Factors Associated with Decreased Lean Tissue Index in Patients with Chronic Kidney Disease

The Association between Iron Deficiency and Renal Outcomes Is Modified by Sex and Anemia in Patients with Chronic Kidney Disease Stage 1–4

Iron deficiency is prevalent in women and patients with chronic kidney disease (CKD). Iron deficiency is not only related to anemia but contributes to adverse consequences for the kidney as well. Whether iron status is associated with renal outcomes after considering sex and anemia in patients with CKD stage 1–4 is unclear. Thus, we investigated the association of iron or iron saturation with renal outcomes in a CKD cohort. During a follow-up of 8.2 years, 781 (31.2%) patients met the composite renal outcome of renal replacement therapy and a 50% decline in renal function. In linear regression, iron was associated with sex, hemoglobin (Hb), and nutritional markers. In a fully adjusted Cox regression model, the male patients with normal iron had a significantly decreased risk of renal outcomes (hazard ratio (HR) 0.718; 95% confidence interval (CI) 0.579 to 0.889), but the female patients did not exhibit this association. The non-anemic patients (Hb ≥ 11 g/dL) had a decreased risk of renal outcomes (HR 0.715; 95% CI 0.568 to 0.898), but the anemic patients did not. In the sensitivity analysis, transferrin saturation (TSAT) showed similar results. When comparing iron and TSAT, both indicators showed similar prognostic values. In conclusion, iron deficiency, indicated by either iron or iron saturation, was associated with poor renal outcomes in the male or non-anemic patients with CKD stage 1–4.

Established risk prediction models for the incidence of a low lean tissue index in patients with peritoneal dialysis

Objective

The objective of this study is to investigate the incidence of low lean tissue index (LTI) and the risk factors for low LTI in peritoneal dialysis (PD) patients, including to establish risk prediction models.

Methods

A total of 104 PD patients were enrolled from October 2019 to 2021. LTI was measured by bioimpedance spectroscopy. Multivariate logistic regression and machine learning were used to analyze the risk factors for low LTI in PD patients. Kaplan–Meier analysis was used to analyze the survival rate of patients with low LTI.

Results

The interleukin-6 (IL-6) level, red cell distribution width (RDW), overhydration, body mass index (BMI), and the subjective global assessment (SGA) rating significantly differed between the low LTI and normal LTI groups (all p < 0.05). Multivariate logistic regression showed that IL-6 (1.10 [95% CI: 1.02–1.18]), RDW (1.87 [95% CI: 1.18–2.97]), BMI (0.97 [95% CI: 0.68–0.91]), and the SGA rating (6.33 [95% CI: 1.59–25.30]) were independent risk factors for LTI. Cox regression analysis showed that low LTI (HR 3.14, [95% CI: 1.12–8.80]) was the only significant risk factor for all-cause death in peritoneal dialysis patients. The decision process to predict the incidence of low LTI in PD patients was established by machine learning, and the area under the curve of internal validation was 0.6349.

Conclusions

Low LTI is closely related to mortality in PD patients. Microinflammatory status, high RDW, low BMI and low SGA rating are risk factors for low LTI in PD patients. The developed prediction model may serve as a useful tool for assessing low LTI in PD patients.

Nutrition-related diseases and cardiovascular mortality in American society: national health and nutrition examination study, 1999-2006

Background

Despite many significant advances in treatment and management, cardiovascular disease remains the main cause of the global disease burden. Nutrition-related disease is a modifiable cardiovascular risk factor. However, few studies have examined the relationship between nutrition-related diseases and cardiovascular mortality.

Objective

We aimed to investigate the association of nutrition-related diseases with cardiovascular mortality based on a large nationally representative community population.

Design

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) 1999–2006 with mortality follow-up through December 31, 2015. Finally, 12,469 participants were analyzed. Each participant was assigned to one of four groups: normal nutrition without sarcopenia, sarcopenia with normal nutrition, malnutrition without sarcopenia, and malnutrition-sarcopenia syndrome. Survival curves and Cox regressions based on the NHANES recommended weights were used to assess the association between nutrition-related diseases and cardiovascular mortality.

