Skeletal muscle loss is negatively associated with single-pool Kt/V and dialysis duration in hemodialysis patients

Predictors of Skeletal Muscle Index for Patients Treated With Hemodialysis

OBJECTIVE

There is an increased risk of skeletal muscle mass (SMM) loss among patients with stage 5 chronic kidney disease treated with maintenance hemodialysis (MHD). The reduced SMM considerably influences the development of protein-energy wasting (PEW). Patients who develop PEW have higher hospitalization and mortality rates than those without PEW. This study determined if key variables could predict SMM Index (SMM adjusted for height) in patients receiving MHD.

METHODS

We conducted a secondary analysis of cross-sectional data obtained from the Rutgers Nutrition and Kidney Database (n = 178). Data were used to calculate both SMM and SMM Index. Univariate and multiple linear regression models explored the relationship between SMM Index and the following variables: serum albumin, urea clearance normalized treatment ratio, normalized protein catabolic rate, serum creatinine, and urea reduction ratio (URR).

RESULTS

Most participants were Black/African American (82.9%), male (59.1%), and obese (39%), with a mean age of 55.9 ± 11.9 years. The median Subjective Global Assessment score was 5, indicating a lower risk of malnutrition. Participants had a mean SMM of 26.4 kg and a median SMM Index of 8.9 kg/m2. Univariate regression modeling found URR to be a significant predictor of SMM Index, with increases in the percentage of URR predicting lower SMM Index values. The adjusted regression modeling found similar results, with increases in URR percentage predicting declines in SMM Index.

CONCLUSION

This study found that URR was a predictor of SMM Index in patients receiving MHD. Further research is required to explore these relationships and provide clinicians with a more extensive array of tools to recognize early signs of SMM loss to prevent the progression of PEW.

Skeletal muscle atrophy in clinical and preclinical models of chronic kidney disease: A systematic review and meta-analysis

Patients with chronic kidney disease (CKD) are often regarded as experiencing wasting of muscle mass and declining muscle strength and function, collectively termed sarcopenia. The extent of skeletal muscle wasting in clinical and preclinical CKD populations is unclear. We evaluated skeletal muscle atrophy in preclinical and clinical models of CKD, with multiple sub-analyses for muscle mass assessment methods, CKD severity, sex and across the different preclinical models of CKD. We performed a systematic literature review of clinical and preclinical studies that measured muscle mass/size using the following databases: Ovid Medline, Embase and Scopus. A random effects meta-analysis was utilized to determine standard mean difference (SMD; Hedges' g) between healthy and CKD. Heterogeneity was evaluated using the I2 statistic. Preclinical study quality was assessed via the Systematic Review Centre for Laboratory Animal Experimentation and clinical studies quality was assessed via the Newcastle-Ottawa Scale. This study was registered in PROSPERO (CRD42020180737) prior to initiation of the search. A total of 111 studies were included in this analysis using the following subgroups: 106 studies in the primary CKD analysis, 18 studies that accounted for diabetes and 7 kidney transplant studies. Significant atrophy was demonstrated in 78% of the preclinical studies and 49% of the clinical studies. The random effects model demonstrated a medium overall SMD (SMD = 0.58, 95% CI = 0.52-0.64) when combining clinical and preclinical studies, a medium SMD for the clinical population (SMD = 0.48, 95% CI = 0.42-0.55; all stages) and a large SMD for preclinical CKD (SMD = 0.95, 95% CI = 0.76-1.14). Further sub-analyses were performed based upon assessment methods, disease status and animal model. Muscle atrophy was reported in 49% of the clinical studies, paired with small mean differences. Preclinical studies reported significant atrophy in 78% of studies, with large mean differences. Across multiple clinical sub-analyses such as severity of CKD, dialysis modality and diabetes, a medium mean difference was found. Sub-analyses in both clinical and preclinical studies found a large mean difference for males and medium for females suggesting sex-specific implications. Muscle atrophy differences varied based upon assessment method for clinical and preclinical studies. Limitations in study design prevented conclusions to be made about the extent of muscle loss with disease progression, or the impact of dialysis. Future work would benefit from the use of standardized measurement methods and consistent clinical staging to improve our understanding of atrophy changes in CKD progression, and analysis of biological sex differences.

