tests. Sarcopenic overweight and obese individuals exhibited significant deficits mainly in lower extremity tests with worse composite lower extremity score when compared to other categories of body composition.

CONCLUSIONS

Patients with hemodialysis treated kidney failure have largest functional deficits in balance, flexibility and lower extremity functions. Lean and fat mass associate oppositely with physical performance measures and individuals at unfavorable extremes of these indices express significantly impaired lower extremity functions.

Sensitivity and Specificity of Body Mass Index as a Marker of Obesity in Elderly Patients on Hemodialysis

OBJECTIVES

Diagnosing obesity by body mass index (BMI) may not be reliable in elderly individuals due to the changes in body composition. We aimed to analyze the accuracy of BMI thresholds by World Health Organization (WHO) and Nutrition Screening Initiative (NSI) to diagnose obesity in elderly patients on hemodialysis (HD).

DESIGN

Multicenter cross-sectional study.

SETTING

Six dialysis facilities.

SUBJECTS

169 elderly on chronic HD (70.4 ± 7.1 years; 63.9% men).

MAIN OUTCOME VARIABLE

Total body fat percentage (BF%) was assessed by the sum of skinfold thicknesses and abdominal fat by waist circumference (WC). Both were used as reference to test the specificity and sensitivity of BMI thresholds (WHO: ≥30 kg/m(2); NSI: >27 kg/m(2)).

RESULTS

The prevalence of obesity according to NSI-BMI, WHO-BMI, BF%, and WC thresholds were 31%, 13%, 27%, and 29.6% in men, respectively, and 36%, 15%, 13%, and 75% in women. Compared to BF%, the sensitivity of NSI-BMI was moderate (65.5%) for men and high (100%) for women, whereas that of WHO-BMI was low (31%) for men and high (87.5%) for women. Compared with WC, NSI-BMI had good (75%) sensitivity for men and moderate (47.8%) for women, whereas WHO-BMI had moderate (43.8%) sensitivity for men and low (19.6%) for women. The best agreement with BF% was observed for NSI-BMI in men (kappa = 0.46) and for WHO-BMI in women (kappa = 0.80). For WC, the best agreement was for WHO-BMI for men (kappa = 0.63) and NSI-BMI for women (kappa = 0.31).

CONCLUSIONS

BMI thresholds do not accurately diagnose adiposity in elderly on HD. Therefore, using BMI may lead to misclassifications in this segment population.

Body Fat Analysis in Predialysis Chronic Kidney Disease: Multifrequency Bioimpedance Assay and Anthropometry Compared With Dual-Energy X-Ray Absorptiometry

OBJECTIVES

Body composition analysis is required for accurate assessment of nutritional status in patients with predialysis chronic kidney disease (CKD). The reference method for assessing body fat is dual-energy X-ray absorptiometry (DXA), but it is relatively expensive and often not available for widespread clinical use. There is only limited data on the utility of less expensive and easily available alternatives such as multifrequency bioimpedance assay (BIA) and skinfold thickness (SFT) measurements for assessing body fat in predialysis CKD. The study intends to assess the utility of BIA and SFT in measuring body fat compared to the reference method DXA in subjects with predialysis CKD.

METHODS

Body composition analysis was done in 50 subjects with predialysis CKD using multifrequency BIA, SFT, and DXA. The agreement between the body fat percentages measured by reference method DXA and BIA/SFT was assessed by paired t-test, intraclass correlation coefficients (ICCs), regression, and Bland-Altman plots.

RESULTS

Percentage of body fat measured by BIA was higher compared to the measurements by DXA, but the difference was not significant (30.44 ± 9.34 vs. 28.62 ± 9.00; P = .071). The ICC between DXA and BIA was 0.822 (confidence interval: 0.688, 0.899; P = .000). The mean values of body fat percentages measured by anthropometry (SFT) was considerably lower when compared to DXA (23.62 ± 8.18 vs. 28.62 ± 9.00; P = .000). The ICC between DXA and SFT was .851 (confidence interval: 0.739, 0.915; P = .000). Bland-Altman plots showed that BIA overestimated body fat by a mean of 1.8% (standard deviation, 6.98), whereas SFT underestimated body fat by 5% (standard deviation, 4.01). Regression plots showed a better agreement between SFT and DXA (R(2) = .79) than BIA (R(2) = .50). Overall, SFT showed better agreement with the DXA. Body mass index (BMI) showed a moderate positive correlation with body fat measured by DXA whereas serum albumin failed to show good correlation.

CONCLUSIONS

SFT showed relatively better agreement with the reference method DXA, compared to BIA. SFT can be used as a tool for assessing nutritional status in predialysis patients with CKD.

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.

Body composition in chronic kidney disease

PURPOSE OF REVIEW

To summarize the latest information on body composition among patients with chronic kidney disease and its association with outcomes.

RECENT FINDINGS

Obesity is increasing among patients with end-stage renal disease and is more prevalent when direct measures of adiposity are used rather than BMI. High BMI is not associated with better survival among patients with earlier chronic kidney disease or after kidney transplantation, suggesting that excess fat is most protective among the sickest patients. Despite the positive association between BMI and survival among patients with end-stage renal disease, visceral fat is associated with coronary artery calcification and adverse cardiovascular events. Muscle wasting is prominent among patients with chronic kidney disease, sometimes even in the setting of obesity. Obesity and muscle wasting are associated with worse physical functioning. Indicators of low muscle size and strength are associated with higher mortality. Some interventions can affect body composition, but whether they affect survival has not been determined.

SUMMARY

Recent studies show that a high BMI is not protective for all patients with chronic kidney disease and is associated with poor physical functioning and frailty. Visceral adiposity is associated with adverse cardiovascular outcomes. Sarcopenia is common among patients with end-stage renal disease and is associated with worse physical performance and higher mortality.

Nutritional Status of Maintenance Dialysis Patients: Low Lean Body Mass Index and Obesity Are Common, Protein-Energy Wasting Is Uncommon

BACKGROUND AND AIMS

Maintenance dialysis patients are at increased risk of abnormal nutritional status due to numerous causative factors, both nutritional and non-nutritional. The present study assessed the current prevalence of protein-energy wasting, low lean body mass index and obesity in maintenance dialysis patients, and compared different methods of nutritional assessment.

METHODS

In a cross-sectional study conducted in 2014 at Roskilde Hospital, Denmark, we performed anthropometry (body weight, skinfolds, mid-arm, waist, and hip circumferences), and determined plasma albumin and normalized protein catabolic rate in order to assess the prevalence of protein-energy wasting, low lean body mass index and obesity in these patients.

RESULTS

Seventy-nine eligible maintenance dialysis patients participated. The prevalence of protein-energy wasted patients was 4% (95% CI: 2-12) as assessed by the coexistence of low lean body mass index and low fat mass index. Low lean body mass index was seen in 32% (95% CI: 22-44). Obesity prevalence as assessed from fat mass index was 43% (95% CI: 32-55). Coexistence of low lean body mass index and obesity was seen in 10% (95% CI: 5-19). The prevalence of protein-energy wasting and obesity varied considerably, depending on nutritional assessment methodology.

CONCLUSIONS

Our data indicate that protein-energy wasting is uncommon, whereas low lean body mass index and obesity are frequent conditions among patients in maintenance dialysis. A focus on how to increase and preserve lean body mass in dialysis patients is suggested in the future. In order to clearly distinguish between shortage, sufficiency and abundance of protein and/or fat deposits in maintenance dialysis patients, we suggest the simple measurements of lean body mass index and fat mass index.