Results

Of the 12,469 patients included in the study and divided into four groups, malnutrition-sarcopenia syndrome had the highest 5- and 10-year cardiovascular mortality rates. After adjustment for related factors, sarcopenia with normal nutrition (hazard ratio [HR]: 1.62, 95% confidence interval [CI]: 1.28–2.06; P < 0.001), malnutrition without sarcopenia (HR: 1.28, 95% CI:1.03–1.58; P = 0.024), and malnutrition-sarcopenia syndrome (HR: 2.66, 95% CI:1.89 − 3.74; P < 0.001) were significantly associated with increased risk of all-cause mortality. Malnutrition-sarcopenia syndrome remained associated with an increased risk of cardiovascular mortality (HR: 3.56, 95% CI: 1.17 − 10.84; P < 0.001).

Conclusions

Malnutrition-sarcopenia syndrome was highly prevalent among community-dwelling adults in the United States and was a strong prognostic factor for cardiovascular mortality in the community setting. Randomized clinical trials are needed to demonstrate whether prevention or treatment of malnutrition-sarcopenia syndrome in community populations can reduce global cardiovascular mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14257-8.

Correlations among lean tissue index, physical activity, clinical parameters, diet quality, and nutritional status in patients receiving haemodialyses

INTRODUCTION

Poor diet quality and malnutrition accelerate protein and energy depletion. This can result in a diminished lean tissue index (LTI) and an inability to perform daily activities, both of which increase the risk of falls and affect the quality of life.

OBJECTIVE

This study investigated the correlations among LTI, physical activity (PA), clinical parameters, diet quality, and nutritional status.

METHODS

A cross-sectional study design was employed. Participants in stable conditions receiving haemodialyses were enroled. LTI was measured using a body composition monitor. Three-day dietary records and demographic and clinical parameters were collected.

RESULTS

In total, 104 patients receiving haemodialyses were recruited (53.8% men, aged 57.7 ± 11.78 years; dialysis duration, 7.3 ± 6.04 years). LTI was not associated with diet quality; LTI was positively correlated with sex and negatively correlated with age, dialysis duration, and fat tissue index (FTI); and lean tissue index was positively correlated with PA. Among patients with a normal LTI, the odds ratio for low-FTI was 31.04 times higher than that for high-FTI. In total, 80.8% of the participants had poor diet quality, which was mainly attributed to their excessive intake of saturated fatty acids and insufficient fruit intake.

CONCLUSIONS

Although diet quality was unrelated to the LTI, the results indicated that most patients receiving haemodialyses had poor diet quality. Therefore, this topic merits further investigation.

Impact of frailty and its inter-relationship with lean tissue wasting and malnutrition on kidney transplant waitlist candidacy and delisting

BACKGROUND & AIMS

Frailty and body composition contribute to adverse pre-transplant outcomes including hospitalization and waitlist mortality, but the interaction between frailty and body composition remains uncertain.

METHODS

Frailty was diagnosed by Clinical Frailty Scale (CFS) and a standard Frailty Questionnaire (FQ). Nutrition was evaluated by serum albumin level, subjective global assessment (SGA) and comprehensive malnutrition-inflammation score (MIS). Body composition was assessed by bioimpedance spectroscopy. All patients were followed up for three years. Primary outcome measure was a composite of death and permanent removal from waitlist. Secondary outcomes were emergency room attendance and hospitalization.

RESULTS

432 prevalent peritoneal dialysis (PD) patients were recruited. 148 (34.3%) were listed on transplant waitlist. Frailty, age and comorbidity load predicted waitlisting. With time, 47 patients were delisted. Frailty by FQ (p = 0.028), serum albumin level (p = 0.005) and waist circumference (p = 0.010) predicted delisting after adjustment for confounders. Frailty significantly interacted with lean tissue wasting (FQ: p = 0.002, CFS: p = 0.048), and MIS (FQ: p = 0.004; CFS: p = 0.014) on delisting. Lean tissue wasting caused 2.56 times risk of delisting among frail individuals identified by FQ (p = 0.016), while serum albumin and the presence of diabetes mellitus predicted the risk of delisting among non-frail individuals. Lean tissue wasted and frail subjects had a higher all-cause and infection-related hospitalization.