THE RELATIONSHIP BETWEEN MYOSTATIN, INFLAMMATORY MARKERS AND SARCOPENIA IN PATIENTS WITH CHRONIC KIDNEY DISEASE

OBJECTIVE

To determine the prevalence of sarcopenia in patients with chronic kidney disease (CKD), investigate the relationship of the serum myostatin level with sarcopenia and inflammatory markers.

METHODS

The study was conducted with four patient groups: renal transplantation (TX), stage 3-5 non-dialysis-dependent CKD (NDD-CKD), hemodialysis (HD), and peritoneal dialysis (PD). Laboratory parameters, serum myostatin, C-reactive protein, and interleukin-6 ​​(IL-6) levels were studied. Body composition was estimated using a multifrequency bioimpedance analysis. Handgrip strength (HGS) was evaluated with a handgrip dynamometer. The HGS and appendicular skeletal muscle index (ASMI) measurements were used to determine sarcopenia presence.

RESULTS

The study included 130 patients [72(55%) males]. The patient distribution in groups was as follows: 37 in HD, 28 in PD, 37 in renal TX, and 28 in NDD-CKD. The highest level of myostatin was measured in the HD group and the lowest in the TX group (p<0.001). The HGS measurement was significantly lower only in the PD group compared to the TX group (p=0.025). The myostatin was negatively correlated with HGS, albumin, estimated glomerular filtration rate, and Kt/V_urea. However, myostatin had no correlation with inflammatory markers or ASMI. Sarcopenia was present in 37 (29%) of all patients: 15 (40%) in the HD group, nine (32%) in NDD-CKD, seven (25%) in PD, and six (16%) in TX. When the patients with and without sarcopenia were compared, only myostatin was higher in the former (p=0.045). As a result of multivariate analysis, myostatin was the only independent factor which predict sarcopenia (OR: 1.002, 95% CI:1.001-1.005, p=0.048).

CONCLUSION

To prevent devastating events associated with sarcopenia in patients with CKD, renal transplantation seems to be the best treatment solution. For the early recognition of sarcopenia, the measurement of the serum myostatin level may be a promising diagnostic approach.

Creatinine generation rate can detect sarcopenia in patients with hemodialysis

BACKGROUND

Sarcopenia is strongly associated with long-term mortality in patients undergoing hemodialysis. The diagnostic modalities used to assess muscle mass, such as bioimpedance analysis and dual-energy X-ray absorption measurement, have limitations for application in patients on hemodialysis. Therefore, there is a need to establish a simple index for assessing muscle mass that can be universally performed in patients on hemodialysis.

METHODS

Patients on maintenance hemodialysis were included in this study. Laboratory tests, skeletal muscle mass measured by bioimpedance analysis, and clinical records were obtained retrospectively. The creatinine generation rate (CGR) was calculated from the pre- and postdialysis blood tests using a kinetic model as the index for whole-body muscle mass. Correlations between the CGR and skeletal muscle mass were investigated, and the cut-off value for muscle wasting was determined. Kaplan-Meier survival analysis was performed to investigate the feasibility of the CGR for predicting long-term survival.

RESULTS

Among the 130 patients included, eight were diagnosed with sarcopenia by bioimpedance analysis. The CGR was positively correlated with skeletal muscle mass (r = 0.454, p < 0.001). Multiple linear regression analysis revealed that age and sex independently influenced the CGR. The patients were classified into two groups according to age- and sex-adjusted CGRs. During a median follow-up period of 32 months, the Kaplan-Meier survival analysis showed that patients with low CGR showed significantly poor long-term prognosis (p = 0.002).

CONCLUSION

The CGR is a simple index for muscle mass and can predict long-term mortality in patients on hemodialysis.

Handgrip strength as an instrument for assessing the risk of malnutrition and inflammation in hemodialysis patients

INDRODUCTION

Establishing which parameters to use for diagnosing malnutrition in hemodialysis patients is a challenge in clinical practice. The handgrip strength (HGS) has stood out as a method of assessing nutritional status. Thus, the aim of this study was to determine the cut-off point for HGS in the assessment of the risk of malnutrition and inflammation in HD patients, and its association with other parameters.

