Obese sarcopenia in patients with end-stage renal disease is associated with inflammation and increased mortality

Obesity and Metabolic Health in CKD

Obesity is a worldwide epidemic with a future projected growth of 40% over 10 years. Obesity increases the risk of diabetes, hypertension, and cardiovascular disease, and it also leads to higher risk of CKD, through both direct and indirect mechanisms. Although obesity is a feature of overnutrition and is associated with poor outcomes in the general population, obese individuals with CKD often display complex metabolic patterns such as sarcopenic obesity, and obesity can be associated with better survival in individuals with advanced CKD. Weight loss interventions are proven to improve glycemic control and cardiovascular risk factors, and successful weight loss is associated with improved albuminuria in patients with preexisting CKD. The long-term effects of weight loss interventions on kidney function and on survival in patients with CKD are less well studied, and hence, such interventions should be individualized.

Potential Determinants of Subjective Global Assessment Among Patients on Maintenance Hemodialysis

OBJECTIVE

The Subjective Global Assessment (SGA) is a validated tool for identifying nutritional status in patients receiving maintenance hemodialysis (MHD), but it is not without limitations. Current research identifies additional clinical characteristics such as phase angle (PhA) associated with SGA. This study aimed to assess the overall correlation between PhA and SGA; associations between PhA and SGA by body mass index, and to identify clinical characteristics associated with SGA.

DESIGN AND METHODS

This is a secondary analysis of the Rutgers Nutrition & Kidney Database, which enrolled participants from four primary studies that included adults diagnosed with chronic kidney disease who were receiving MHD. Multivariable binary logistic regression analyses were conducted to estimate odds ratio (OR) and corresponding 95% confidence intervals (CIs).

RESULTS

The study sample included 60.0% males with 81.1% of the sample identifying as African American. Additionally, 38.9% were obese according to the body mass index classification, and 57.0% were moderately malnourished. Patients with obesity had 44% lower odds of being moderately malnourished (OR = 0.56, 95% CI = 0.37, 0.85). In the model adjusted for age and ethnicity and other clinical characteristics, increasing PhA values by one unit was associated with 28% lower odds (OR = 0.72, 95% CI = 0.53, 0.97) of being moderately malnourished while increasing waist circumference (WC) values by one unit was associated with 12% higher odds (OR = 1.12; 95% CI = 1.06, 1.19) of being moderately malnourished than well-nourished. In this fully adjusted model, increasing fat free mass (FFM, OR = 0.95, 95% CI = 0.91, 0.99) and fat mass (FM, OR = 0.92, 95% CI = 0.87, 0.97) by 1 kg was also associated with 5% and 8% lower odds of being moderately malnourished, respectively.

CONCLUSION

PhA and SGA were significantly associated only among patients classified as obese. PhA, WC, FM, and FFM were identified as potential clinical determinants of SGA. Patients receiving MHD and who have obesity may benefit from utilizing SGA along with WC, PhA, FM, and FFM to assess nutritional status.

Clinical and novel insights into risk factors for sarcopenia in dialysis patients: a systematic review and meta-analysis

OBJECTIVE

We employed a meta-analysis to investigate the risk factors associated with sarcopenia in patients undergoing dialysis.

METHODS

We conducted a search in PubMed, Embase, Cochrane Library, and Web of Science databases. Inclusion criteria included case-control and cohort studies on risk factors for sarcopenia in dialysis patients. The search period spanned from the inception of each database to September 20, 2024. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS). Data analysis was performed using Stata 15.0.

RESULT

A total of 625 articles were screened, with 610 articles excluded based on predefined eligibility criteria, resulting in 15 articles involving 2904 individuals were included in the final analysis, meta-analysis results indicate that older dialysis patients [SMD = 0.76, 95% CI (0.54, 0.99), I2 = 81%, P = 0.001], those with a lower BMI [SMD = -0.50, 95% CI (-0.80, -0.20), I2% = 87.4%, P = 0.02], a lower SMI [SMD = -2.67, 95% CI (-3.87, -1.47), I2% = 98.2%, P = 0.001], and those with diabetes [OR = 1.43, 95% CI (1.13, 1.82), I2% = 48.8%, P = 0.03] are more likely to develop sarcopenia.

CONCLUSION

Based on current research, our study found that elderly dialysis patients, those with a lower BMI, lower SMI, and diabetic patients are more likely to develop sarcopenia. These findings highlight the necessity of early intervention for these high-risk groups. However, the study has limitations. Future research should address these limitations and investigate the mechanisms linking these risk factors to sarcopenia to develop targeted prevention and treatment strategies.

The role of lean body mass in predicting mortality in hemodialysis patients across different age groups

Lean body mass (LBM) serves as an indicator of muscle mass in body composition. Recently, studies have revealed increased mortality rates in dialysis patients with low LBM. However, studies analyzing the impact of age on LBM and mortality in dialysis patients remain limited. This study analyzed data from 26,625 adult hemodialysis patients registered in the Korean Society of Nephrology (KSN) registry from 2001 to 2020. We used the lean body mass index (LBMI), standardized by the square of height, to normalize lean body mass. Patients were first categorized by age group (20-49, 50-69, and ≥ 70 years). Subsequently, patients were categorized into quartile groups based on their LBMI (≤ 15.55, 15.55 < LBMI ≤ 16.52, 16.52 < LBMI ≤ 17.59, and > 17.59). This study revealed that the lowest LBMI group (≤ 15.55) was associated with decreased survival across all age groups, with this trend being particularly prominent in the older age groups. Within the 20-49 age group, factors such as diabetes exhibited a notable influence on mortality rates among hemodialysis patients. In the age group over 50, a low LBMI (≤ 15.55) had a greater impact on mortality rates in hemodialysis patients than diabetes. Understanding the importance of LBM in older patients undergoing dialysis is crucial for improving their prognosis.

Assessing Patients beyond the Simple Optics of BMI: The Concomitant Role of Sarcopenia and BMI in Predicting Kidney Transplant Outcomes

BACKGROUND

Body composition is associated with prognosis in many clinical settings, and patients undergoing kidney transplantation are often high risk with multiple comorbidities. We aimed to assess the effect of sarcopenia and body composition on transplant outcomes.

METHODS

We performed a retrospective analysis of 274 kidney transplants with CT scans within 3 years of transplantation. The skeletal muscle index (SMI) at the L3 vertebrae was used to evaluate sarcopenia (SMI < 40.31 cm2/m2 in males, <30.88 cm2/m2 in females). Sarcopenia, body mass index (BMI), and the visceral-to-subcutaneous-fat ratio (VSR) were assessed separately. We also used a composite BMI/sarcopenia measurement in four patient groups: BMI < 25/Non-Sarcopenic, BMI < 25/Sarcopenic, BMI > 25/Non-Sarcopenic, and BMI > 25/Sarcopenic. The outcomes measured were eGFR (1 and 3 months; and 1, 3, and 5 years), delayed graft function (DGF), rejection, major adverse cardiovascular events (MACE), and post-operative complications.

RESULTS

Sarcopenia was associated with an increased 1-year risk of MACE (OR 3.41, p = 0.036). BMI alone had no effect on function, DGF, MACE, or on other complications. High VSR was associated with a lower risk of DGF (OR 0.473, p = 0.016). When sarcopenia and BMI were assessed together, the BMI > 25/sarcopenic patients had the poorest outcomes, with increased risk of MACE (OR 26.06, p = 0.001); poorer eGFR at 1, 3, 12, and 36 months; (p < 0.05 at all timepoints), and poorer graft survival (p = 0.002).

CONCLUSIONS

Sarcopenia alone is associated with an increased risk of MACE. Overweight sarcopenic patients are additionally at increased risk of graft loss and have poorer graft function for up to three years.

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.