CONCLUSION

Frailty predicted both kidney transplant waitlisting and subsequent delisting. Frailty interacted with body composition on transplant waitlist delisting. Lean tissue wasting and malnutrition independently predicted delisting in frail and non-frail listed subjects respectively.

Prevalence and Factors Associated with Sarcopenia in Patients on Maintenance Dialysis in Australia-A Single Centre, Cross-Sectional Study

Background: Sarcopenia is associated with significant morbidity and mortality in patients with chronic kidney disease. The prevalence of sarcopenia in the dialysis population varies from 4% to 63%. However, the prevalence and risk factors of sarcopenia in the Australian dialysis population remain uncertain. Aim: To study the prevalence of sarcopenia in patients on maintenance dialysis by using the European Working Group on Sarcopenia in Older People (EWGSOP) diagnostic criteria of sarcopenia and to identify associated risk factors. Methods: We evaluated adult patients on maintenance haemodialysis and peritoneal dialysis in this single-centre cross-sectional study in Australia. Patient’s clinical (age, gender, dialysis modality and diabetic status) and laboratory parameters (serum albumin, calcium, phosphate, 25-hydroxy-vitamin D and parathyroid hormone levels) were investigated. We employed bioimpedance spectroscopy, hand grip dynamometer and the timed up and go test (TUG) to evaluate muscle mass, strength and function, respectively. Results: We evaluated 39 dialysis patients with a median age of 69 years old. The prevalence of sarcopenia was 18%. Sarcopenia was associated with low serum albumin (p = 0.02) and low serum phosphate level (p = 0.04). Increasing age and female sex were potential risk factors for sarcopenia (p = 0.05 and 0.08, respectively). Low lean muscle mass, reduced hand grip strength and prolonged TUG were present in 23.1%, 41% and 40.5%, respectively, of the cohort. The hand grip test had good correlation with lean muscle evaluation and the TUG. Conclusions: Sarcopenia was prevalent in 18% of maintenance haemodialysis patients from an Australian single-centre cohort, with low serum albumin and phosphate as significant risk factors.

The Effects of Oral Energy-Dense Supplements on Nutritional Status in Nondiabetic Maintenance Hemodialysis Patients: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Fat-based energy-dense nutritional supplements may offer benefits over protein- or carbohydrate-dense supplements for patients receiving dialysis because of the adverse metabolic consequences of the latter. We conducted a randomized controlled trial to assess the effects of the short-term use of a fat-based nutritional supplement on various measures of nutritional status in patients receiving maintenance hemodialysis who have low dietary energy intake.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We enrolled nondiabetic patients receiving hemodialysis for >3 months who had inadequate dietary energy intake (<30 kcal/kg per day). The participants were randomly assigned in a 1:1 ratio to receive an oral fat-based energy-dense supplement (300 kcal daily) or routine care for 12 weeks (n=120 per group). The primary outcome was the change in phase angle measured by bioelectrical impedance analysis, a marker of cell integrity and body cell mass, from the baseline to week 12. The secondary outcomes were changes in quality of life. Other outcomes included laboratory nutritional indicators and physical examinations.

RESULTS

The average age of the total population was 47 (SD: 12) years, and 55% were men. The median of dialysis vintage was 43.4 (22.5-76.3) months; 240 participants were randomly assigned to the intervention (n=120) or control group (n=120). In total, 228 (95%) participants completed the trial. The change in phase angle did not differ significantly between the intervention and control groups (estimate, 0.0; 95% confidence interval, -0.1 to 0.1 versus estimate, 0.0; 95% confidence interval, -0.1 to 0.1; estimated difference, 0.0; 95% confidence interval -0.2 to 0.2; P=0.99). None of the 19 domains of quality of life differed between the groups. Adverse events were reported in 23 (19%) participants in the control group and 40 (33%) participants in the intervention group.

CONCLUSIONS

In nondiabetic patients on maintenance hemodialysis, short-term administration of fat-based energy-dense nutritional supplement has no clinically significant effect on nutritional status as measured by phase angle.

