Correlates of Physical Functioning and Performance Across the Spectrum of Kidney Function

Hemodynamic and neuromuscular basis of reduced exercise capacity in patients with end-stage renal disease

PURPOSE

The present study aimed to characterize the exercise-induced neuromuscular fatigue and its possible links with cerebral and muscular oxygen supply and utilization to provide mechanistic insights into the reduced exercise capacity characterizing patients with end-stage renal disease (ESRD).

METHODS

Thirteen patients with ESRD and thirteen healthy males (CTR group) performed a constant-force sustained isometric contraction at 50% of their maximal voluntary isometric contraction (MVC) until exhaustion. Quadriceps muscle activation during exercise was estimated from vastus lateralis, vastus medialis, and rectus femoris EMG. Central and peripheral fatigue were quantified via changes in pre- to postexercise quadriceps voluntary activation (ΔVA) and quadriceps twitch force (ΔQtw,pot) evoked by supramaximal electrical stimulation, respectively. To assess cerebral and muscular oxygenation, throughout exercise, near-infrared spectroscopy allowed investigation of changes in oxyhemoglobin (∆O2Hb), deoxyhemoglobin (∆HHb), and total hemoglobin (∆THb) in the prefrontal cortex and in the vastus lateralis muscle.

RESULTS

ESRD patients demonstrated lower exercise time to exhaustion than that of CTR (88.8 ± 15.3 s and 119.9 ± 14.6 s, respectively, P < 0.01). Following the exercise, MVC, Qtw,pot, and VA reduction were similar between the groups (P > 0.05). There was no significant difference in muscle oxygenation (∆O2Hb) between the two groups (P > 0.05). Cerebral and muscular blood volume (∆THb) and oxygen extraction (∆HHb) were significantly blunted in the ESRD group (P < 0.05). A significant positive correlation was observed between time to exhaustion and cerebral blood volume (∆THb) in both groups (r2 = 0.64, P < 0.01).

CONCLUSIONS

These findings support cerebral hypoperfusion as a factor contributing to the reduction in exercise capacity characterizing ESRD patients.

Skeletal Muscle Injury in Chronic Kidney Disease-From Histologic Changes to Molecular Mechanisms and to Novel Therapies

Chronic kidney disease (CKD) is associated with significant reductions in lean body mass and in the mass of various tissues, including skeletal muscle, which causes fatigue and contributes to high mortality rates. In CKD, the cellular protein turnover is imbalanced, with protein degradation outweighing protein synthesis, leading to a loss of protein and cell mass, which impairs tissue function. As CKD itself, skeletal muscle wasting, or sarcopenia, can have various origins and causes, and both CKD and sarcopenia share common risk factors, such as diabetes, obesity, and age. While these pathologies together with reduced physical performance and malnutrition contribute to muscle loss, they cannot explain all features of CKD-associated sarcopenia. Metabolic acidosis, systemic inflammation, insulin resistance and the accumulation of uremic toxins have been identified as additional factors that occur in CKD and that can contribute to sarcopenia. Here, we discuss the elevation of systemic phosphate levels, also called hyperphosphatemia, and the imbalance in the endocrine regulators of phosphate metabolism as another CKD-associated pathology that can directly and indirectly harm skeletal muscle tissue. To identify causes, affected cell types, and the mechanisms of sarcopenia and thereby novel targets for therapeutic interventions, it is important to first characterize the precise pathologic changes on molecular, cellular, and histologic levels, and to do so in CKD patients as well as in animal models of CKD, which we describe here in detail. We also discuss the currently known pathomechanisms and therapeutic approaches of CKD-associated sarcopenia, as well as the effects of hyperphosphatemia and the novel drug targets it could provide to protect skeletal muscle in CKD.

Physical activity, exercise habits and health-related quality of life in maintenance hemodialysis patients: a multicenter cross-sectional study

BACKGROUND

Although exercise has the potential to yield numerous benefits for maintenance hemodialysis patients, the relationship between physical activity, exercise habits, and health-related quality of life (HRQOL) has not been thoroughly investigated. This study aimed to characterize the physical activity, exercise habits, and HRQOL of maintenance hemodialysis patients while examining the associations between these factors.

METHODS

A convenience sampling was used to recruit 827 patients from 74 dialysis units in China. The structured questionnaire included sociodemographics, the International Physical Activity Questionnaire, exercise habits, and the Kidney Disease Quality of Life Short Form 1.3. An independent samples t-test, multivariable logistic regression analysis, and multivariable linear regression analysis were used.

RESULTS

The physical activity levels of 69% of participants were found to be below the recommendation of the World Health Organization. Despite 62.4% of participants reporting regular exercise, 73.8% reported light exercise intensity, and 92.6% engaged in walking or jogging. Participants' HRQOL was higher in the low-intensity exercise group compared with the moderate-to-hard-intensity exercise group. Moderate-to-high physical activity was associated with better HRQOL in 13 of the 19 domains and regular exercise was linked to higher HRQOL in four of the 19 domains.

CONCLUSIONS

This study identified a low level of physical activity, light exercise intensity, and walking as the primary exercise type among the participants. A significant correlation was found between higher physical activity levels, regular exercise, and better HRQOL for maintenance hemodialysis patients. It is advisable to implement strategies to enhance physical activity levels and design exercise programs for maintenance hemodialysis patients based on their real-world physical activity levels and exercise habits.

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.

Effect of Anemia on Physical Function and Physical Activity in CKD: The National Health and Nutrition Examination Survey, 1999-2016

Key Points

In a large sample representative of the US adult noninstitutionalized population, among participants with CKD stages 3–5, anemia was associated with a significantly lower level of physical activity. The presence of CKD and anemia showed a positive interaction on physical functioning outcomes. Among participants with CKD, physical functioning was worse in patients with anemia compared with those without anemia.

Background

CKD is a major public health problem worldwide. Anemia, a frequent and treatable complication of CKD, is associated with decreased physical functioning and physical activity. The objective of this study was to evaluate the joint association of CKD and anemia with physical functioning and physical activity in a representative sample of the US population.

Methods

Cross-sectional study using the National Health and Nutrition Examination Survey (NHANES) 1999–2016 for physical functioning outcomes (N =33,300) and NHANES 2007–2016 for physical activity (N =22,933). The NHANES physical functioning questionnaire included 19 items. The NHANES physical activity questionnaire captured work-related, leisure-time, and sedentary activities. Higher physical functioning scores represent worse function. CKD was classified using Kidney Disease Outcomes Quality Initiative 2002 criteria, and anemia was defined using the World Health Organization criteria.