METHODS

Study carried out in hemodialysis units in the city of Curitiba, Brazil. We obtained the cut-off point of the HGS through the ROC curve, using the malnutrition and inflammation score (MIS) as a reference. We checked the relationship (Odds ratio) between the variables "MIS" and "HGS" with the other study variables using the multivariate analysis (logistic regression).

RESULTS

We assessed 238 patients (132 men), between 18 and 87 years of age (median = 59). The HGS cut-off point for diagnosing malnutrition and inflammation according to the reference used was <14.5 kg for women, and <23.5 kg for men. According to the HGS criteria, malnourished patients were older (OR = 0.958), with lower arm circumference (OR = 1.328) and higher scores in the malnutrition and inflammation score (OR = 0.85).

CONCLUSION

HGS was significantly correlated with other nutritional assessment parameters. These results suggest that HGS is a valid screening tool to identify the risk of malnutrition and inflammation in hemodialysis patients.

Relationship between maximal incremental and high-intensity interval exercise performance in elite athletes

This descriptive study aimed to explore the physiological factors that determine tolerance to exertion during high-intensity interval effort. Forty-seven young women (15–28 years old) were enrolled: 23 athletes from Taiwan national or national reserve teams and 24 moderately active females. Each participant underwent a maximal incremental INC (modified Bruce protocol) cardiopulmonary exercise test on the first day and high-intensity interval testing (HIIT) on the second day, both performed on a treadmill. The HIIT protocol involved alternation between 1-min effort at 120% of the maximal speed, at the same slope reached at the end of the INC, and 1-min rest until volitional exhaustion. Gas exchange, heart rate (HR), and muscle oxygenation at the right vastus lateralis, measured by near-infrared spectroscopy, were continuously recorded. The number of repetitions completed (R_lim) by each participant was considered the HIIT tolerance index. The results showed a large difference in the R_lim (range, 2.6–12.0 repetitions) among the participants. Stepwise linear regression revealed that the variance in the R_lim within the cohort was related to the recovery rates of oxygen consumption (V˙O2), HR at the second minute after INC, and muscle tissue saturation index at exhaustion (R = 0.644). In addition, age was linearly correlated with R_lim (adjusted R = −0.518, p < 0.0001). In conclusion, the recovery rates for V˙O2 and HR after the incremental test, and muscle saturation index at exhaustion, were the major physiological factors related to HIIT performance. These findings provide insights into the role of the recovery phase after maximal INC exercise testing. Future research investigating a combination of INC and HIIT testing to determine training-induced performance improvement is warranted.

Hyperhomocysteinemia Associated with Low Muscle Mass, Muscle Function in Elderly Hemodialysis Patients: An Analysis of Multiple Dialysis Centers

Background

The hyperhomocysteinemia was with high prevalence and has been considered as a risk factor for cardiovascular disease in hemodialysis patients. These patients also experienced a high risk of muscle wasting caused by the comorbidity, malnutrition, and low physical activity. We investigated the associations of homocysteinemia with muscle mass, muscle function in elderly hemodialysis patients.

Methods

A clinical cross-sectional study was conducted on 138 hemodialysis patients aged 65 years and above in seven hospital-based hemodialysis centers in Taiwan. The data on anthropometry, laboratory, and 3-day dietary intake was examined. The skeletal muscle mass (SMM) was measured by the bioelectrical impedance analysis; the SMM was adjusted by height or weight as SMM_Ht2 (kg/m²) and SMM_Wt (%). Muscle function was defined as handgrip strength (HGS) (kg) measured by handgrip dynamometer. Statistical analyses were conducted using simple regression and multivariable stepwise regression analysis.

Results

In the total sample, 74.6 % of hemodialysis patients were hyperhomocysteinemia (≥ 15 μmol/L). The means of SMM_Ht2, SMM_Wt, arm lean mass, hand grip strength, and muscle quality were 8.7 ± 1.2, 37.7 ± 5.6, 1.7 ± 0.5, 21.1 ± 7.4, and 10.0 ± 3.0, respectively. The multivariable stepwise regression analysis showed that homocysteinemia level was significantly inversely associated with SMM_Wt (B-coeff. = -0.03, p = 0.02) in hemodialysis patients above 65 years old, but not with muscle function.

Conclusions

Hyperhomocysteinemia is common and associated with decreased muscle mass in the elderly hemodialysis patients. Future studies are suggested to explore the impact of the homocysteine-lowering therapy on muscle decline.