Neutrophil-to-lymphocyte ratio is associated with sarcopenia risk in overweight maintenance hemodialysis patients

Neutrophil-to-lymphocyte ratio (NLR), a novel inflammatory marker, is strongly associated with the risk of sarcopenia. Notably, being overweight has been found to accelerate the loss of skeletal muscle mass and function in chronic kidney disease (CKD) patients. However, the effect of overweight status on the relationship between NLR and sarcopenia risk has been poorly studied. We conducted a cross-sectional study at a hemodialysis center in Chengdu, China, from September to December 2022. The prevalence of sarcopenia was determined according to the Asian Working Group for Sarcopenia (AWGS). Participants were stratified based on body mass index (BMI) categories for the Asian population (non-overweight < 23 kg/m2 and overweight ≥ 23 kg/m2). 272 participants aged 18-85 years were included, with 144 being male. The overall prevalence of sarcopenia was 32.72% (89/272). After adjusting for covariates, NLR was significantly associated with sarcopenia risk in overweight participants (OR 1.60, 95% CI 1.15-2.24, p = 0.006), whereas it was not significant in the non-overweight group (OR 0.88, 95% CI 0.70-1.10, p = 0.254). Moreover, subgroup analysis showed a significant interactive association between NLR and overweight status with respect to sarcopenia. These findings emphasize the potential significance of regular screening of NLR for the early detection of sarcopenia in overweight patients undergoing maintenance hemodialysis.

Nutrition Management in Geriatric Patients with CKD

Sarcopenia, defined as age-related decline in skeletal muscle mass and functional capacity, is a hallmark nutritional abnormality observed in patients with moderate-to-advanced CKD. Uremic state and associated medical conditions also predispose older patients with CKD to protein-energy wasting, a nutritional abnormality that could include sarcopenia. Prevention of protein and energy depletion and replenishing the already low nutritional reserves elderly patients with CKD should focus on conventional and innovative strategies. This review aims to provide an overview of the mainstay of nutritional therapy in this patient population, such as intake of adequate amounts of protein and energy along with preserving fluid, electrolyte, and mineral balance, and to discuss more innovative interventions to aid these approaches.

Association Between Changes in Depressive Symptoms and Sarcopenia: Findings From a Nationwide Cohort Study

OBJECTIVES

The aim of this study was to investigate the association between changes in depressive symptoms and sarcopenia by repeated measures of depressive symptoms at a follow-up visit every 2 years.

DESIGN

Cross-sectional design and longitudinal design.

SETTING AND PARTICIPANTS

We conducted a cross-sectional and longitudinal study using data from the China Health and Retirement Longitudinal Study, which is a representative national survey. A total of 12,287 participants were included in Wave 1 (2011-2012) for the cross-sectional analysis, followed by a total of 5285 participants in Wave 2 (2013-2014) and Wave 3 (2015-2016) for the longitudinal analysis based on the cross-sectional analysis.

METHODS

Depressive symptoms were measured by the 10-item Center for the Epidemiological Studies of Depression Short Form. Sarcopenia was defined according to the Asian Sarcopenia Working Group criteria (AWGS 2019). Changes in depressive symptoms in Wave 1 and Wave 2 were used as exposure, and sarcopenia in Wave 3 was used as outcome. Cox proportional hazards regression model was used to test the relationship between changes in depressive symptoms and sarcopenia.

RESULTS

In cross-sectional analysis, depression was significantly associated with sarcopenia (odds ratio, 1.27; 95% CI, 1.10-1.48). In subsequent longitudinal analyses, a total of 174 sarcopenia events occurred, and those with increased depressive symptoms and persistent depressive symptoms were at higher risk for sarcopenia than those without depressive symptoms, with multivariable-adjusted hazard ratios of 1.65 (95% CI, 1.00-2.73) and 1.68 (95% CI, 1.06-2.68), respectively.

CONCLUSIONS AND IMPLICATIONS

People with increased depressive symptoms and persistent depressive symptoms may have a higher risk of developing sarcopenia over time. In the future, more research is needed to confirm the mechanism by which long-term changes in depression contribute to the risk of sarcopenia, and to propose preventive measures accordingly.

Decreased intracellular water is associated with sarcopenic obesity in chronic haemodialysis patients

OBJECTIVE

To explore the association between intracellular water (ICW) and sarcopenic obesity in patients undergoing chronic haemodialysis (HD).

METHODS

A multicentre, cross-sectional study of 3354 adult chronic HD patients was conducted in 20 haemodialysis centres from June 1, 2021, to August 30, 2021. The diagnosis of sarcopenic obesity was made according to the revised Asian Working Group's definition of sarcopenia combined with obesity per the body fat percentage definition. Body composition was evaluated by a body composition monitor using bioimpedance spectroscopy. Multiple logistic regression models, stratified analyses, interactive analyses, and receiver-operating characteristic analyses were conducted.

RESULTS

A total of 752 patients were diagnosed with sarcopenic obesity among 3354 participants. The patients were grouped by sex-specific ICW median levels, and the prevalence of sarcopenic obesity was significantly higher in the low ICW group than in the high ICW group (41.3%vs 3.0%). Decreased ICW was significantly associated with sarcopenic obesity. The association remained statistically significant even after adjusting for dialysis vintage, age, body mass index, biochemical indicators, and various medical histories. The odds ratios of the low ICW group were much higher than those of the high ICW group in both males and females (P for trend < 0.001). The association was stable across subgroups, and the interaction analysis showed that age, body mass index and history of diabetes had interactive roles in the association between ICW and sarcopenic obesity (P for interaction < 0.05). Furthermore, the ICW cut-off values for identifying sarcopenic obesity were 19.1 kg and 14.5 kg for males and females, respectively.

CONCLUSION

Decreased ICW was an independent risk factor for sarcopenic obesity in chronic HD patients. The measurement of ICW by bioimpedance spectroscopy might be a non-invasive and valid means for identifying the risk of future sarcopenic obesity in HD patients.

Nutritional Strategies to Prevent Muscle Loss and Sarcopenia in Chronic Kidney Disease: What Do We Currently Know?

Loss of muscle mass is an extremely frequent complication in patients with chronic kidney disease (CKD). The etiology of muscle loss in CKD is multifactorial and may depend on kidney disease itself, dialysis, the typical chronic low-grade inflammation present in patients with chronic kidney disease, but also metabolic acidosis, insulin resistance, vitamin D deficiency, hormonal imbalances, amino acid loss during dialysis, and reduced dietary intake. All these conditions together increase protein degradation, decrease protein synthesis, and lead to negative protein balance. Aging further exacerbates sarcopenia in CKD patients. Nutritional therapy, such as protein restriction, aims to manage uremic toxins and slow down the progression of CKD. Low-protein diets (LPDs) and very low-protein diets (VLPDs) supplemented with amino acids or ketoacids are commonly prescribed. Energy intake is crucial, with a higher intake associated with maintaining a neutral or positive nitrogen balance. Adequate nutritional and dietary support are fundamental in preventing nutritional inadequacies and, consequently, muscle wasting, which can occur in CKD patients. This review explores the causes of muscle loss in CKD and how it can be influenced by nutritional strategies aimed at improving muscle mass and muscle strength.

Formerly bile-farmed bears as a model of accelerated ageing

Bear bile-farming is common in East and Southeast Asia and this farming practice often results in irreversible health outcomes for the animals. We studied long-term effects of chronic bacterial and sterile hepatobiliary inflammation in 42 Asiatic black bears (Ursus thibetanus) rescued from Vietnamese bile farms. The bears were examined under anesthesia at least twice as part of essential medical interventions. All bears were diagnosed with chronic low-grade sterile or bacterial hepatobiliary inflammation along with pathologies from other systems. Our main finding was that the chronic low-grade inflammatory environment associated with bile extraction in conjunction with the suboptimal living conditions on the farms promoted and accelerated the development of age-related pathologies such as chronic kidney disease, obese sarcopenia, cardiovascular remodeling, and degenerative joint disease. Through a biomimetic approach, we identified similarities with inflammation related to premature aging in humans and found significant deviations from the healthy ursid phenotype. The pathological parallels with inflammageing and immuno-senescence induced conditions in humans suggest that bile-farmed bears may serve as animal models to investigate pathophysiology and deleterious effects of lifestyle-related diseases.