Results

The adjusted mean differences (95% confidence interval) in overall physical functioning score comparing participants with anemia with those without anemia among participants with no CKD, CKD stages 1–2, and stages 3–5 were 0.5 (−0.1 to 1.0), 1.5 (0.2 to 2.8), and 3.6 (2.0 to 5.2). Anemia and CKD showed a supra-additive interaction for all physical functioning outcomes among participants in CKD stages 3–5. The prevalence of high physical activity was also lower in participants with anemia compared with those without anemia among participants in CKD stages 3–5 (adjusted prevalence ratio, 0.74; 95% confidence interval, 0.54 to 1.01).

Conclusions

CKD and anemia were associated with impairments in physical functioning and reduced physical activity. For physical functioning outcomes, the combined presence of CKD and of anemia showed a stronger effect than what was expected from their independent effects.

Muscle fat infiltration in chronic kidney disease: a marker related to muscle quality, muscle strength and sarcopenia

Muscle fat infiltration (MFI) also known as myosteatosis refers to any deposit of lipids found in the skeletal muscle. MFI is preferably assessed by image-based methods like computed tomography (CT), magnetic resonance image (MRI) and ultrasound, normally from muscle groups located in the legs, arms and in the trunk. MFI is understood as a marker of muscle quality, where a muscle with higher fat deposition has lower contraction power and capacity to produce force per unit of muscle mass. This concept supports the hypothesis that a decrease in muscle strength is not always explained by a decrease in muscle mass, but also by other factors, including lipid deposition in the muscle. In the general population, MFI is associated with older age, physical inactivity and with insulin resistance and inflammation. In chronic kidney disease (CKD), MFI has been associated with a decrease in muscle strength and impaired muscle quality as well as with metabolic abnormalities, cardiovascular disease and increased mortality. Interventions aimed at reducing MFI in CKD are incipient, but it seems that guided exercise can ameliorate muscle quality in patients on hemodialysis. The aim of this narrative review about MFI in CKD is to draw attention to a still not often addressed complication in CKD. We conclude that more studies are warranted to investigate mechanisms and factors promoting MFI in CKD. Thus, clinical trials aimed at understanding the type, frequency and intensity of exercise that can diminish MFI and improve the clinical condition of the patients are needed.

The Potential Modulatory Effects of Exercise on Skeletal Muscle Redox Status in Chronic Kidney Disease

Chronic Kidney Disease (CKD) is a global health burden with high mortality and health costs. CKD patients exhibit lower cardiorespiratory and muscular fitness, strongly associated with morbidity/mortality, which is exacerbated when they reach the need for renal replacement therapies (RRT). Muscle wasting in CKD has been associated with an inflammatory/oxidative status affecting the resident cells' microenvironment, decreasing repair capacity and leading to atrophy. Exercise may help counteracting such effects; however, the molecular mechanisms remain uncertain. Thus, trying to pinpoint and understand these mechanisms is of particular interest. This review will start with a general background about myogenesis, followed by an overview of the impact of redox imbalance as a mechanism of muscle wasting in CKD, with focus on the modulatory effect of exercise on the skeletal muscle microenvironment.

Association Between Protocols of the Sit-to-Stand Test and Lower Limb Muscle Force Output in Patients on Hemodialysis and Subjects Without Chronic Kidney Disease

OBJECTIVE

To evaluate the association of three protocols of the sit-to-stand (STS) test with muscle force output of knee extension (KE) and knee flexion (KF) in patients on hemodialysis and subjects without chronic kidney disease.

METHODS

This cross-sectional study included a hemodialysis group [n = 60, 59.5 (16.8) years, 55% female] and a control group [n = 60, 43.0 (11.8) years, 50% female]. The assessments were performed in 2 days, and the participants were submitted to three protocols of STS test (5-repetition STS, 10-repetition STS and 30-s STS) or muscle force output of the KE and KF evaluation by handheld dynamometer based on randomization.

RESULTS

The hemodialysis group presented reduced muscle force output of the KE and KF, a longer time to perform the 5 STS and 10 STS tests, and a lower number of repetitions in the 30-s STS test. The three STS tests were associated with muscle force output of the KE in the hemodialysis group, in which the 10-repetition STS test showed the best association (R² = 0.47; adjusted R² = 0.42). However, the only association between the STS test and muscle force output of the KE in the control group was found in the 10-repetition STS test (R² = 0.20; adjusted R² = 0.13).

CONCLUSIONS

The three protocols of STS tests were associated with muscle force output of the KE in patients on hemodialysis. However, the 10-repetition STS test was the best protocol to estimate the quadriceps muscle torque in these patients.

Glittre activities of daily living test is reliable and valid in hemodialysis patients

PURPOSE

To examine the validity, and the relative and absolute within-day reliability of the TGlittre in chronic kidney disease patients undergoing hemodialysis (HD).

MATERIALS AND METHODS

Thirty HD patients (52 ± 12 years) undertook the TGlittre twice on a single day, in a cross-sectional design. For validation purposes, participants TGlittre performance and accelerometry-based physical activity were correlated. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were determined to assess within-day reliability.

RESULTS

There was a moderate correlation between TGlittre performance and moderate to vigorous physical activity (r= -0.587; p= 0.001). The relative reliability of the test showed an ICC of 0.96. For the absolute reliability, the SEM was 13.05 s (0.22 min), and the MDC was 36.17 s (0.60 min).

CONCLUSIONS

TGlittre performance is associated with moderate to vigorous physical activity in HD patients, highlighting that those with higher levels of physical activity are likely to perform better on the TGlittre. Additionally, TGlittre shows a good to excellent intra-rater reliability and a low SEM. An MDC value was established.Implications for rehabilitationPatients on hemodialysis have a low physical capacity and often struggle to simply complete their physical activities of daily living.The TGlittre is a tool for assessing functional capacity through completion of multiple physical activities of daily living and can be easily applied in a clinical setting.TGlittre is a valid test that elicit reliable physiological, hemodynamic, and physical performance responses in HD patients.