Physical inactivity and protein energy wasting play independent roles in muscle weakness in maintenance haemodialysis patients

Background

Muscle weakness is associated with increased mortality risk in chronic haemodialysis (CHD) patients. Protein energy wasting (PEW) and low physical activity could impair muscle quality and contribute to muscle weakness beyond muscle wasting in these patients. Aim of this study was to assess clinical and biological parameters involved in the reduction of muscle strength of CHD patients.

Methods

One hundred and twenty-three CHD patients (80 males, 43 females; 68,8 [57.9–78.8] y.o.) were included in this study. Maximal voluntary force (MVF) of quadriceps was assessed using a belt-stabilized hand-held dynamometer. Muscle quality was evaluated by muscle specific torque, defined as the strength per unit of muscle mass. Muscle mass was estimated using lean tissue index (LTI), skeletal muscle mass (SMM) assessed by bioelectrical impedance analysis and creatinine index (CI). Voorrips questionnaire was used to estimate physical activity. Criteria for the diagnosis of PEW were serum albumin, body mass index < 23 kg/m², creatinine index < 18.82 mg/kg/d and low dietary protein intake estimated by nPCR < 0.80g/kg/d.

Results

MVF was 76.1 [58.2–111.7] N.m. and was associated with CI (β = 5.3 [2.2–8.4], p = 0.001), LTI (β = 2.8 [0.6–5.1], p = 0.013), Voorrips score (β = 17.4 [2.9–31.9], p = 0.02) and serum albumin (β = 1.9 [0.5–3.2], p = 0.006). Only serum albumin (β = 0.09 [0.03–0.15], p = 0.003), Voorrips score (β = 0.8 [0.2–1.5], p = 0.005) and CI (β = 0.2 [0.1–0.3], p<0.001) remained associated with muscle specific torque. Thirty patients have dynapenia defined as impaired MVF with maintained SMM and were younger with high hs-CRP (p = 0.001), PEW criteria (p<0.001) and low Voorrips score (p = 0.001), and reduced dialysis vintage (p<0.046).

Conclusions

Beyond atrophy, physical inactivity and PEW conspire to impair muscle strength and specific torque in CHD patients and could be related to muscle quality.

Trial registration

ClinicalTrials.gov NCT02806089

Decreased serum fatty acid binding protein 4 concentrations are associated with sarcopenia in chronic hemodialysis patients

BACKGROUND

Fatty acid binding protein 4 (FABP4) is found to play a role in skeletal muscle homeostasis. Since the dysregulation of FABP4 and sarcopenia are both highly prevalent in patients on chronic hemodialysis (HD), the correlation between them remains unknown. We aimed to examine this relationship in a cross-sectional study.

METHODS

A total of 120 chronic HD patients were recruited, and whose skeletal muscle mass, handgrip strength, and gait speed were assessed and blood samples were obtained. We grouped these participants into sarcopenia (n = 20) and non-sarcopenia groups according to European Working Group on Sarcopenia in Older People criteria.

RESULTS

The sarcopenia group exhibited lower weight (P < 0.001), height (P = 0.019), waist circumference (P < 0.001), body mass index (P < 0.001), body fat mass (P = 0.004), and lower serum triglycerides (P = 0.009), creatinine (P < 0.001), phosphorus (P = 0.013), intact parathyroid hormone (P = 0.012), and FABP4 concentrations (P = 0.005), and higher malnutrition-inflammation scores (MIS) (P = 0.031), urea reduction rates (P < 0.001), and fractional clearance index for urea (Kt/V) values (P < 0.001). Serum FABP4 concentrations (odds ratio (OR): 0.98, 95% confidence interval (CI): 0.96-0.99, P = 0.043), body fat mass (OR: 0.86, 95% CI: 0.77-0.97, P = 0.013), MIS (OR: 6.90, 95% CI: 1.31-36.36, P = 0.023), and Kt/V (each increase of 0.1, OR: 2.15, 95% CI: 1.29-3.57, P = 0.003) were independent predictors of sarcopenia in chronic HD patients.

CONCLUSIONS

We delineated the association between serum FABP4 concentrations and sarcopenia in chronic HD patients.