Chronic kidney disease-related sarcopenia as a prognostic indicator in elderly haemodialysis patients

BACKGROUND

The mortality of dialysis patients greatly exceeds that of the general population and identifying predictive factors for mortality may provide opportunities for earlier intervention. This study assessed the influence of sarcopenia on mortality in patients on haemodialysis.

METHODS

This prospective, observational study enrolled 77 haemodialysis patients aged 60 years and over, of whom 33 (43%) were female, from two community dialysis centres. Baseline demographic and laboratory data were collected, and sarcopenia was diagnosed using grip strength, muscle mass by bioimpedance analysis (BIA) and muscle function by timed up-and-go according to European Working Group on Sarcopenia in Older People criteria. Nutritional status was assessed using a subjective nutritional assessment score, comprising functional changes in weight, appetite, gastrointestinal symptoms and energy.. A comorbidity score (maximum 7 points) was derived from the presence or absence of hypertension, ischaemic heart disease, vascular disease (cerebrovascular disease, peripheral vascular disease, and abdominal aortic aneurysm), diabetes mellitus, respiratory disease, a history of malignancy and psychiatric disease. Outcomes over six years were linked to the Australian and New Zealand Dialysis and Transplant Registry.

RESULTS

The median participant age was 71 years (range 60-87). Probable and confirmed sarcopenia was present in 55.9% and severe sarcopenia with reduced functional testing in 11.7%. Over 6 years, overall mortality was 50 of the 77 patients (65%), principally from cardiovascular events, dialysis withdrawal and infection. There were no significant survival differences between patients with no, probable, confirmed, or severe sarcopenia, or between tertiles of the nutritional assessment score. After adjustment for age, dialysis vintage, mean arterial pressure (MAP) and the total comorbidity score, no sarcopenia category predicted mortality. However, the total comorbidity score [Hazard Ratio (HR) 1.27, Confidence Intervals (CI) 1.02, 1.58, p = 0.03] and MAP (HR 0.96, CI 0.94, 0.99, P = < 0.01) predicted mortality.

CONCLUSION

Sarcopenia is highly prevalent in elderly haemodialysis patients but is not an independent predictor of mortality. Haemodialysis patients have multiple competing risks for mortality which, in this study, was predicted by a lower MAP and a higher total comorbidity score.

TRIAL REGISTRATION

Recruitment commenced December 2011. The study was registered 10.01.2012 with the Australian New Zealand Clinical Trials Registry (ACTRN12612000048886).

Adipose tissue metabolic changes in chronic kidney disease

Adipose tissue is a complex organ whose functions go beyond being an energy reservoir to sustain proper body energy homeostasis. Functioning as an endocrine organ, the adipose tissue has an active role in the body's metabolic balance regulation through several secreted factors generally termed as adipokines. Thus, adipose tissue dysregulation in chronic kidney disease (CKD) can have a deep impact in the pathophysiology of diseases associated with metabolic dysregulation including metabolic syndrome, insulin resistance (IR), atherosclerosis, and even cachexia. CKD is a progressive disorder linked to increased morbidity and mortality. Despite being characterized by renal function loss, CKD is accompanied by metabolic disturbances such as dyslipidemia, protein energy wasting, chronic low-grade inflammation, IR, and lipid redistribution. Thus far, the mechanisms by which these changes occur and the role of adipose tissue in CKD development and progression are unclear. Further understanding of how these factors develop could have implications for the management of CKD by helping identify pharmacological targets to improve CKD outcomes.

Association between low handgrip strength and obesity with mortality in peritoneal dialysis patients

The association between sarcopenia and obesity in peritoneal dialysis (PD) patients is more complex than that of the general population. The aim of this study was, therefore, to evaluate the association of patient survival with sarcopenia or sarcopenic components and obesity in groups of patients with PD. We retrospectively analyzed a dataset from 199 prevalent PD patients. Measurements including handgrip strength (HGS), appendicular lean mass index, and baseline characteristics, were obtained during the period of study. Patients were divided into four groups according to their HGS and obesity: NH-NO (normal HGS and non-obesity, n = 60), NH-O (normal HGS and obesity, n = 31), LH-NO (low HGS and non-obesity, n = 71), and LH-O (low HGS and obesity, n = 37). The median follow-up interval was 17 months. The Kaplan-Meier curve analysis showed that the LH-O group had the poorest patient survival outcome among the four groups (P < 0.001). The NH-NO group had a better patient survival outcome compared with the LH-NO group. Univariate and multivariate Cox regression analyses showed that the LH-O group had the highest mortality rate compared with the other groups. The NH-NO group had lower mortality compared with the LH-NO group. The present study demonstrated that obesity with low HGS was associated with the greatest mortality rate in groups defined by HGS and obesity.

Sarcopenic Obesity Versus Nonobese Sarcopenia in Hemodialysis Patients: Differences in Nutritional Status, Quality of Life, and Clinical Outcomes

OBJECTIVE

Sarcopenia and sarcopenic obesity (SO) are linked to unfavorable prognosis in maintenance hemodialysis (MHD) populations. We tested whether nonobese sarcopenia and SO, as different stages of extreme protein-energy wasting, have different prognoses.

METHODS

In this prospective observational study, 261 MHD patients were recruited from October 2010 to April 2012 and followed until October 2020. Two definitions were used to diagnose sarcopenia: the European Working Group on Sarcopenia in Older People consensus and the Foundation for the National Institutes of Health (FNIH) Biomarkers Consortium criteria. Obesity was determined as the percentage of total body fat, ≥27% for men and ≥38% for women. Data for all-cause and cardiovascular morbidity and mortality, baseline nutrition markers, inflammation and oxidative stress, adipokines, body composition parameters, handgrip strength, and quality of life (QoL) scores were measured.

RESULTS

According to European Working Group on Sarcopenia in Older People, 115 (44.1%) patients were sarcopenic and 120 (46.0%) according to FNIH definitions. Of them, 28.4% and 34.5% were SO, respectively. Higher levels of albumin, creatinine, uric acid, leptin, phase angle, better nutritional scores, and lower adiponectin levels characterized SO patients compared with nonobese sarcopenic patients regardless of indexing method. Better QoL scores were noted in SO compared with nonobese sarcopenic patients using the FNIH sarcopenia criteria. The hazard of all-cause death, cardiovascular death, and first cardiovascular event for patients with SO was lower compared with the nonobese patients after multivariate adjustments. Statistical significance of these associations disappeared after including fat mass in multivariate models.

CONCLUSIONS

MHD patients with SO have better nutritional status and prognosis for cardiovascular events, all-cause and cardiovascular disease mortality, and possibly better QoL compared with nonobese sarcopenic MHD patients. The better prognosis appears to be entirely due to the excess fat, which is protective in sarcopenic MHD patients similar to that described in the entire MHD population.

The change in Geriatric Nutritional Risk Index is associated with mortality in patients who start hemodialysis: Korean Renal Data Registry, 2016-2018

Malnutrition is common in patients undergoing hemodialysis (HD) and is associated with mortality. This study aimed to investigate the association between changes in nutrition status measured by the Geriatric Nutritional Risk Index (GNRI) and all-cause mortality in patients who started HD. A nationwide retrospective cohort study was conducted based on the Korean Renal Data System database. Patients who started HD from January 2016 to December 2018, and were eligible for GNRI and GNRI trend were included. GNRI trend was a longitudinal change of GNRI, assessed by random slope in a mixed-effect model. Positive and negative random slopes in each patient were assigned to positive and negative GNRI trends. A total of 2313 patients were included and median follow-up period was 3.1 (2.6-3.7) years. GNRI values decreased over time (estimate - 1.212, 95% confidence interval (CI) - 1.116-0.692) and positive GNRI trend was associated with survival benefit (hazard ratio 0.55, 95% CI 0.36-0.84) after multivariate adjustment. These findings show that serial GNRI assessment, besides GNRI, is a useful prognostic factor for mortality in patients who start HD.