Crosstalk between bone and muscle in chronic kidney disease

With increasing life expectancy, the related disorders of bone loss, metabolic dysregulation and sarcopenia have become major health threats to the elderly. Each of these conditions is prevalent in patients with chronic kidney disease (CKD), particularly in more advanced stages. Our current understanding of the bone-muscle interaction is beyond mechanical coupling, where bone and muscle have been identified as interrelated secretory organs, and regulation of both bone and muscle metabolism occurs through osteokines and myokines via autocrine, paracrine and endocrine systems. This review appraises the current knowledge regarding biochemical crosstalk between bone and muscle, and considers recent progress related to the role of osteokines and myokines in CKD, including modulatory effects of physical exercise and potential therapeutic targets to improve musculoskeletal health in CKD patients.

Hemodynamic Tolerance of Virtual Reality Intradialysis Exercise Performed during the Last 30 Minutes versus the Beginning of the Hemodialysis Session

Background: Exercise improves the physical function of people suffering from chronic kidney disease on hemodialysis (HD). Virtual reality is a new type of intradialysis exercise that has a positive impact on physical function. Intradialysis exercise is recommended during the first 2 h, but its safety in the last part of the dialysis session is unknown. Methods: This was a pilot sub-study of a clinical trial. Several hemodynamic control variables were recorded, including blood pressure, heart rate, and intradialytic hypotensive events. These variables were recorded during three different HD sessions, one HD session at rest, another HD session with exercise during the first two hours, and one HD session with exercise during the last 30 min of dialysis. The intradialysis virtual reality exercise was performed for a maximum of 30 min. Results: During exercise sessions, there was a significant increase in heart rate (6.65 (4.92, 8.39) bpm; p < 0.001) and systolic blood pressure (6.25 (0.04,12.47) mmHg; p < 0.05). There was no difference in hemodynamic control between the sessions with exercise during the first two hours and the sessions with exercise during the last 30 min. There was no association between intra-dialytic hypotensive events at rest (five events) or exercise at any point (two vs. one event(s), respectively). Conclusion: performing exercise with virtual reality at the end of a hemodialysis session is not associated with hemodynamic instability.

Impact of the Nutrition-Inflammation Status on the Functionality of Patients with Chronic Kidney Disease

Functional capacity of chronic kidney disease (CKD) patients is compromised by their nutrition-inflammation status. We evaluated the functional capacity of advanced chronic kidney disease (ACKD) patients and the influence of the nutrition-inflammation status. In a cross-sectional study, which included ACKD patients from the nephrology department of the Hospital Universitario de la Princesa in Madrid, Spain, we assessed: functional capacity with the Short Physical Performance Battery (SPPB) test, interpreting a result <7 in the test as low functionality; body composition with monofrequency bioimpedance; muscular strength with hand grip strength; nutritional and inflammatory status using biochemical parameters and the Malnutrition Inflammation Scale (MIS). A total of 255 patients with ACKD were evaluated, 65.8% were men, their mean age was 70.65 ± 11.97 years and 70.2% of the patients had an age >65 years. The mean score of SPPB was 8.50 ± 2.81 and 76.4% of the patients presented a score ≥7, with a higher percentage in the group of men. The percentage of patients with limitations increased with age. The patients with SPPB values higher than 7 showed high values of albumin and low soluble C-reactive protein (s-CRP) and MIS. We found better functionality in well-nourished patients. A multivariate logistic regression model established an association of high albumin values with a better functional capacity (OR: 0.245 CI: 0.084−0.714 p < 0.010), while another model showed an association between CRP values and decreased functionality (OR: 1.267 CI: 1.007−1.594 p = 0.044). Conclusion: nutritional status and body composition influence on the functional capacity of patients with ACKD.

Impact of COVID-19 Pandemic on Health-Related Quality of Life and Physical Activity of Patients in Hemodialysis

Chronic dialysis patients have an increased risk of severe COVID-19 infection-related complications. The aim of this study was to quantify the impact of the COVID-19 pandemic on health-related quality of life (HRQoL) and physical activity levels of patients undertaking hemodialysis (HD). This was an observational study that compared data from two periods of time, before the COVID-19 pandemic vs pandemic. We used the Medical Outcomes Survey Short Form (SF-36) to measure the HRQoL and the Human Activity Profile (HAP) questionnaire was used to measure the physical activity. Data were analyzed with a mixed ordinal linear regression. A total of 27 eligible participants were interviewed during COVID-19 pandemic (median age 78 years). The linear regression model showed that the pandemic, after controlling for the covariates age, comorbidity, albumin, and hemoglobin, had a significant impact on the HRQoL. Physical function (-15.7) and social functioning subscales (-28.0) worsened (p = 0.001), and the physical component scale also showed a significant decrease (-3.6; p = 0.05). Time had a significant impact on the Human Activity Profile, with an average activity score diminished with the pandemic (-13.9; p = 0.003). The COVID-19 pandemic had a very negative impact on HRQoL and physical activity level of subjects undertaking hemodialysis. Interventions to improve HRQoL and activity levels of patients undertaking HD are recommended.

Impact of measurement timing on reproducibility of testing among haemodialysis patients

Accurate evaluation of physical function in patients undergoing haemodialysis is crucial in the analysis of the impact of exercise programs in this population. The aim of this study was to evaluate the reproducibility of several physical functional tests, depending on the timing of their implementation (before the HD session vs. non-HD days). This is a prospective, non-experimental, descriptive study. Thirty patients in haemodialysis were evaluated twice, 1 week apart. The test session was performed before the haemodialysis session started and a retest was performed in non-dialysis day. The testing battery included the short physical performance battery, sit-to-stand tests, 6 min walk test, one-leg stand test, timed up and go, and handgrip strength with and without forearm support. The intra-rater reproducibility was determined by the intraclass correlation coefficients and the agreement was assessed by Bland–Altman analysis. The intraclass correlation coefficients values ranged from 0.86 to 0.96, so that all tests showed good to very good relative reliability. The mean differences between trials of sit to stand 10 and 60, timed up and go and all the handgrip tests were close to zero, indicating no systematic differences between trials. Large range of values between trials was observed for the 6 min walk test, gait speed, one-leg stand test and short physical performance battery, indicating a systematic bias for these four tests. In conclusion,  the sit to stand 10 and 60, timed up and go and handgrip tests had good to excellent test–retest reliability in measuring physical function in different dialysis days of patients undertaking haemodialysis. The minimal detectable change values are provided for this population. Bias were found for the 6 min walk test, gait speed, Short physical performance battery or one-leg stand test when the testing day changed.