PODCAST

This article contains a podcast at https://https://www.asn-online.org/media/podcast/CJASN/2021_08_03_CJN16821020.mp3.

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.

Resistance exercise training ameliorates chronic kidney disease outcomes in a 5/6 nephrectomy model

Chronic kidney disease (CKD) is defined by decreased glomerular filtration rate (GFR) or increased albumin excretion leading to renal injury. However, exercise training is an important non-pharmacological intervention that ameliorates and protects against Diabetes Mellitus, cardiovascular disease, and CKD.

AIM

Our aim was to evaluate the capability of resistance exercise training (RET) to improve CKD outcomes and the contribution of the renal and muscular Akt/mTOR signaling pathway for RET beneficial effects on a CKD model.

MAIN METHODS

Male Wistar rats were subjected to RET, followed for 10 weeks, and randomly divided into 5 groups: Sham: Sham-operated; sedentary and nephrectomy (5/6Nx) (SNS); exercising post-5/6Nx (SNE); exercising pre-5/6Nx (ENS); exercising pre- and post-5/6Nx (ENE). The systolic blood pressure (BP) was measured. Creatinine, proteinuria, and blood urea nitrogen (BUN) were evaluated. After euthanasia Renal and muscular Akt/mTOR signaling pathways were analyzed.

KEY FINDING

Our study showed that the SNS presented renal injury, hypertension, weight and muscular mass loss and a higher mortality rate. SNS group also decreased renal IL-10 and increased TNF-alfa and TGF-Beta. Renal AKT, mTOR, and rpS6 pathway were increased, PTEN was decreased on SNS. And muscular Akt and mTOR were decreased on SNS.

SIGNIFICANCE

The RET before and after the 5/6Nx ameliorates all these parameters mentioned above, suggesting that RET is a good non-pharmacological approach to diminish complications frequently found in CKD. We also suggest that the AKT-m-TOR pathway can play an important role in these beneficial outcomes of RET on the CKD animal model.

The metabolic profiles and body composition of lean metabolic associated fatty liver disease

BACKGROUND/PURPOSE

Metabolic associated fatty liver disease (MAFLD) is the commonest cause of chronic liver disease, which is associated with obesity and diabetes. However, it also occurs in lean individuals especially in Asian populations.

METHODS

The participants of Tzu Chi MAFLD cohort (TCMC) including health controls or MAFLD patients were enrolled. MAFLD was defined as fatty liver in imaging without hepatitis B virus, hepatitis C virus infection, drug, alcohol or other known causes of chronic liver disease. Lean MAFLD was defined as MAFLD in lean subjects (BMI < 23 kg/m²).

RESULTS

A total of 880 subjects were included for final analysis. Of 394 MAFLD patients, 65 (16.5%) patients were diagnosed as lean MAFLD. Lean MAFLD patients were elder, higher percentage of female gender, lower ALT, diastolic blood pressure, triglyceride, and waist circumference but higher HDL than non-lean MAFLD patients. Using binary regression analysis, elder age and lower waist circumference were associated with lean MAFLD. Compared with lean healthy controls, lean MAFLD patients had higher BMI, waist circumference, and percentage of hypertension. In body composition, fatty tissue index (FTI), lean tissue index (LTI) ,and total body water (TBW) were lower in lean MAFLD than non-lean MAFLD patients; but they were comparable with lean healthy controls.

CONCLUSIONS

The prevalence of lean MAFLD was 16.5% in this study population and it was higher in elder age, especially of female subjects. Lean MAFLD patients had different metabolic profiles compared with lean healthy controls, but different body composition compared with non-lean MAFLD patients.