Sarcopenia and cardiovascular disease in patients with and without kidney disease: what do we know?

Cardiovascular disease (CVD) incidence is high in patients with chronic kidney disease (CKD) and is the most frequent cause of mortality in this population. Advanced age, hypertension, uremic toxins, endothelial dysfunction, atherosclerosis, hyperhomocysteinemia, oxidative stress, and inflammation are among the leading causes of increased CVD in advanced stages of CKD. Although defined as a decrease in muscle strength associated with aging, sarcopenia is also prevalent in CKD patients. Sarcopenia causes physical disability, low quality of life, and mortality. Regular exercise and nutritional supplementation may slow the progression of sarcopenia. Recent studies have shown that sarcopenia increases the risk of CVD and mortality in people with or without kidney disease. This review discusses the relationship between sarcopenia and CVD in light of the current literature.

Prevalence of Sarcopenia and Its Impact on Cardiovascular Events and Mortality among Dialysis Patients: A Systematic Review and Meta-Analysis

Sarcopenia in end-stage kidney disease patients requiring dialysis is a frequent complication but remains an under-recognized problem. This meta-analysis was conducted to determine the prevalence of sarcopenia and explored its impacts on clinical outcomes, especially cardiovascular events, and mortality in dialysis patients. The eligible studies were searched from PubMed, Scopus, and Cochrane Central Register of Controlled trials up to 31 March 2022. We included studies that reported the interested outcomes, and the random-effects model was used for analysis. Forty-one studies with 7576 patients were included. The pooled prevalence of sarcopenia in dialysis patients was 25.6% (95% CI 22.1 to 29.4%). Sarcopenia was significantly associated with higher mortality risk (adjusted OR 1.83 (95% CI 1.40 to 2.39)) and cardiovascular events (adjusted OR 3.80 (95% CI 1.79 to 8.09)). Additionally, both low muscle mass and low muscle strength were independently related to increased mortality risk in dialysis patients (OR 1.71; 95% CI (1.20 to 2.44), OR 2.15 (95% CI 1.51 to 3.07)), respectively. This meta-analysis revealed that sarcopenia was highly prevalent among dialysis patients and shown to be an important predictor of cardiovascular events and mortality. Future intervention research to alleviate this disease burden in dialysis patients is needed.

Obesity and Chronic Kidney Disease A Current Review

Background

Obesity poses significant challenges to healthcare globally, particularly through its bi-directional relationship with co-morbid metabolic conditions such as type 2 diabetes and hypertension. There is also emerging evidence of an association between obesity and chronic kidney disease (CKD) which is less well characterized.

Methods

A literature search of electronic libraries was conducted to identify and present a narrative review of the interplay between obesity and CKD.

Findings

Obesity may predispose to CKD directly as it is linked to the histopathological finding of obesity-related glomerulopathy and indirectly through its widely recognized complications such as atherosclerosis, hypertension, and type 2 diabetes. The biochemical and endocrine products of adipose tissue contribute to pathophysiological processes such as inflammation, oxidative stress, endothelial dysfunction, and proteinuria. The prevention and management of obesity may prove critical in counteracting both the development and advancement of CKD. Moreover, measures of abdominal adiposity such as waist circumference, are generally associated with worse morbidity and mortality in individuals receiving maintenance hemodialysis.

Conclusion

Obesity is a risk factor for the onset and progression of CKD and should be recognized as a potential target for a preventative public health approach to reduce CKD rates within the general population. Future research should focus on the use of glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors in patients with CKD and obesity due to their multi-faceted actions on major outcomes.

Predialysis Urea Nitrogen Is a Nutritional Marker of Hemodialysis Patients

End-stage renal disease (ESRD) patients on hemodialysis have poor nutritional status and associated problems such as inflammation and sarcopenia. Blood urea nitrogen (BUN) is an important measure of uremic toxins, and urea reduction is a marker of hemodialysis efficacy. However, a low protein diet for lower BUN could aggravate malnutrition in patients, and optimal pre-dialysis BUN is not defined. We investigated the association of pre-dialysis BUN with patients' comorbidities and the relationship between pre-dialysis BUN and serum albumin as a nutrient marker. Among the 67 patients, the average pre- and post-dialysis BUN were 59.2 and 15.0 mg/dL, respectively, serum creatinine was 10.1 mg/dL, and the average serum albumin was 4.0 g/dL. Patients' age was negatively correlated with serum creatinine (r=-0.277, p<0.05) and albumin (r=-0.453, p<0.001). Predialysis BUN showed a significant positive correlation with serum albumin (r=0.287, p<0.05) and creatinine (r=0.454, p<0.001). However, the predialysis BUN was not significantly related to diabetes, coronary artery disease, congestive heart failure, or cerebrovascular disease. Hemodialysis patients with high pre-dialysis BUN and high serum creatinine could be regarded as having good nutritional status. The significance of this study lies in the potential utility of pre-dialysis blood urea nitrogen as an indicator of the nutritional status of patients. Liberal protein intake might be recommended to adequately dialyzed patients.

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.

Assessment and management of obesity and metabolic syndrome in children with CKD stages 2-5 on dialysis and after kidney transplantation-clinical practice recommendations from the Pediatric Renal Nutrition Taskforce

Obesity and metabolic syndrome (O&MS) due to the worldwide obesity epidemic affects children at all stages of chronic kidney disease (CKD) including dialysis and after kidney transplantation. The presence of O&MS in the pediatric CKD population may augment the already increased cardiovascular risk and contribute to the loss of kidney function. The Pediatric Renal Nutrition Taskforce (PRNT) is an international team of pediatric renal dietitians and pediatric nephrologists who develop clinical practice recommendations (CPRs) for the nutritional management of children with kidney diseases. We present CPRs for the assessment and management of O&MS in children with CKD stages 2-5, on dialysis and after kidney transplantation. We address the risk factors and diagnostic criteria for O&MS and discuss their management focusing on non-pharmacological treatment management, including diet, physical activity, and behavior modification in the context of age and CKD stage. The statements have been graded using the American Academy of Pediatrics grading matrix. Statements with a low grade or those that are opinion-based must be carefully considered and adapted to individual patient needs based on the clinical judgment of the treating physician and dietitian. Research recommendations are provided. The CPRs will be periodically audited and updated by the PRNT.

Nutritional Status, Nutritional Phenotypes, and Oral Nutritional Supplement Prescription Patterns Among Patients With Non-Dialysis Chronic Kidney Disease in British Columbia

OBJECTIVES

Management of protein-energy wasting and undernutrition with oral nutritional supplements (ONS) has not been systematically studied in the non-dialysis chronic kidney disease (CKD-ND) population. We aimed to describe nutritional status, identify phenotypes of patients prescribed ONS, and evaluate ONS prescription patterns among CKD-ND patients in British Columbia.

DESIGN AND METHODS

This observational study assessed adult CKD-ND patients who entered multidisciplinary CKD clinics during 2013-2018 in British Columbia. Descriptive statistics were used to describe baseline nutrition and inflammation parameters among patients prescribed ONS versus patients not prescribed ONS within 1 year of clinic entry. Hierarchical clustering method with consensus clustering was applied to identify phenotypes of patients prescribed ONS. Multivariable logistic regression was used to assess the associations between ONS prescription and health region/dietitian full-time equivalents per 1,000 CKD patients.