Fatigability and the Role of Neuromuscular Impairments in Chronic Kidney Disease

BACKGROUND

The combination of neuromuscular impairments plus psychosocial aspects of chronic kidney disease (CKD) may predispose these patients to greater risk for experiencing increased levels of fatigability. There has been extensive clinical and scientific interest in the problem of fatigue in CKD and end-stage kidney disease (ESKD) patients, whereas less attention has been directed to understanding fatigability. Accordingly, the primary purposes of this review are to (1) discuss fatigue and fatigability and their potential interactions in patients with CKD and ESKD, (2) provide evidence for increased fatigability in CKD and ESKD patients, (3) examine how commonly experienced neuromuscular impairments in CKD and ESKD patients may contribute to the severity of performance fatigability, and (4) highlight preliminary evidence on the effects of exercise as a potential clinical treatment for targeting fatigability in this population.

SUMMARY

Fatigue is broadly defined as a multidimensional construct encompassing a subjective lack of physical and/or mental energy that is perceived by the individual to interfere with usual or desired activities. In contrast, fatigability is conceptualized within the context of physical activity and is quantified as the interactions between reductions in objective measures of performance (i.e., performance fatigability) and perceptual adjustments regulating activity performance (i.e., perceived fatigability). We propose herein a conceptual model to extend current understandings of fatigability by considering the interactions among fatigue, perceived fatigability, and performance fatigability. Neuromuscular impairments reported in patients with CKD and ESKD, including reductions in force capacity, skeletal muscle atrophy, mitochondrial dysfunction, abnormal skeletal muscle excitability, and neurological complications, may each contribute to the greater performance fatigability observed in these patients.

KEY MESSAGES

Considering the interactions among fatigue, perceived fatigability, and performance fatigability provides a novel conceptual framework to advance the understanding of fatigability in CKD and ESKD patients. Measures of fatigability may provide valuable clinical insights into the overall health status of CKD and ESKD patients. Existing data suggest that CKD and ESKD patients are at greater risk of experiencing increased fatigability, partly due to neuromuscular impairments associated with reduced kidney function. Further investigations are warranted to determine the potential clinical role fatigability measures can play in monitoring the health of CKD and ESKD patients, and in identifying potential treatments targeting fatigability in this patient population.

Association of physical function and performance with peak VO2 in elderly patients with end stage kidney disease

BACKGROUND

Physical function is impaired in end stage renal disease (ESRD). Various instruments have been used to assess the functional capabilities and health status of patients with ESRD, but it is not known which has the best association with peak VO₂.

AIMS

To assess the association between functional measures in ESRD.

METHODS

Thirty nine elderly ESRD patients were evaluated with commonly used functional, health status, and quality of life measures, including maximal cardiopulmonary exercise testing (CPET), 6-min walk (6MWT), sit-to-stand test (STS), Veterans Specific Activity Questionnaire (VSAQ), upper and lower body strength, pulmonary function tests, and body composition determined by dual X-ray absorptiometry. The association between performance on these functional tools, clinical variables, and exercise test responses was assessed, and a non-exercise test multivariate model was developed to predict peak VO₂.

RESULTS

Peak VO₂ was modestly related to VSAQ score (r = 0.59, p < 0.01), indices of upper and lower body strength (r = 0.45, p < 0.01 for both), and FEV₁ (r = 0.51, p < 0.01). Functional and quality of life questionnaires were generally poorly related to one another and to peak VO₂. In a multivariate model, 6MWT performance, forced expiratory volume in 1 s (FEV₁), and VSAQ score were the best predictors of peak VO₂, yielding a multiple R = 0.82, accounting for 67% of the variance in peak VO₂.

CONCLUSION

Exercise capacity can be reasonably estimated using non-exercise test variables in patients with ESRD, including a symptom questionnaire (VSAQ), 6MWT and FEV₁.

CLINICAL TRIAL INFORMATION

ClinicalTrials.gov identifier: NCT01990495. Registered Nov 21, 2013.

Design and methodology of the chronic kidney disease as a dysmetabolic determinant of disability among older people (CKD-3D) study: a multicenter cohort observational study

Background

Chronic kidney disease (CKD) is a common condition in older people and represents a global health issue since it increases the risk of associated comorbidities and all-cause mortality. Furthermore, older people with reduced renal function might be at higher risk for developing functional limitation and disability. Moreover, the current creatinine-based measures of renal function are influenced by several factors in older population. The aims of the CKD-3D project are to perform an observational study to expand the knowledge about CKD-disability relationship and to investigate the use of novel biomarkers of kidney function.

Methods

An observational, multicenter, prospective cohort study will be conducted in 75 + old patients consecutively admitted to acute care wards of geriatric medicine at participating hospitals. The study planned to enroll 440 patients undergoing clinical and laboratory evaluations at baseline and after 12 months. Face-to-face follow-up at 6 months and telephone follow-up at 3 and 9 months will be carried out. Comprehensive Geriatric Assessment (CGA) and the measurement of Cystatin C, Beta-Trace Protein and Beta2-Microglobulin levels will be included.

Discussion

This study will provide useful information to prevent CKD-related disability by collecting real-life data over 1-year period. The combined approach of CGA and the investigation of innovative existing biomarkers will make it possible to develop new recommendations and guidelines for a patient-centered approach. It is believed that such a study may lead to an improvement of knowledge on CKD in elderly patients and may also have implications in daily clinical practice and in decision-making process.

Relationship between quadriceps thickness and 60-second sit-to-stand test in patients with chronic kidney disease

Background:

This study aimed to evaluate the relationship between quadriceps muscle thickness and functional performance on the 60s sit-to-stand test (60s-STS), the six-minute walk test (6MWT), and handgrip strength in non-dialytic stage 4 and 5 chronic kidney disease (CKD) patients.

Methods:

This was a cross-sectional study that evaluated 40 CKD patients aged between 30-70 years. Participants were submitted to an assessment that included quadriceps muscle thickness evaluated by a portable ultrasound. Functional performance tests included the 60s-STS, distance walked in the 6MWT, and handgrip strength. Also, body composition evaluated using electrical bioimpedance analysis and physical activity level through the short version of International Physical Activity were measured. Multiple linear regression was used to investigate the relationship between the quadriceps thickness and functional performance.

Results:

Quadriceps muscle thickness was correlated to 60s-STS (R2 = 43.6%; 95% CI = 0.022 - 0.665; β = 0.34; p = 0.037). Also, a moderate correlation between this muscle thickness and appendicular skeletal muscle (ALM) was found in CKD patients (r = 0.603, p <0.001). No relationship was found between quadriceps muscle thickness with the 6MWT and handgrip strength.