Sarcopenia and Physical Inactivity in Patients With Chronic Kidney Disease

Sarcopenia and physical inactivity synergistically progress in patients with chronic kidney disease (CKD) and are strong predictors of mortality in this population. Exercise training and essential amino acids and vitamin D supplements may contribute to improving sarcopenia and physical inactivity in CKD patients.

Ratio of dietary ω-3 and ω-6 fatty acids-independent determinants of muscle mass-in hemodialysis patients with diabetes

OBJECTIVE

ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) are essential nutrients in the human diet and possibly affect muscle mass. We evaluated the association between the dietary ratios of ω-3 and ω-6 PUFAs and muscle mass, indicated as skeletal muscle mass (SMM) and appendicular skeletal muscle mass (ASM), in patients with diabetes undergoing hemodialysis (HD).

METHODS

In this cross-sectional study, data on 69 patients with diabetes who underwent standard HD therapy were analyzed. For estimating muscle mass, anthropometric and bioelectrical impedance analyses were conducted following dialysis. In addition, routine laboratory and 3-d dietary data were obtained. The adequate intake (AI) cut-off for ω-3 PUFAs was 1.6 g/d and 1.1 g/d for male and female patients, respectively.

RESULTS

The average age of the participants was 63.0 ± 10.4 y. The mean ratios of ω-3/ω-6 PUFA intake, ω-6/ω-3 PUFA intake, SMM, and ASM of the patients were 0.13 ± 0.07, 9.4 ± 6.4, 24.6 ± 5.4 kg, and 18.3 ± 4.6 kg, respectively. Patients who had AI of ω-3 PUFAs had significantly higher SMM and ASM than did their counterparts. Linear and stepwise multivariable adjustment analyses revealed that insulin resistance and the ω-6/ω-3 PUFA ratio were the independent deleterious determinants of ASM normalized to height in HD patients.

CONCLUSIONS

Patients with AI of ω-3 PUFAs had total-body SMM and ASM that were more appropriate. A higher dietary ratio of ω-6/ω-3 PUFAs was associated with reduced muscle mass in HD patients.

Isolated Effects of Renal Failure, Anthropometric Indices, and Serum Total Iron-Binding Capacity as Determinants of Muscle Performance in Hemodialysis Patients

OBJECTIVE

We quantified the isolated impact of end-stage renal disease (ESRD) on physical performance under contemporary hemodialysis treatment independent of comorbid diseases, characterized principal anthropometric components, and adjusted for their influence and compared associations of C-reactive protein (CRP), albumin, and serum total iron-binding capacity (TIBC) with muscle function.

DESIGN

A case-control cross-sectional study.

SETTING

University medical hospital and outpatient hemodialysis units.

SUBJECTS

Ninety prevalent hemodialysis patients without important comorbidities and 140 controls.

MAIN OUTCOME MEASURES

Handgrip strength (HGS) and 10-repetition sit-to-stand time (STS-10).

RESULTS

Principal component analysis revealed 3 representative anthropometric measures to be included in explanatory models of muscle performance additional to body height: lean body mass, fat mass, and joint size. Controlling for these covariates, age, sex, and residual comorbidity, ESRD was associated with a modest 7.5% reduction in HGS (B = -2.57 kg; 95% confidence interval: -4.81 to -0.39; P = .005; model R(2) 0.74) and a relatively larger prolongation of 27% in STS-10 time (B = 4s; 95% confidence interval: 2.61 to 5.4; P < .001; model R(2) 0.53). Lean body mass and height significantly predicted both tests, fat mass, and wrist size predicted HGS. In the subgroup of dialysis patients, only TIBC showed a significant association with HGS independently from age, sex, wrist size, whereas CRP and albumin did not. STS-10 time was not associated with any of these biomarkers. Results remained stable in sensitivity analyses excluding patients with reported chronic regional motor difficulties and aches.

CONCLUSIONS

ESRD with contemporary hemodialysis therapy has a relatively modest negative comorbidity-free association with HGS and a larger effect on STS-10 lower extremity performance. Nonmodifiable anthropometric indices (body height and for HGS wrist size) have a significant independent impact and should be consistently adjusted for in future studies. In low-comorbidity dialysis patients, TIBC is a superior predictor of HGS compared with albumin and CRP.