RESULTS

Of 15,859 CKD-ND patients, 9% of patients entering CKD clinics were prescribed ONS within 1 year of clinic entry, and these patients demonstrated lower baseline estimated glomerular filtration rate, body mass index (BMI), serum albumin, bicarbonate, as well as greater age, serum phosphate, and neutrophil-to-lymphocyte ratio compared with those not receiving ONS. Cluster analysis revealed 5 phenotypes of ONS users: cluster 1 had the highest mean neutrophil-to-lymphocyte ratio; cluster 2 had the lowest mean albumin; cluster 3 had the lowest mean BMI; cluster 4 had the highest mean BMI; and cluster 5 had the lowest mean bicarbonate. There was regional variability in ONS prescription, and an odds ratio for ONS prescription of 1.32 (95% confidence interval 1.16-1.50) for every 1-unit increase in dietitian full-time equivalents per 1,000 patients. Over 3 years of follow-up, overall ONS use among CKD-ND patients remained stable.

CONCLUSIONS

This study demonstrates appropriate prescribing of ONS to patients with suboptimal nutritional status, although regional variation exists. Patients receiving ONS represent a heterogenous group with phenotypes reflecting several clinical and biochemical features of the protein-energy wasting syndrome. These findings will assist with updating ONS policy, planning quality improvement initiatives, and informing dietitian resource allocation.

Intradialytic nutrition and quality of life in Chilean older patients in hemodialysis with protein-energy wasting

PURPOSE

The study assessed the impact of intradialytic oral nutritional supplementation on the quality of life in patients receiving hemodialysis and diagnosed with protein energy wasting.

METHODS

A pre-test post-test quasi-experimental study was conducted before and after 3 months of intradialytic oral nutritional supplementation on 109 older hemodialysis patients. We measured before and after 3 months of intradialytic oral nutritional supplementation, the quality of life score, the burden of kidney disease, three quality of life scales and the mental and physical health status using KDQoL-SF™ 1.3, body composition and biochemical parameters of nutritional condition.

RESULTS

The mean age of the patients was 69.4 ± 3.4 years, 59% were male, and the time on dialysis was 63.5 ± 52.6 months. Comparing the baseline with month 3 of intradialytic oral nutritional supplementation, we observed to better quality of life. In contrast to malnutrition, score, specifically increased significantly score of symptoms/problems list related to hemodialysis, sexual function, social and cognitive function, sleep, pain, energy/fatigue and general state of health. Significant changes were also found in nutritional status, energy intake and body composition indicators. After 3 months of intradialytic oral nutritional supplementation, we observed a nutritional status recovery in one or more indicators in 92% of the patients.

CONCLUSION

Our findings indicate that 3 months of intradialysis oral nutritional supplementation improves the components of physical and mental quality of life and nutritional status in older patients receiving hemodialysis diagnosed with loss of protein energy. These results are relevant to improve the experience of patients with protein energy loss receiving hemodialysis.

Effects of hormonal changes on sarcopenia in chronic kidney disease: where are we now and what can we do?

Sarcopenia or muscle wasting is a progressive and generalized skeletal muscle disorder involving the accelerated loss of muscle mass and function, often associated with muscle weakness (dynapenia) and frailty. Whereas primary sarcopenia is related to ageing, secondary sarcopenia happens independent of age in the context of chronic disease states such as chronic kidney disease (CKD). Sarcopenia has become a major focus of research and public policy debate due to its impact on patient's health-related quality of life, health-care expenditure, morbidity, and mortality. The development of sarcopenia in patients with CKD is multifactorial and it may occur independently of weight loss or cachexia including under obese sarcopenia. Hormonal imbalances can facilitate the development of sarcopenia in the general population and is a common finding in CKD. Hormones that may influence the development of sarcopenia are testosterone, growth hormone, insulin, thyroid hormones, and vitamin D. Although the relationship between free testosterone level that is low in uraemic patients and sarcopenia in CKD is not well-defined, functional improvement may be seen. Unlike testosterone, it is known that vitamin D is associated with muscle strength, muscle size, and physical performance in patients with CKD. Outcomes after vitamin D replacement therapy are still controversial. The half-life of growth hormone (GH) is prolonged in patients with CKD. Besides, IGF-1 levels are normal in patients with Stage 4 CKD-a minimal reduction is seen in the end-stage renal disease. Unresponsiveness or resistance of IGF-1 and changes in the GH/IGF-1 axis are the main causes of sarcopenia in CKD. Low serum T3 level is frequent in CKD, but the net effect on sarcopenia is not well-studied. CKD patients develop insulin resistance (IR) from the earliest period even before GFR decline begins. IR reduces glucose utilization as an energy source by hepatic gluconeogenesis, decreasing muscle glucose uptake, impairing intracellular glucose metabolism. This cascade results in muscle protein breakdown. IR and sarcopenia might also be a new pathway for targeting. Ghrelin, oestrogen, cortisol, and dehydroepiandrosterone may be other players in the setting of sarcopenia. In this review, we mainly examine the effects of hormonal changes on the occurrence of sarcopenia in patients with CKD via the available data.

Pectoralis major muscle quantification by cardiac MRI is a strong predictor of major events in HF

Clinical overt cardiac cachexia is a late ominous sign in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF). The main goal of this study was to assess the feasibility and prognostic significance of muscle mass quantification by cardiac magnetic resonance (CMR) in HF with reduced LVEF. HF patients with LVEF < 40% (HFrEF) referred for CMR were retrospectively identified in a single center. Key exclusion criteria were primary muscle disease, known infiltrative myocardial disease and intracardiac devices. Pectoralis major muscles were measured on standard axial images at the level of the 3rd rib anteriorly. Time to all-cause death or HF hospitalization was the primary endpoint. A total of 298 HF patients were included (mean age 64 ± 12 years; 76% male; mean LVEF 30 ± 8%). During a median follow-up of 22 months (IQR: 12-33), 67 (22.5%) patients met the primary endpoint (33 died and 45 had at least 1 HF hospitalization). In multivariate analysis, LVEF [Hazard Ratio (HR): 0.950; 95% Confidence Interval (CI): 0.917-0.983; p = 0.003), NYHA class I-II vs III-IV (HR: 0.480; CI: 0.272-0.842; p = 0.010), creatinine (HR: 2.653; CI: 1.548-4.545; p < 0.001) and pectoralis major area (HR: 0.873; 95% CI: 0.821-0.929; p < 0.001) were independent predictors of the primary endpoint, when adjusted for gender and NT-pro-BNP levels. Pectoralis major size measured by CMR in HFrEF was independently associated with a higher risk of death or HF hospitalization. Further studies to establish appropriate age and gender-adjusted cut-offs of muscle areas are needed to identify high-risk subgroups.

Obesity phenotypes are, in part, associated with physical activity in diabetic hemodialysis patients

PURPOSE

To investigate the prevalence of obesity phenotypes and their association with physical activity levels among diabetic hemodialysis patients.

METHODS

This is a cross-sectional study with 84 diabetic hemodialysis patients (63.5 ± 9.4 years, 54.8% of men). Obesity was diagnosed as high body fat (≥ 40% for male and ≥ 30% for female). Sarcopenic obesity was considered if low skeletal muscle mass (< 20.0 kg for males and < 15.0 kg for females) and obesity were combined. Dynapenic obesity was defined in the presence of low handgrip strength (< 27 kg for males and < 16 kg for females) and obesity. Muscle failure obesity was confirmed in the concomitant presence of obesity, sarcopenia, and dynapenia. Physical activity level was assessed by the Baecke questionnaire and patients were classified as low physical activity according to the first tertile for each of and total domains.

RESULTS

Fifty-four patients (64%) presented obesity. From these, 5 (6%), 19 (23%) and 8 (10%) were classified as sarcopenic obese, dynapenic obese, and muscle failure obese, respectively, and 22 (26%) were only obese. Patients with sarcopenic obesity and muscle failure obesity had lower leisure and locomotion physical activity scores than non-obese, whereas the total domain score did not differ across the groups. Muscle failure obesity was independently associated with low leisure physical activity (OR 10.8, 95% CI 1.3-88.1). Only sarcopenic obesity was independently associated with the locomotion and total physical activity domains (OR 15.4, 95% CI 1.4-90.2 and OR 17.0, 95% CI 1.5-95.4, respectively).