Conclusion:

Quadriceps muscle thickness is associated to 60s-STS, thus our results demonstrate the repercussions of the disease on the musculoskeletal system.

Pulmonary function, muscle strength, and quality of life have differed between chronic kidney disease patients and healthy individuals

Chronic kidney disease (CKD) patients have lower pulmonary function, respiratory and peripheral muscle strength values when compared to the general population, which reflects negatively in the quality of life (QoL). The aim of this study was to compare the pulmonary function, respiratory and peripheral muscle strength, and QoL between CKD patients and healthy individuals. Cross-sectional study with a consecutive sample of 39 individuals separated into three groups: nondialysis-dependent CKD in stage 5 (CKD-5), HD group (CKD-HD), and healthy individuals. The tests performed were spirometry, manovacuometry, handgrip strength (HGS), and Medical Outcomes Short-Form Health Survey (SF-36). A significant difference between groups was observed in forced expiratory volume in 1 second (FEV₁ ) and its predicted value (p = 0.004 and p < 0.001, respectively), forced vital capacity (FVC), and its predicted value (p = 0.008 and p < 0.001, respectively), peak expiratory flow (PEF) and its predicted value (p = 0.004 and p < 0.001, respectively), maximal inspiratory pressure (MIP) and its predicted value (p = 0.022), maximal expiratory pressure (MEP) and its predicted value (p = 0.030 and p = 0.009, respectively) in which CKD-5 presented the worst values, followed by CKD-HD and healthy group. The CKD-5 had worse pulmonary function, respiratory muscle strength, and QoL. Moreover, CKD-HD also showed some impairment in pulmonary function and QoL when compared with healthy individuals. Even with the peripheral muscle strength preserved, its decrease is proportional to the pulmonary impairment in the evaluated CKD patients.

Prevalence and correlates of physical activity across kidney disease stages: an observational multicentre study

BACKGROUND

People with chronic kidney disease (CKD) report high levels of physical inactivity, a major modifiable risk factor for morbidity and mortality. Understanding the biological, psychosocial and demographic causes of physical activity behaviour is essential for the development and improvement of potential health interventions and promotional initiatives. This study investigated the prevalence of physical inactivity and determined individual correlates of this behaviour in a large sample of patients across the spectrum of kidney disease.

METHODS

A total of 5656 people across all stages of CKD (1-2, 3, 4-5, haemodialysis, peritoneal dialysis and renal transplant recipients) were recruited from 17 sites in England from July 2012 to October 2018. Physical activity was evaluated using the General Practice Physical Activity Questionnaire. Self-reported cardiorespiratory fitness, self-efficacy and stage of change were also assessed. Binominal generalized linear mutually adjusted models were conducted to explore the associations between physical activity and correlate variables. This cross-sectional observational multi-centre study was registered retrospectively as ISRCTN87066351 (October 2015).

RESULTS

The prevalence of physical activity (6-34%) was low and worsened with disease progression. Being older, female and having a greater number of comorbidities were associated with greater odds of being physically inactive. Higher haemoglobin, cardiorespiratory fitness and self-efficacy levels were associated with increased odds of being active. Neither ethnicity nor smoking history had any effect on physical activity.

CONCLUSIONS

Levels of physical inactivity are high across all stages of CKD. The identification of stage-specific correlates of physical activity may help to prioritize factors in target groups of kidney patients and improve the development and improvement of public health interventions.

Exercise training during hemodialysis in Brazil: A national survey

To evaluate the availability and characteristics of exercise training during hemodialysis in Brazil and to identify the reported barriers to exercise program implementation and maintenance. All dialysis units were assessed for eligibility using the database of the Brazilian Society of Nephrology. Each dialysis unit was contacted by telephone and the questions were administered. In dialysis units with exercise training, questions related to personnel involved, exercise components, and program delivery were included. Additionally, the barriers to exercise program implementation and maintenance were evaluated. This study included 261 dialysis units that responded to the survey. Forty-one dialysis units reported exercise training during hemodialysis in Brazil (prevalence of 15.7%). We identified 66 physiotherapists and 10 exercise physiologists in dialysis units with exercise training. Resistance training was the most common program component (92.7%). Hypotension (90.5%) and muscle cramps (85.7%) were the most common adverse events reported. In dialysis units with exercise training, poor patients' adherence to exercise was the most commonly reported barrier. The most prevalent barrier in dialysis units that tried or never tried to implement the exercise programs was a lack of resources. The number of dialysis units that have exercise training during hemodialysis in Brazil is low, and the most common program component is resistance training. A lack of resources was the most prevalent barrier in dialysis units that tried or never tried to implement the exercise programs.

Post-COVID-19 rehabilitation: a special look at chronic kidney disease patients

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect the kidney and the presence of chronic kidney disease (CKD) constitutes a higher risk of negative prognosis. SARS-CoV-2 main sequelae in CKD patients are an incomplete recovery of kidney function, muscle weakness and atrophy, breathiness, tiredness, pulmonary fibrosis, and initiation of kidney replacement therapy. The overall aim of this review is to provide a theoretical basis for early improvements of physical function health to all CKD stages by rehabilitation therapies.

CONCLUSION

Chronic kidney disease patients infected with SARS-CoV-2 should be monitored by rehabilitation professionals as the cardiopulmonary, musculoskeletal, and cognitive systems might be deteriorated. Long-term consequences of SARS-CoV-2 are unknown and preventive rehabilitation may attenuate them.

Association between vitamin D deficiency and exercise capacity in patients with CKD, a cross-sectional analysis

BACKGROUND

Evidence is growing for a role of vitamin D in regulating skeletal muscle mass, strength and functional capacity. Given the role the kidneys play in activating total vitamin D, and the high prevalence of vitamin D deficiency in Chronic Kidney Disease (CKD), it is possible that deficiency contributes to the low levels of physical function and muscle mass in these patients.

METHODS

This is a secondary cross-sectional analysis of previously published interventional study, with in vitro follow up work. 34 CKD patients at stages G3b-5 (eGFR 25.5 ± 8.3 mL/min/1.73m2; age 61 ± 12 years) were recruited, with a sub-group (n = 20) also donating a muscle biopsy. Vitamin D and associated metabolites were analysed in plasma by liquid chromatography tandem-mass spectroscopy and correlated to a range of physiological tests of muscle size, function, exercise capacity and body composition. The effects of 1α,25(OH)2D3 supplementation on myogenesis and myotube size was investigated in primary skeletal muscle cells from vitamin D deficient donors.