The Association of Targeted Gut Microbiota with Body Composition in Type 2 Diabetes Mellitus

The association between body composition and gut microbiota in type 2 diabetes mellitus (DM) remains unknown. To elucidate the correlation of body composition and gut microbiota, we conducted a clinical study to enroll 179 patients with type 2 DM. Body composition of lean tissue index (LTI) and fat tissue index was measured by Body Composition Monitor. Eight pairs of 16S rRNA gene primers specific to Firmicutes, Bacteroidetes, the Clostridium leptum group, Bacteroides, Bifidobacterium, Akkermansia muciniphila, Escherichia coli, and Faecalibacterium prausnitzii were used to measure their abundance by quantitative polymerase chain reaction. The results showed that type 2 DM with higher abundance of phylum Firmicutes and a higher ratio of phyla Firmicutes to Bacteroidetes (phyla F/B ratio) had higher LTI. This significant correlation between phyla F/B ratio and LTI was especially evident in type 2 DM with high body mass index, and independent of glycemic control or dipeptidyl peptidase-4 inhibitor usage. In conclusion, our study demonstrated the positive association of LTI with the abundance of phylum Firmicutes and the phyla F/B ratio in type 2 DM.

The cut-off values of handgrip strength and lean mass index for sarcopenia among patients on peritoneal dialysis

Background

Sarcopenia is common and contributes to a high risk of mortality among general population. There is no consensus regarding the cut-off values for sarcopenia in terms of mortality among chronic kidney disease patients. This study aimed to explore and validate cut-off points of handgrip strength (HGS) and lean mass index (LMI) for estimating the risk of mortality in peritoneal dialysis (PD) patients.

Methods

This single-center prospective cohort study enrolled 1089 incident PD patients between October 2002 and July 2019. All patients were followed until death, transfer to hemodialysis, receiving renal transplantation or the end date of study (December 2019). All participants were randomly sampled to development cohort (70% participants) and validation cohort (30% participants), matched by gender and diabetes. Lean body mass was calculated by using the equation published by our center. Cubic spline regression analysis was used to examine the relationship between HGS or LMI values and mortality, and explore the cut-off points after adjusting for age, diabetes, cardiovascular disease and serum albumin in the development cohort. The derived cut-off values were verified by the agreement rate for predicting mortality and then compared with cut-off values from various clinical guidelines in the validation cohort.

Results

All 1089 patients were followed up with the median of 36.0 (18.0, 71.0) months. In the development cohort, cut-off points for predicting the higher mortality were derived as 24.5 kg and 14 kg of HGS for males and females, 16.7 kg/m² and 13.8 kg/m² of LMI for males and females respectively. In the validation cohort, these cut-off values significantly predicted worse outcomes, with HR 1.96 (1.35, 2.84) of HGS and HR 1.76 (1.26, 2.47) of LMI for all-cause mortality after multivariate adjustment. The newly derived cut-off points of HGS have numerically higher prognostic values in all-cause mortality compared with those from current clinical guidelines, and agreement rates of HGS were 65.2 versus 62.5–64.6 respectively.

Conclusions

The derived cut-off values of HGS and LMI have sufficient and better prognostic value in predicting all-cause mortality in PD patients compared with the cut-off values in the existing guidelines. These cut-off values are only validated in a single population, thus limiting the generalizability.

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.

Accuracy of surrogate methods to estimate skeletal muscle mass in non-dialysis dependent patients with chronic kidney disease and in kidney transplant recipients

BACKGROUND & AIMS

Bioelectrical impedance analysis (BIA) and anthropometric predictive equations have been proposed to estimate whole-body (SMM) and appendicular skeletal muscle mass (ASM) as surrogate for dual energy X-ray absorptiometry (DXA) in distinct population groups. However, their accuracy in estimating body composition in non-dialysis dependent patients with chronic kidney disease (NDD-CKD) and kidney transplant recipients (KTR) is unknown. The aim of this study was to investigate the accuracy and reproducibility of BIA and anthropometric predictive equations in estimating SMM and ASM compared to DXA, in NDD-CKD patients and KTR.

METHODS

A cross-sectional study including adult NDD-CKD patients and KTR, with body mass index (BMI) ≥18.5 kg/m². ASM and estimated SMM were evaluated by DXA, BIA (Janssen, Kyle and MacDonald equations) and anthropometry (Lee and Baumgartner equations). Low muscle mass (LowMM) was defined according to cutoffs proposed by guidelines for ASM, ASM/height² and ASM/BMI. The best performing equation as surrogate for DXA, considering both groups of studied patients, was defined based in the highest Lin's concordance correlation coefficient (CCC) value, the lowest Bland-Altman bias (<1.5 kg) combined with the narrowest upper and lower limits of agreement (LoA), and the highest Cohen's kappa values for the low muscle mass diagnosis.