CONCLUSION

Our study found a lower prevalence of sarcopenic obesity compared to dynapenic obesity and muscle failure obesity among diabetic hemodialysis patients. Moreover, sarcopenic obesity and muscle failure obesity, but not dynapenic obesity, were associated with low physical activity levels.

Dialysis of the Obese Patient: Meeting Needs for a Growing Epidemic

Increasing population obesity and associated metabolic consequences has led to increased number of obese patients with chronic kidney disease and end-stage renal disease. While obesity is associated with increased cardiovascular morbidity and mortality, obese dialysis patients present a seeming paradox for survival benefit, given other acute intervening illnesses for those on dialysis with loss of lean body mass overtime. Challenges remain in providing adequate renal replacement options and therapy for this growing segment of obese patients on dialysis which are discussed in this article.

Assessment of the Nutritional Status of the Hemodialysis Patients by Anthropometric Measurements

Objective This study assessed the nutritional status of end-stage renal disease (ESRD) patients on maintenance hemodialysis (MHD) by utilizing bedside anthropometric measurements. Methods This prospective cross-sectional study was done from November 2020 till April 2021 on ESRD patients three times a week MHD at our centre. Anthropometric measurements including body mass index (BMI), triceps skinfold thickness (TSFT), mid-arm circumference (MAC), calf circumference (CC) and handgrip strength (HGS) were measured mid-arm muscle circumference (MAMC) was calculated, and nutritional status was determined. Results Out of 195 patients recruited in our study, 127 (65.1%) were male. The mean age was 51.2 ± 14.8 years with a minimum of 20 and a maximum of 90 years, while the mean duration of HD was 4.6 ± 4.1 years. The majority of our patients had TSFT of 60 % to 90% 93 (47.7%), indicating mild to moderate depletion of fat stores and MAMC of >90 % 128 (65.6%), indicating good protein stores. Among all anthropometric measures, BMI was strongly associated with age (<0.001), while gender and duration of MHD were associated with TSFT (p <0.001). Conclusion Anthropometric measurements are easy and inexpensive bedside methods for assessing the nutritional status of ESRD patients on MHD. Our study concluded that our MHD patients have overall good nutritional status, though our young patients have low BMI and old have obesity. Male patients have weaker HGS. With the increased number of years on MHD, malnutrition increases. Our study will help to treat physicians and nutritionists for proper nutritional planning and implementation to prevent malnutrition.

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.

Association analysis of body composition with survival among prevalent peritoneal dialysis patients

PURPOSE

Progressive decline in lean mass and gain of fat mass are common in patients treated with peritoneal dialysis (PD). It is unclear whether body composition or its longitudinal changes contribute to increased mortality among prevalent PD patients.

METHODS

This was a retrospective cohort study. Body composition was assessed using bioelectrical impedance spectroscopy (BIS). Lean and fat tissue indices were derived from lean and fat mass indexed to height-squared, respectively. The patient's baseline BIS results were used to explore its mortality risk prediction for the entire cohort. Among patients with subsequent BIS measurements, changes of lean and fat mass over time were also examined with survival outcomes.

RESULTS

Among all participants (n = 555, PD vintage 38 months), higher baseline lean tissue index was associated with lower mortality after adjusting for fat tissue index and confounders (HR 0.90; 95% CI 0.84-0.97, p = 0.01). However, this association was no longer significance after the final adjustment with serum albumin level (p = 0.06). A total of 136 patients had repeated BIS data. After the interval of 10.1 months during two consecutive BIS measurements, there was a strong inverse correlation between the percentage changes of lean and fat tissue indices (r = - 0.73, p < 0.001). The longitudinal changes in lean mass, either high or low categories, were not significantly associated with all-cause mortality. In contrast, patients who were classified as having low values of fat tissue index (below median) from baseline to the next BIS measurements had a lower odds of death in the univariable (HR 0.32; 95% CI 0.12-0.84, p = 0.02) but not in the adjusted models.

CONCLUSION

Among prevalent PD patients, higher baseline lean mass was independently associated with better survival. However, the longitudinal changes in lean mass were not significantly associated with mortality. In contrast, the maintenance of low fat status over time appeared to be associated with a lower likelihood of death among PD population.

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.

The effect of different measurement modalities in the association of lean mass with mortality: A systematic review and meta-analysis

OBJECTIVES

Lean mass is commonly measured by 3 modalities, dual energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA), and computerized tomography (CT). CT is considered the most accurate, while lean mass measured by DXA and BIA often consists of non-muscle compartment, and hence considered less accurate when compared with CT. It remains unclear if the association of lean mass with mortality would differ using different measurement modalities.

METHODS

A systematic review and meta-analysis of lean mass and mortality was conducted. The analysis was stratified by different measurement modalities and health conditions. Pooled hazard ratios were estimated using a random effects model.

RESULTS

This meta-analysis included 188 studies with 98 468 participants. Reduced lean mass measured by BIA, DXA, and CT, was associated with increased risk of mortality with a hazard ratio (HR) of 1.35 (95% CI, 1.21-1.49), 1.18 (95% CI, 1.06-1.30), and 1.44 (95% CI, 1.32-1.57), respectively. Similarly, low lean mass defined by BIA-, DXA-, and CT-measurement was associated with increased risk of mortality, with an HR of 1.81 (95% CI, 1.56-2.10), 1.44 (95% CI, 1.29-1.60), and 1.78 (95% CI, 1.64-1.93).

CONCLUSIONS

Reduced and low lean mass were robustly associated with increased mortality in studies using different measurement modalities.

Systematic review and meta-analysis of lean mass and mortality: Rationale and study description

Objectives

Muscle mass is one of the key components in defining sarcopenia and is known to be important for locomotion and body homeostasis. Lean mass is commonly used as a surrogate of muscle mass and has been shown to be associated with increased mortality. However, the relationship of lean mass with mortality may be affected by different clinical conditions, modalities used, cut-off point to define low or normal lean mass, and even types of cancer among cancer patients. Thus, we aim to perform a comprehensive meta-analysis of lean mass with mortality by considering all these factors.

Methods

Systematic search was done in PubMed, Cochrane Library and Embase for articles related to lean mass and mortality. Lean mass measured by dual X-ray absorptiometry, bioelectrical impedance analysis, and computerized tomography were included.

Results

The number of relevant studies has increased continuously since 2002. A total of 188 studies with 98 468 people were included in the meta-analysis. The association of lean mass with mortality was most studied in cancer patients, followed by people with renal diseases, liver diseases, elderly, people with cardiovascular disease, lung diseases, and other diseases. The meta-analysis can be further conducted in subgroups based on measurement modalities, site of measurements, definition of low lean mass adopted, and types of cancer for studies conducted in cancer patients.

Conclusions

This series of meta-analysis provided insight and evidence on the relationship between lean mass and mortality in all directions, which may be useful for further study and guideline development.

Macrophage and adipocyte interaction as a source of inflammation in kidney disease

In obesity, adipose tissue derived inflammation is associated with unfavorable metabolic consequences. Uremic inflammation is prevalent and contributes to detrimental outcomes. However, the contribution of adipose tissue inflammation in uremia has not been characterized. We studied the contribution of adipose tissue to uremic inflammation in-vitro, in-vivo and in human samples. Exposure to uremic serum resulted in activation of inflammatory pathways including NFκB and HIF1, upregulation of inflammatory cytokines/chemokines and catabolism with lipolysis, and lactate production. Also, co-culture of adipocytes with macrophages primed by uremic serum resulted in higher inflammatory cytokine expression than adipocytes exposed only to uremic serum. Adipose tissue of end stage renal disease subjects revealed increased macrophage infiltration compared to controls after BMI stratification. Similarly, mice with kidney disease recapitulated the inflammatory state observed in uremic patients and additionally demonstrated increased peripheral monocytes and inflammatory polarization of adipose tissue macrophages (ATMS). In contrast, adipose tissue in uremic IL-6 knock out mice showed reduced ATMS density compared to uremic wild-type controls. Differences in ATMS density highlight the necessary role of IL-6 in macrophage infiltration in uremia. Uremia promotes changes in adipocytes and macrophages enhancing production of inflammatory cytokines. We demonstrate an interaction between uremic activated macrophages and adipose tissue that augments inflammation in uremia.