RESULTS

In vivo, there was no association between total or active vitamin D and muscle size or strength, but a significant correlation with V̇O_2Peak was seen with total vitamin D (25OHD). in vitro, 1α,25(OH)₂D3 supplementation reduced IL-6 mRNA expression, but had no effect upon proliferation, differentiation or myotube diameter.

CONCLUSIONS

Vitamin D deficiency is not a prominent factor driving the loss of muscle mass in CKD, but may play a role in reduced exercise capacity.

Factors associated with fear of falling in hemodialysis patients

PURPOSE

Fear of falling (FOF) has important clinical and psychological consequences. This study evaluated the factors associated with FOF in hemodialysis patients and compared with the FOF reported by age-gender matched individuals without chronic kidney disease.

METHODS

This cross sectional study included hemodialysis group (n = 60, 55.4 ± 7.6 years, 55.0% male) and control group (n = 40, 55.1 ± 7.5 years, 52.5% male). FOF was assessed by the Falls Efficacy Scale International (FES-I). Physical function was evaluated using the Mini-Balance Evaluation Systems Test (Mini-BESTest), Timed Up and Go test, 4-m gait speed, isometric handgrip force and 10-repetition sit-to-stand test. The physical and mental components of quality of life was evaluated by 36-Item Short Form Health Survey.

RESULTS

The FES-I score was higher in the hemodialysis group compared to the control group (28.2 ± 9.7 vs. 23.3 ± 5.1, p = 0.020). In addition, the prevalence of individuals with a higher concern about falling was greater in the hemodialysis group (41.7 vs. 17.5%, p = 0.033). Multiple linear regression showed that the FES-I score was associated with the Mini-BESTest score and the physical component summary of quality of life (coefficient of determination of 0.51 and an adjusted coefficient of determination of 0.46).

CONCLUSION

FOF was associated with poor postural balance and reduced physical component of quality of life in patients on hemodialysis and these patients showed higher FOF compared to individuals without chronic kidney disease.

Bridging the gap from research to practice for enhanced health-related quality of life in people with chronic kidney disease

Improving the health status of people with chronic kidney disease (CKD) through physical activity (PA) or exercise interventions is challenging. One of the gaps in the process of translating the general public PA activity guidelines as well as the CKD-specific guidelines into routine clinical practice is the lack of systematic recording and monitoring of PA and physical function attributes, which can also be used to develop individualized and measurable plans of action to promote PA for health. We aim to present an overview of key considerations for PA, physical function and health-related quality of life (HRQoL) evaluation in people with CKD, with the aim of encouraging health professionals to integrate assessment of these outcomes in routine practices. Physical inactivity and impaired physical function, sometimes to the extent of physical and social disability levels, and subsequently lower perceived HRQoL, are highly prevalent in this population. Enhanced PA is associated with better physical function that also translates into multiple health benefits. Breaking the vicious circle of inactivity and physical dysfunction as early as possible in the disease trajectory may confer huge benefits and enhanced life satisfaction in the longer term. With this in mind, the importance of PA/exercise interventions in CKD to improve HRQoL is also summarized.

Muscle-Bone Crosstalk in Chronic Kidney Disease: The Potential Modulatory Effects of Exercise

Chronic kidney disease (CKD) is a prevalent worldwide public burden that increasingly compromises overall health as the disease progresses. Two of the most negatively affected tissues are bone and skeletal muscle, with CKD negatively impacting their structure, function and activity, impairing the quality of life of these patients and contributing to morbidity and mortality. Whereas skeletal health in this population has conventionally been associated with bone and mineral disorders, sarcopenia has been observed to impact skeletal muscle health in CKD. Indeed, bone and muscle tissues are linked anatomically and physiologically, and together regulate functional and metabolic mechanisms. With the initial crosstalk between the skeleton and muscle proposed to explain bone formation through muscle contraction, it is now understood that this communication occurs through the interaction of myokines and osteokines, with the skeletal muscle secretome playing a pivotal role in the regulation of bone activity. Regular exercise has been reported to be beneficial to overall health. Also, the positive regulatory effect that exercise has been proposed to have on bone and muscle anatomical, functional, and metabolic activity has led to the proposal of regular physical exercise as a therapeutic strategy for muscle and bone-related disorders. The detection of bone- and muscle-derived cytokine secretion following physical exercise has strengthened the idea of a cross communication between these organs. Hence, this review presents an overview of the impact of CKD in bone and skeletal muscle, and narrates how these tissues intrinsically communicate with each other, with focus on the potential effect of exercise in the modulation of this intercommunication.

Hemodialysis patients perceived exercise benefits and barriers: the association with health-related quality of life

BACKGROUND

Patients on hemodialysis have less exercise capacity and lower health-related quality of life than healthy individuals without chronic kidney disease (CKD). One of the factors that may influence exercise behavior among these patients is their perception of exercise benefits and barriers. The present study aimed to assess the perception of hemodialysis patients about exercise benefits and barriers and its association with patients' health-related quality of life.

METHODS

In this cross-sectional study, 227 patients undergoing hemodialysis were randomly selected from two dialysis centers. Data collection was carried out using dialysis patient-perceived exercise benefits and barriers scale (DPEBBS) and kidney disease quality of life short form (KDQOL-SF). Data were analyzed using SPSS software ver. 21.

RESULTS

The mean score of DPEBBS was 68.2 ± 7.4 (range: 24 to 96) and the mean KDQOL score was 48.9 ± 23.3 (range: 0 to 100). Data analysis by Pearson correlation coefficient showed a positive and significant relationship between the mean scores of DPEBBS and the total score of KDQOL (r = 0.55, p < 0.001). Moreover, there was a positive relationship between the mean scores of DPEBBS and the mean score of all domains of KDQOL.

CONCLUSION

Although most of the patients undergoing hemodialysis had a positive perception of the exercise, the majority of them do not engage in exercise; it could be contributed to the barriers of exercise such as tiredness, muscle fatigue, and fear of arteriovenous fistula injury. Providing exercise facilities, encouraging the patients by the health care provider to engage in exercise programs, and incorporation of exercise professionals into hemodialysis centers could help the patients to engage in regular exercise.