RESULTS

Studied groups comprised NDD-CKD patients (n = 321: males = 55.1%; 65.4 ± 13.1 years; eGFR = 28.8 ± 12.7 ml/min) and KTR (n = 200: males = 57.7%; 47.5 ± 11.3 years; eGFR = 54.7 ± 20.7 ml/min). In both groups, the predictive equations presenting the best accuracy compared to DXA were SMM-BIA-Janssen (NDD-CKD patients: CCC = 0.88, 95%CI = 0.83-0.92; bias = 0.0 kg; KTR: CCC = 0.89, 95%CI = 0.86-0.92, bias = -1.2 kg) and ASM-BIA-Kyle (NDD-CKD patients: CCC = 0.87, 95%CI = 0.82-0.90, bias = 0.7 kg; KTR: CCC = 0.89, 95%CI = 0.86-0.92, bias = -0.8 kg). In NDD-CKD patients and KTR, LowMM frequency was similar according to ASM-BIA-Kyle versus ASM-DXA. The reproducibility and inter-agreement to diagnose LowMM using ASM/height² and ASM/BMI estimated by BIA-Kyle equation versus DXA was moderate (kappa: 0.41-0.60), in both groups. Whereas female patients showed higher inter-agreement (AUC>80%) when ASM/BMI index was used, male patients presented higher AUC (70-74%; slightly <80%) for ASM/height² index.

CONCLUSIONS

The predictive equations with best performance to assess muscle mass in both NDD-CKD patients and KTR was SMM-BIA by Janssen and ASM-BIA by Kyle. The reproducibility to diagnose low muscle mass, comparing BIA with DXA, was high using ASM/BMI in females and ASM/height² in males in both groups.

Relationship Between Epicardial Adipose Tissue and Body Composition as Determined by Multi-Frequency Bioelectrical Impedance Analysis in Patients with Stage 5 Chronic Kidney Disease

Background

The main cause of mortality among chronic kidney disease (CKD) patients is cardiovascular disease (CVD). Epicardial adipose tissue (EAT) is considered to be novel cardiovascular risk factor. We assessed EAT in non-dialyzed stage 5 CKD patients and explored the association of EAT with body composition as determined by multi-frequency BIA.

Material/Methods

The present included 70 stage 5 CKD patients who had not undergone dialysis and 40 healthy control subjects. EAT thickness was assessed by echocardiography. Hydration status and body composition were evaluated by multi-frequency bioelectrical impedance analysis.

Results

Stage 5 CKD patients had significantly higher EAT thickness than healthy subjects (6.56±1.18 vs. 4.05±1.45, p<0.001). Fat tissue mass, systolic blood pressure (SBP), age, fat tissue index, and body mass index were positively correlated with EAT thickness in the CKD patient group (p<0.05). Lean tissue mass, lean tissue index (LTI), and high-density lipoprotein (HDL) were negatively correlated with EAT thickness in the CKD patient group (p<0.05). Stepwise multiple regression analysis showed that age, SBP, and LTI were independently associated with EAT thickness in CKD patients.

Conclusions

We found significantly higher EAT thickness in stage 5 CKD patients who were not on dialysis compared to healthy controls. EAT was significantly associated with age, SBP, and LTI in CKD patients. Interventions to reduce the risk factors associated with EAT thickness might protect against CVD disease in CKD patients.

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.

Serum creatinine to cystatin C ratio predicts skeletal muscle mass and strength in patients with non-dialysis chronic kidney disease

BACKGROUND & AIMS

Muscle wasting is highly prevalent in patients with chronic kidney disease (CKD). However, the assessment of skeletal muscle mass and strength in clinical settings is not commonly available. We aimed to evaluate the feasibility of serum creatinine/cystatin C (Cr/CysC) ratio in the assessment of muscle wasting.

METHODS

In 272 patients with CKD aged 66.5 ± 15.1 years, skeletal muscle mass and handgrip strength (HGS) were assessed. Skeletal muscle index (SMI) was calculated as skeletal muscle mass/height². Low muscle mass was defined as SMI below the sex-specific 10th percentile of study population and low handgrip strength as less than 26 Kg for men and 18 Kg for women.