Uremic Sarcopenia and Its Possible Nutritional Approach

Uremic sarcopenia is a frequent condition present in chronic kidney disease (CKD) patients and is characterized by reduced muscle mass, muscle strength and physical performance. Uremic sarcopenia is related to an increased risk of hospitalization and all-causes mortality. This pathological condition is caused not only by advanced age but also by others factors typical of CKD patients such as metabolic acidosis, hemodialysis therapy, low-grade inflammatory status and inadequate protein-energy intake. Currently, treatments available to ameliorate uremic sarcopenia include nutritional therapy (oral nutritional supplement, inter/intradialytic parenteral nutrition, enteral nutrition, high protein and fiber diet and percutaneous endoscopic gastrectomy) and a personalized program of physical activity. The aim of this review is to analyze the possible benefits induced by nutritional therapy alone or in combination with a personalized program of physical activity, on onset and/or progression of uremic sarcopenia.

Hopelessness and Depression Predict Sarcopenia in Advanced CKD and Dialysis: A Multicenter Cohort Study

BACKGROUND/OBJECTIVES

Depression and hopelessness are frequently experienced in chronic kidney disease (CKD) and are generally associated with lessened physical activity. The aim of this study was to quantify the associations between sarcopenia as determined by SARC-F with both depression and hopelessness.

DESIGN AND SETTING

This multicenter cohort study involving cross-sectional and longitudinal analyses was conducted in a university hospital and four general hospitals, each with a nephrology center, in Japan.

PARTICIPANTS

Participants consisted of 314 CKD patients (mean age 67.6), some of whom were receiving dialysis (228, 73%).

MEASUREMENTS

The main exposures were depression, measured using the Center for Epidemiologic Studies Depression (CES-D) questionnaire, and hopelessness, measured using a recently developed 18-item health-related hope scale (HR-Hope). The outcomes were sarcopenia at baseline and one year after, measured using the SARC-F questionnaire. Logistic regression models were applied.

RESULTS

The cross-sectional and longitudinal analyses included 314 and 180 patients, respectively. Eighty-nine (28.3%) patients experienced sarcopenia at baseline, and 44 (24.4%) had sarcopenia at the one-year follow-up. More hopelessness (per 10-point lower, adjusted odds ratio [AOR]: 1.33, 95% confidence interval [95% CI] 1.12-1.58), depression (AOR: 1.87, 95% CI 1.003-3.49), age (per 10-year higher, AOR: 1.70, 95% CI 1.29-2.25), being female (AOR: 2.67, 95% CI 1.43-4.98), and undergoing hemodialysis (AOR, 2.92; 95% CI, 1.41-6.05) were associated with a higher likelihood of having baseline sarcopenia. More hopelessness (per 10-point lower, AOR: 1.69, 95% CI 1.14-2.51) and depression (AOR: 4.64, 95% CI: 1.33-16.2) were associated with a higher likelihood of having sarcopenia after one year.

CONCLUSIONS

Among patients with different stages of CKD, both hopelessness and depression predicted sarcopenia. Provision of antidepressant therapies or goal-oriented educational programs to alleviate depression or hopelessness can be useful options to prevent sarcopenia.

Skeletal Muscle Index as a Prognostic Marker for Kidney Transplantation in Older Patients

OBJECTIVE

Low skeletal muscle mass has emerged as a risk factor for mortality after liver transplantation. We evaluated the prognostic value of muscle mass on length of hospitalization and adverse outcomes after kidney transplantation in aging end-stage renal disease patients.

METHODS

One hundred twenty-two patients aged 60 years or older at the time of transplantation were retrospectively analyzed. Skeletal muscle index (SMI), evaluated by computed tomography scan, was calculated from total muscle surface area at L3 vertebral level divided by body height squared. Outcomes were compared according to SMI (namely, length of hospitalization, wound complications, combined endpoint comprising all-cause mortality, and graft failure within 1 year).

RESULTS

In male patients, by multivariate analysis, a low SMI (<42 cm²/m²) was associated with longer immediate post-transplantation hospitalization (β = 17.03 ± 4.3; P = .0002), longer total hospitalization during the first year (β = 34.3 ± 10.7; P = .002), higher rate of wound complications (odds ratio = 12.1 [1.9-77.0]; P = .008), and higher rate of the combined endpoint of graft loss or death (odds ratio = 3.4 [3.0-399.5]; P = .004). In female patients, low SMI was not associated with length of hospitalization or adverse outcomes after transplantation.

CONCLUSION

SMI is an independent marker of morbidity and mortality after kidney transplantation in older men and could help thereby nephrologists better select aging candidates for kidney transplantation with a view to improving post-transplant outcomes.

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.

Double burden of malnutrition in persons with obesity

A paradoxical double challenge has emerged in the last decades with respect to nutrition and nutrition-related clinical conditions. Hunger-related undernutrition continues to represent an unacceptable burden, although its prevalence has been encouragingly reduced worldwide. On the other hand, the prevalence of overweight and obesity, defined as fat excess accumulation with negative impact on individual health, has dramatically increased due to increasingly pervasive obesogenic lifestyle changes. Undernutrition and obesity may coexist in world regions, Countries and even smaller communities and households, being referred to as double burden of malnutrition. It is however important to point out that fat accumulation and obesity may also induce additional nutritional derangements in affected individuals, both directly through metabolic and body composition changes and indirectly through acute and chronic diseases with negative impact on nutritional status. In the current narrative review, associations between fat accumulation in obesity and malnutrition features as well as their known causes will be reviewed and summarized. These include risk of loss of skeletal muscle mass and function (sarcopenia) that may allow for malnutrition diagnosis also in overweight and obese individuals, thereby introducing a new clinically relevant perspective to the obesity-related double burden of malnutrition concept.

Alterations of body composition patterns in pre-dialysis chronic kidney disease patients

PURPOSE

Body mass index (BMI) might be an inaccurate estimate of detailed body composition because it does not differentiate muscle from fat mass. We sought to understand the effect of kidney function decline on alterations of body composition patterns among pre-dialysis CKD patients.

METHODS

Body composition was measured by multi-frequency bioelectrical impedance analysis (BIA). Low muscle mass was defined as appendicular muscle mass (kg) adjusted to the square of height in meters < 7.0 and 5.7 kg/m² in men and women, respectively. The designation of obesity by percent body fat was ≥ 25% in men and ≥ 30% in women. Alternative definition of obesity by BMI was ≥ 25 kg/m². Visceral fat area cut point was > 100 cm² as indication of abdominal obesity.

RESULTS

Mean age of participants was 61.3 ± 13.8 years (n = 103). The average glomerular filtration rate (GFR) was 34.0 ± 24.2 mL/min/1.73 m². By BIA, the prevalence of low muscle mass was 16.5% and was comparable between both sexes. Obesity by percent body fat was identified in 71.8% of patients and 38.2% had abdominal obesity. Using BMI criteria, the prevalence of obesity was less common (55.3%) and associated with under-identification of obesity by 27.0%. Low muscle mass and obesity by percent body fat were more prevalent in the more advanced stages of CKD. By multivariable regression analysis, a 10 mL/min/1.73 m² decline in GFR was associated with a 0.59 kg reduction of total body muscle mass (p = 0.01), but not fat mass or BMI, after adjusting for confounders.