Impact of virtual reality interventions on haemodialysis patients: A scoping review

BACKGROUND

An understanding of the potential of virtual reality to affect the level of engagement in self-care and health-related quality of life is required for patients receiving haemodialysis.

OBJECTIVE

This scoping review aimed to collate, summarise, and report on related study findings to identify evidence gaps and draw conclusions from the existing literature.

METHODS

The methodological steps outlined in the Arksey and O'Malley framework combined with modifications of Levac and colleagues guided this systematic scoping review. MEDLINEComplete, Embase, CINAHLComplete and PsychINFO databases were searched. Additionally, hand searches of key articles and journals were performed.

RESULTS

From the database searches, 610 studies were identified with 11 meeting the inclusion criteria; another study was added after searching reference lists of included articles, resulting in 12 included articles. The quality, study design and type of virtual reality intervention varied. Only three studies used immersive virtual reality. Several studies demonstrated significant improvement in the physical activity level and a reduction in fatigue in patients during haemodialysis, with no adverse events. Despite the demands of haemodialysis sessions, this study showed that virtual reality interventions may improve the level of haemodialysis patients' adherence and engagement with treatment.

CONCLUSIONS

Findings favour the use of virtual reality to improve physical health and engagement with treatment. However, there is a need for more rigorous study designs within different clinical settings to provide high-quality evidence regarding other ways that virtual reality interventions could improve the quality of life of haemodialysis patients.

The "Minimum Clinically Important Difference" in Frequently Reported Objective Physical Function Tests After a 12-Week Renal Rehabilitation Exercise Intervention in Nondialysis Chronic Kidney Disease

OBJECTIVE

Chronic kidney disease patients are characterized by impaired physical function. The goal of exercise-based interventions is an improvement in functional performance. However, improvements are often determined by "statistically significant" changes. We investigated the "minimum clinically important difference," "the smallest change that is important to the patient," for commonly reported physical function tests.

DESIGN

Nondialysis chronic kidney disease patients completed 12-wks of a combined aerobic (plus resistance training). The incremental shuttle walking test, sit-to-stand 5 and 60, estimated 1-repetition maximum for the knee extensors, and VO2peak were assessed. After the intervention, patients rated their perceived change in health. Both anchor- and distribution-based minimum clinically important difference approaches were calculated.

RESULTS

The minimum clinically important difference was calculated as follows: incremental shuttle walking test, +45 m; sit-to-stand 5, -4.2 secs; VO2peak, +1.5 ml/kg per min. Because of comparable increases in "anchor" groups, no minimum clinically important difference was estimated for the sit-to-stand 60 or estimated 1-repetition maximum.

CONCLUSIONS

We have established the minimum clinically important difference in chronic kidney disease for common tests of physical function. These values represent the minimum change required for patients to perceive noticeable and beneficial change to their health. These scores will help interpret changes after exercise interventions where these tests are used. These minimum clinically important differences can be used to power future studies to detect clinically important changes.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Define the "minimum clinically important difference"; (2) Distinguish between concepts of minimum clinically important difference, "minimal detectable change,", and "statistically significant change"; and (3) Interpret other study findings and their own results in the context of the minimum clinically important difference rather than statistically significant changes.

LEVEL

Advanced ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Ultrasound assessment of muscle mass in response to exercise training in chronic kidney disease: a comparison with MRI

BACKGROUND

Chronic kidney disease (CKD) is a catabolic condition associated with muscle wasting and dysfunction, which associates with morbidity and mortality. There is a need for simple techniques capable of monitoring changes in muscle size with disease progression and in response to interventions aiming to increase muscle mass and function. Ultrasound is one such technique; however, it is unknown how well changes in muscle cross-sectional area (CSA) measured using ultrasound relate to changes in whole muscle volume measured using magnetic resonance imaging. We tested whether rectus femoris CSA (RF-CSA) could be used as a valid indication of changes in quadriceps muscle volume as a single measure of muscle size and following a 12 week exercise intervention that resulted in muscle hypertrophy.

METHODS

Secondary analysis of data was collected from the ExTra CKD study (ISRCTN 36489137). Quadriceps muscle size was assessed from 36 patients with non-dialysis CKD before and after 12 weeks of supervised exercise that resulted in muscle hypertrophy.

RESULTS

Strong positive correlations were observed between RF-CSA and quadriceps volume at baseline (r² = 0.815, CI 0.661 to 0.903; P < 0.001) and following 12 week exercise (r² = 0.845, CI 0.700 to 0.923; P < 0.001). A moderate positive association was also observed between changes in RF-CSA and quadriceps following exercise training (rho = 0.441, CI 0.085 to 0.697; P = 0.015). Bland-Altman analysis revealed a small bias (bias 0.6% ± 12.5) between the mean percentage changes in RF-CSA and quadriceps volume but wide limits of agreement from -24 to 25.

CONCLUSIONS

Rectus femoris CSA appears to be a reliable index of total quadriceps volume as a simple measure of muscle size, both as a single observation and in response to exercise training in non-dialysis CKD patients.

Postural stability during standing and its association with physical and cognitive functions in non-dialysis chronic kidney disease patients

PURPOSE

Chronic kidney disease (CKD) is characterised by poor physical function. A possible factor may be aberrant changes to balance and postural stability (i.e. ability to maintain centre of pressure (COP)). Previous research has exclusively focused on patients undergoing renal replacement therapy (RRT). The current study investigated postural stability in a group of CKD patients not requiring RRT.

METHODS

30 CKD patients (aged 57.0 ± 17.8 years, 47% female, mean eGFR 42.9 ± 27.2 ml/kg/1.73 m²) underwent a series of physical function assessments including the sit-to-stand-5 and -60, incremental shuttle walk test, gait speed, and short physical performance battery. Postural stability (defined as total COP ellipse (mm²) displacement) was measured using the Fysiometer board. Control reference data were provided by the manufacture. Cognitive function was assessed using the 'Montreal Cognitive Assessment-Basic' (MOCA-B)'.

RESULTS

CKD patients had poorer postural stability during quiet standing than reference values across all age categories (≤ 39 years, 24.9 ± 11.3 vs. 10.4 ± 1.8 mm²; 40-59 years, 34.3 ± 19.0 vs. 17.7 ± 6.2 mm²; ≥ 60 years, 39.7 ± 21.2 vs. 16.8 ± 2.9 mm², all comparisons P < 0.001). Reductions in postural stability were associated with both physical and cognitive functioning. In females only, postural stability worsened with declining renal function (r = - 0.790, P < 0.01).