RESULTS

The Cr/CysC ratio was significantly lower in both the low SMI and low HGS groups. Moreover, the Cr/CysC ratio correlated with SMI (r = .306, p < .001) and HGS (r = .341, p < .001). After adjusting for confounding factors, age, sex, waist circumference, body fat mass, and Cr/CysC ratio were independently associated with SMI, whereas age, sex, diabetes, hemoglobin, estimated glomerular filtration rate, urine protein/creatinine ratio, SMI, and Cr/CysC ratio were independently associated with HGS.

CONCLUSIONS

Cr/CysC ratio appears to be a promising surrogate marker for detecting muscle wasting in patients with CKD. Further studies are needed to extend our findings.

Body-mass index and the risk of albuminuria in hypertensive patients with a poor estimated glomerular filtration rate and the potential role of diabetes mellitus

BACKGROUND

Obesity-related to metabolic syndrome was associated with a greater risk for development of chronic kidney disease (CKD). We aimed to assess the association between obesity and micro/macroalbuminuria in hypertensive patients with a poor estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2.

METHODS

One hundred old patients (median age 79 years ± inter-quartile range 68-84.7) with manifested hypertension (systolic blood pressure ≥ 130 mmHg and/or diastolic blood pressure ≥ 85 mmHg) and a permanently poor eGFR for a duration time more than 3 months were enclosed. Albuminuria was defined as urinary albumin-to-creatinine ratio (ACR) ≥ 30 mg/gr and it was classified according to KDIGO 2012. The obesity was defined by a high body mass index (BMI>30 kg/m2). The waist circumference, HDL-C, triglycerides and serum glucose were measured. Chi-square tests and an adjusted model were performed.

RESULTS

Chi-square tests showed significant association between classified albuminuria and both obesity and high serum triglycerides (x2 = 7.2, p = 0.02 and x2 = 8.3, p = 0.01 respectively). However, the adjusted model for the prediction of albuminuria showed that the presence of a high BMI was a non-significant risk factor, although diabetes mellitus and eGFR value were found to be significant risk factors (p = 0.03, OR = 4.3, 1.2-22.07 and p = 0.04, OR = 0.9, 0.9-1.007 respectively) adjusting to covariates including the high waist circumference.

CONCLUSION

Obesity defined by a high BMI was not found to be a significant risk factor for micro/macroalbuminuria in hypertensive patients with a poor estimated glomerular filtration rate, when diabetes mellitus and the low eGFR value act as confounders.

Umbilical Cord SFRP5 Levels of Term Newborns in Relation to Normal and Excessive Gestational Weight Gain

Among the new adipokines, secreted frizzled-related protein 5 (SFRP5) is considered to prevent obesity and insulin resistance. The umbilical cord SFRP5 levels have not yet been investigated. The main aim of the study was to investigate whether the umbilical cord SFRP5 concentrations are altered in term neonates born to mothers with excessive gestational weight gain (EGWG). Two groups of subjects were selected depending on their gestational weight gain, i.e. 28 controls and 38 patients with EGWG. Umbilical cord and maternal serum SFRP5 levels were lower in the EGWG group. Umbilical cord SFRP5 concentrations were directly associated with the maternal serum SFRP5, hemoglobin A1c and lean tissue index, umbilical cord leptin levels, as well as newborns’ anthropometric measurements in the EGWG subjects. In multiple linear regression models performed in all the study participants, umbilical cord SFRP5 concentrations depended positively on the maternal serum SFRP5, ghrelin, and leptin levels and negatively on the umbilical cord ghrelin levels, low-density lipoprotein cholesterol, pre-pregnancy body mass index, and gestational weight gain. EGWG is associated with disturbances in SFRP5 concentrations. Obstetricians and midwives should pay attention to nutrition and weight management during pregnancy.