CONCLUSION

Low muscle mass was prevalent among pre-dialysis CKD patients. BMI commonly classified obese CKD individuals by percent body fat criteria as non-obese. The reduction of muscle mass was associated with GFR decline.

Muscle mass assessment in renal disease: the role of imaging techniques

Muscle wasting is a frequent finding in patients with chronic kidney disease (CKD), especially in those with end-stage kidney disease (ESKD) on chronic dialysis. Muscle wasting in CKD is a main feature of malnutrition, and results principally from a vast array of metabolic derangements typical of the syndrome, that converge in determining reduced protein synthesis and accelerated protein catabolism. In this clinical setting, muscle wasting is also frequently associated with disability, frailty, infections, depression, worsened quality of life and increased mortality. On these grounds, the evaluation of nutritional status is crucial for an adequate management of renal patients, and consists of a comprehensive assessment allowing for the identification of malnourished patients and patients at nutritional risk. It is based essentially on the assessment of the extent and trend of body weight loss, as well as of spontaneous dietary intake. Another key component of this evaluation is the determination of body composition, which, depending on the selected method among several ones available, can identify accurately patients with decreased muscle mass. The choice will depend on the availability and ease of application of a specific technique in clinical practice based on local experience, staff resources and good repeatability over time. Surrogate methods, such as anthropometry and bioimpedance analysis (BIA), represent the most readily available techniques. Other methods based on imaging modalities [dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and whole body computed tomography (CT)] are considered to be the "gold standard" reference methods for muscle mass evaluation, but their use is mainly confined to research purposes. New imaging modalities, such as segmental CT scan and muscle ultrasound have been proposed in recent years. Particularly, ultrasound is a promising technique in this field, as it is commonly available for bedside evaluation of renal patients in nephrology wards. However, more data are needed before a routine use of ultrasound for muscle mass evaluation can be recommended in clinical practice.

Uremic Sarcopenia: Clinical Evidence and Basic Experimental Approach

Sustained physical activity extends healthy life years while a lower activity due to sarcopenia can reduce them. Sarcopenia is defined as a decrease in skeletal muscle mass and strength due not only to aging, but also from a variety of debilitating chronic illnesses such as cancer and heart failure. Patients with chronic kidney disease (CKD), who tend to be cachexic and in frail health, may develop uremic sarcopenia or uremic myopathy due to an imbalance between muscle protein synthesis and catabolism. Here, we review clinical evidence indicating reduced physical activity as renal function deteriorates and explore evidence-supported therapeutic options focusing on nutrition and physical training. In addition, although sarcopenia is a clinical concept and difficult to recapitulate in basic research, several in vivo approaches have been attempted, such as rodent subtotal nephrectomy representing both renal dysfunction and muscle weakness. This review highlights molecular mechanisms and promising interventions for uremic sarcopenia that were revealed through basic research. Extensive study is still needed to cast light on the many aspects of locomotive organ impairments in CKD and explore the ways that diet and exercise therapies can improve both outcomes and quality of life at every level.

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.

Effect of a pedometer-based walking intervention on body composition in patients with ESRD: a randomized controlled trial

BACKGROUND

A randomized trial of a pedometer-based intervention with weekly activity goals led to a modest increase in step count among dialysis patients. In a secondary analysis, we investigated the effect of this intervention on body composition.

METHODS

Sixty dialysis patients were randomized to standard care or a 6-month program consisting of 3 months of pedometers and weekly step count targets and 3 months of post-intervention follow-up. We obtained bioelectrical impedance spectroscopy (BIS) data on 54 of these patients (28 control, 26 intervention) and used linear mixed-modeling (adjusted for sex and dialysis modality) to estimate differences in change in total-body muscle mass (TBMM) adjusted for height2, fat mass (kg), and body mass index (BMI) (kg/m2) between control and intervention groups.

RESULTS

The median age of participants was 57.5 years (53-66), and 76% were men. At baseline, there was no significant difference between groups in age, BMI, race, or body composition, but there were more men in the intervention group. After 3 months, patients in the intervention group increased their average daily steps by 2414 (95% CI 1047, 3782) more than controls (p < 0.001), but there were no significant differences in body composition. However, at 6 months, participants in the intervention had a significantly greater increase from baseline in TBMM of 0.7 kg/m2 (95% CI 0.3, 1.13), decrease in fat mass (- 4.3 kg [95% CI -7.1, - 1.5]) and decrease in BMI (- 1.0 kg/m2 [95% CI -1.8, - 0.2]) relative to controls. In post-hoc analysis, each increase of 1000 steps from 0 to 3 months was associated with a 0.3 kg decrease in fat mass (95% CI 0.05, 0.5) from 0 to 6 months, but there was no dose-response relationship with TBMM/ht2 or BMI.

CONCLUSION

A pedometer-based intervention resulted in greater decreases in fat mass with relative preservation of muscle mass, leading to a greater decrease in BMI over time compared with patients not in the intervention. These differences were driven as much by worsening in the control group as by improvement in the intervention group. Step counts had a dose-response relationship with decrease in fat mass.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT02623348). 02 December 2015.

Axial Muscle Size as a Strong Predictor of Death in Subjects With and Without Heart Failure

Background

The impact of skeletal muscle size, quantified using simple noninvasive images routinely obtained during cardiac magnetic resonance imaging studies on mortality in the heart failure (HF) population is currently unknown.

Methods and Results

We prospectively enrolled 567 subjects without HF (n=364), with HF with reduced ejection fraction (n=111), or with HF with preserved ejection fraction (n=92), who underwent a cardiac magnetic resonance imaging. Skeletal muscle cross‐sectional area was assessed with manual tracing of major thoracic muscle groups on axial chest magnetic resonance images. Factor analysis was used to identify a latent factor underlying the shared variability in thoracic muscle cross‐sectional area. Cox regression was used to assess the relationship between these measurements and all‐cause mortality (median follow up, 36.4 months). A higher overall thoracic muscle area factor assessed with principal component analysis was independently associated with lower mortality (standardized hazard ratio, 0.51; P<0.0001). The thoracic muscle area factor was predictive of death in subjects with HF with preserved ejection fraction, HF with reduced ejection fraction, and those without HF. Among all muscle groups, the pectoralis major cross‐sectional area was the most representative of overall muscle area and was also the most robust predictor of death. A higher pectoralis major cross‐sectional area predicted a lower mortality (standardized hazard ratio, 0.49; P<0.0001), which persisted after adjustment for various confounders (standardized hazard ratio, 0.55; P=0.0017).

Conclusions

Axial muscle size, and in particular smaller size of the pectoralis major, is independently associated with higher risk of mortality in patients with and without HF. Further work should clarify the role of muscle wasting as a therapeutic target in patients with HF.

Radiologic Assessment of Muscle and Fat Stores in Long-Term Type I Diabetics Referred for Pancreas Transplant Compared to Healthy Controls

Type 1 diabetes (DM1) is associated with loss of skeletal muscle and bone mass and may affect body fat stores. This study employs computed tomography (CT) scans to assess the body composition of DM1 patients referred for pancreas transplant compared to healthy controls. A 1:1 case-control design matched study patients with otherwise healthy patients from the trauma database. Matching criteria included age ± 5 years, gender, and body mass index (BMI) ± 2kg/m². Nutrition variables included serum albumin and protein levels, BMI, and CT measures of muscle mass and fat stores. There were 22 subjects and 22 controls (median DM1 duration 24 years). DM1 patients had less muscle mass and less subcutaneous fat but no difference in visceral fat. Patients with the greatest muscle deficit were those with DM1 greater than 20 years and those younger than age 40. DM1 patients maintain similar BMI and protein levels compared to healthy controls but have marked deficits of muscle and subcutaneous fat. These results inform the nutritional management of DM1 patients and quantify the muscle and fat deficits present in these patients. At highest risk are young patients and those with duration of DM1 over 20 years.