CONCLUSIONS

To our knowledge, this is the first and largest experimental report concerning measurement of postural stability of CKD patients not requiring RRT. Our findings suggest that postural stability is associated with worse physical and cognitive functioning in this patient group.

Implications of low muscle mass across the continuum of care: a narrative review

Abnormalities in body composition can occur at any body weight. Low muscle mass is a predictor of poor morbidity and mortality and occurs in several populations. This narrative review provides an overview of the importance of low muscle mass on health outcomes for patients in inpatient, outpatient and long-term care clinical settings. A one-year glimpse at publications that showcases the rapidly growing research of body composition in clinical settings is included. Low muscle mass is associated with outcomes such as higher surgical and post-operative complications, longer length of hospital stay, lower physical function, poorer quality of life and shorter survival. As such, the potential clinical benefits of preventing and reversing this condition are likely to impact patient outcomes and resource utilization/health care costs. Clinically viable tools to measure body composition are needed for routine screening and intervention. Future research studies should elucidate the effectiveness of multimodal interventions to counteract low muscle mass for optimal patient outcomes across the healthcare continuum. Key messages Low muscle mass is associated with several negative outcomes across the healthcare continuum. Techniques to identify and counteract low muscle mass in clinical settings are needed.

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

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

Association of self-reported physical function with survival in patients with chronic kidney disease

Background

Reduced physical function is associated with an increased risk of mortality among patients with chronic kidney disease (CKD) not requiring renal replacement therapy (RRT). Assessments of physical performance can help to identify those at risk for adverse events. However, objective measures are not always feasible and self-reported measures may provide a suitable surrogate.

Methods

We performed a cohort study examining associations between self-reported physical function and walking behaviour with survival in patients with CKD not requiring RRT. Data were analysed from the QCKD study (Physical activity opinions in kidney disease) (ISRCTN 87066351), a prospective observational mixed methods study of physical activity in patients with CKD. A total of 450 patients with CKD not requiring RRT, ages 17–93 years, were followed up for a median of 43 months. Upon enrolment, participants completed two questionnaires: Duke Activity Status Index (DASI) (physical function) and General Practice Physical Activity Questionnaire (GPPAQ) (habitual activity). Mortality data were collected from electronic records in September 2016; RRT was considered a competing event.

Results

A total of 74 deaths occurred during follow-up and 101 participants were started on RRT. The adjusted subdistribution hazard ratio (SHR) of mortality in participants scoring >19.2 on the DASI was 0.51 [95% confidence interval (CI) 0.30–0.88] while a one-unit increase in the DASI was associated with an SHR of 0.97 (95% CI 0.95–0.99). The adjusted SHRs of mortality were 0.48 (95% CI 0.26–0.90), 0.25 (0.11–0.57) and 0.48 (0.23–0.80) for participants walking <1, 1–3 and ≥3 h/week, respectively, compared with no walking. A walking pace >3 mph was associated with a reduced risk of mortality [SHR 0.37 (95% CI 0.20–0.71)] compared with a walking pace <3 mph.

Conclusions

Physical function and walking behaviours were independently associated with survival in CKD and may help to identify patients at risk for adverse events.

Chronic kidney disease: considerations for monitoring skeletal muscle health and prescribing resistance exercise

Skeletal muscle wasting has gained interest as a primary consequence of chronic kidney disease (CKD) due to the relationship between skeletal muscle mass, mortality and major adverse cardiovascular events in this population. The combination of reductions in physical function, skeletal muscle performance and skeletal muscle mass places individuals with CKD at greater risk of sarcopenia. Therefore the monitoring of skeletal muscle composition and function may provide clinical insight into disease progression. Dual-energy X-ray absorptiometry and bioelectrical impedance analysis are frequently used to estimate body composition in people with CKD within clinical research environments, however, their translation into clinical practice has been limited. Proxy measures of skeletal muscle quality can be obtained using diagnostic ultrasound, providing a cost-effective and accessible imaging modality to aid further clinical research regarding changes in muscle composition. Clinicians and practitioners should evaluate the strengths and limitations of the available technology to determine which devices are most appropriate given their respective circumstances. Progressive resistance exercise has been shown to improve skeletal muscle hypertrophy of the lower extremities, muscular strength and health-related quality of life in end-stage renal disease, with limited evidence available in CKD predialysis. Fundamental principles (i.e. specificity, overload, variation, reversibility, individuality) can be used in the development of more advanced programs focused on improving specific neuromuscular and functional outcomes. Future research is needed to determine the applicability of skeletal muscle monitoring in clinical settings and the feasibility and efficacy of more advanced resistance exercise approaches in those with CKD predialysis.

Quality over quantity? Association of skeletal muscle myosteatosis and myofibrosis on physical function in chronic kidney disease

Background

Chronic kidney disease (CKD) is characterized by adverse changes in body composition, which are associated with poor clinical outcome and physical functioning. Whilst size is the key for muscle functioning, changes in muscle quality specifically increase in intramuscular fat infiltration (myosteatosis) and fibrosis (myofibrosis) may be important. We investigated the role of muscle quality and size on physical performance in non-dialysis CKD patients.

Methods

Ultrasound (US) images of the rectus femoris (RF) were obtained. Muscle quality was assessed using echo intensity (EI), and qualitatively using Heckmatt’s visual rating scale. Muscle size was obtained from RF cross-sectional area (RF-CSA). Physical function was measured by the sit-to-stand-60s (STS-60) test, incremental (ISWT) and endurance shuttle walk tests, lower limb and handgrip strength, exercise capacity (VO2peak) and gait speed.

Results

A total of 61 patients (58.5 ± 14.9 years, 46% female, estimated glomerular filtration rate 31.1 ± 20.2 mL/min/1.73 m2) were recruited. Lower EI (i.e. higher muscle quality) was significantly associated with better physical performance [STS-60 (r = 0.363) and ISWT (r = 0.320)], and greater VO2peak (r = 0.439). The qualitative rating was closely associated with EI values, and significant differences in function were seen between the ratings. RF-CSA was a better predictor of performance than muscle quality.

Conclusions

In CKD, increased US-derived EI was negatively correlated with physical performance; however, muscle size remains the largest predictor of physical function. Therefore, in addition to the loss of muscle size, muscle quality should be considered an important factor that may contribute to deficits in mobility and function in CKD. Interventions such as exercise could improve both of these factors.