Dual Impact of Tolvaptan on Intracellular and Extracellular Water in Chronic Kidney Disease Patients with Fluid Retention

Objective Tolvaptan, an oral selective V2-receptor antagonist, is a water diuretic that ameliorates fluid retention with a lower risk of a worsening renal function than conventional loop diuretics. Although loop diuretics predominantly decrease extracellular water (ECW) compared with intracellular water (ICW), the effect of tolvaptan on fluid distribution remains unclear. We therefore examined how tolvaptan changes ICW and ECW in accordance with the renal function. Methods Six advanced chronic kidney disease patients (stage 4 or 5) with fluid retention were enrolled in this study. Tolvaptan (7.5 mg/day) added to conventional diuretic treatment was administered to remove fluid retention. The fluid volume was measured using a bioimpedance analysis device before (day 0) and after (day 5 or 6) tolvaptan treatment. Results Body weight decreased by 2.6%±1.3% (64.4±6.5 vs. 62.8±6.3 kg, p=0.06), and urine volume increased by 54.8%±23.9% (1,215±169 vs. 1,709±137 mL/day, p=0.03) between before and after tolvaptan treatment. Tolvaptan significantly decreased ICW (6.5%±1.5%, p=0.01) and ECW (7.5%±1.4%, p=0.02), which had similar reduction rates (p=0.32). The estimated glomerular filtration rate remained unchanged during the treatment (14.6±2.8 vs. 14.9±2.7 mL/min/1.73² m, p=0.35). Conclusion Tolvaptan ameliorates body fluid retention, and induces an equivalent reduction rate of ICW and ECW without a worsening renal function. Tolvaptan is a novel water diuretic that has a different effect on fluid distribution compared with conventional loop diuretics.

Ratio of Dietary n-6/n-3 Polyunsaturated Fatty Acids Independently Related to Muscle Mass Decline in Hemodialysis Patients

Background

n-3 polyunsaturated fatty acids (PUFAs) might be useful nutritional strategy for treating patients with sarcopenia. We evaluated the effect of the intake of dietary n-3 PUFAs on the skeletal muscle mass (SMM), appendicular skeletal muscle mass (ASM), and its determinants in patients receiving standard hemodialysis (HD) treatment for the management of end stage renal disease.

Methods

In this cross-sectional study, data of 111 HD patients were analyzed. Anthropometric and bioelectrical impedance measurements used to estimate the muscle mass were performed the day of dialysis immediately after the dialysis session. Routine laboratory and 3-day dietary data were also collected. The cutoff value of adequate intake (AI) for both n-3 PUFAs and alpha-linolenic acid (ALA) was 1.6 g/day and 1.1 g/day for men and women, respectively.

Results

The mean age, mean dietary n-3 PUFAs intake, ALA intake, ratio of n-6/n-3 PUFAs intake, SMM, and ASM of patients were 61.4 ± 10.4 years, 2.0 ± 1.3 g/day, 1.5 ± 1.0 g/day, 9.5 ± 6.7 g/day, 23.9 ± 5.5 kg, and 17.5 ± 4.5 kg, respectively. A higher SMM and ASM significantly observed in patients who achieved an AI of n-3 PUFAs. Similar trends appeared to be observed among those patients who achieved the AI of ALA, but the difference was not significantly, except for ASM (P = 0.047). No relevant differences in demographics, laboratory and nutritional parameters were observed, regardless of whether the patients achieved an AI of n-3 PUFAs. Multivariate analysis showed that the BMI and equilibrated Kt/V were independent determinants of the muscle mass. Moreover, the ratio of n-6/n-3 PUFAs was an independent risk determinant of reduced ASM in HD patients.

Conclusion

Patients with an AI of n-3 PUFAs had better total-body SMM and ASM. A higher dietary ratio of n-6/n-3 PUFAs seemed to be associated with a reduced muscle mass in HD patients.

Strategies to improve physical activity by exercise training in patients with chronic kidney disease

Decreased physical activity resulting in muscle loss is often observed in patients with chronic kidney disease and is one of the main predictors of mortality in these patients. Exercise training may improve physical activity and prevent muscle loss in patients with chronic kidney disease. Efforts to introduce exercise training to these patients may be clinically beneficial by reducing their mortality rates.