Body composition is associated with clinical outcomes in patients with non-dialysis-dependent chronic kidney disease

An inverse relationship between body mass index (BMI) and mortality (the obesity paradox) has been found in patients with non-dialysis-dependent chronic kidney disease (CKD). However, it is unclear whether increased muscle mass or body fat confers the survival advantage. To resolve this we investigated the impact of body makeup on a composite outcome of death or cardiovascular events in a prospective cohort of 326 patients with stage 3-5 CKD not yet on dialysis. Lean mass and body fat were determined using the Body Composition Monitor, a multifrequency bioimpedance spectroscopy device, and were expressed as the lean tissue or fat tissue index, respectively. Patients were stratified as High (above median) or Low (below median) BMI, High or Low lean tissue index, or as High or Low fat tissue index. During a median follow-up of 4.6 years, there were 40 deaths and 68 cardiovascular events. In Cox proportional hazards models, a High lean tissue index, but not High BMI or High fat tissue index, predicted a lower risk of both the composite or its component outcomes (reference: below median). When patients were further stratified into four distinct body composition groups based on both the lean and fat tissue index, only the High lean/fat tissue index group had a significantly lower risk of the composite outcome (hazard ratio 0.36, 95% confidence interval 0.14-0.87; reference: Low lean/fat tissue index group). Thus, the lean tissue index can provide better risk prediction than the BMI alone in non-dialysis-dependent patients with CKD. The High lean/fat tissue index appears to be associated with best outcomes. An optimal body composition for improving the prognosis of CKD needs to be determined.

Satellite cell function, intramuscular inflammation and exercise in chronic kidney disease

Skeletal muscle wasting is a common feature of chronic kidney disease (CKD) and is clinically relevant due to associations with quality of life, physical functioning, mortality and a number of comorbidities. Satellite cells (SCs) are a population of skeletal muscle progenitor cells responsible for accrual and maintenance of muscle mass by providing new nuclei to myofibres. Recent evidence from animal models and human studies indicates CKD may negatively affect SC abundance and function in response to stimuli such as exercise and damage. The aim of this review is to collate recent literature on the effect of CKD on SCs, with a particular focus on the myogenic response to exercise in this population. Exercise is widely recognized as important for the maintenance of healthy skeletal muscle mass and is increasingly advocated in the care of a number of chronic conditions. Therefore a greater understanding of the impact of uraemia upon SCs and the possible altered myogenic response in CKD is required to inform strategies to prevent uraemic cachexia.

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.

Normal-weight obesity and clinical outcomes in nondiabetic chronic kidney disease patients: a cohort study

Background

Normal-weight obesity (NWO), defined by a normal body mass index (BMI) and high body fat percentage, has been shown to be associated with cardiometabolic dysfunction and an increased risk of cardiovascular disease and mortality in the general population. However, little is known about the clinical implications of NWO among patients with chronic kidney disease (CKD).

Objective

The aim of this study was to assess the characteristics and outcomes of nondiabetic CKD patients with NWO.

Design

A total of 178 nondiabetic patients with stages 3-5 CKD were prospectively followed for a median of 4.9 y. The patients were classified into 3 different adiposity phenotypes: nonobese [BMI (in kg/m2) <25 and fat mass percentage (FM%) ≤25% for men or ≤35% for women], NWO (BMI <25 and FM% >25% for men or >35% for women), and preobese-obese (BMI ≥25). FM% was determined using the Body Composition Monitor, a multifrequency bioimpedance spectroscopy device. The outcome was a composite of cardiovascular events or all-cause mortality.

Results

The prevalence of NWO was 28.1% among nondiabetic CKD patients with a normal BMI. NWO patients were older, had lower lean body mass, and had higher plasma interleukin-6 concentrations than nonobese patients. However, homeostatic model assessment for insulin resistance levels did not differ between the 2 groups. NWO patients showed a significant 3-fold higher risk of the composite outcome (HR 2.96, 95% CI: 1.13, 7.77; P < 0.05) than did nonobese patients in the fully adjusted model. Preobese-obese patients were not at increased risk compared to nonobese patients.

Conclusions

NWO was associated with the worst prognosis among the 3 different adiposity phenotypes in nondiabetic CKD patients. Our findings suggest the importance of using direct measures of adiposity for risk assessment in CKD patients who are normal-weight. This trial was registered at clinicaltrials.gov as NCT03285074.

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.