The relationship between extracellular water-to-body water ratio and sarcopenia according to the newly revised Asian Working Group for Sarcopenia: 2019 Consensus Update

The SARC-F score may indirectly reflect the extracellular water-to-total body water ratio

BACKGROUND & AIMS

In the Asian Working Group for Sarcopenia 2019 guidelines, SARC-F is used to screen for sarcopenia. SARC-F is measured based on five components: strength, assistance with walking, rising from a chair, climbing stairs, and falling. However, it has been reported that SARC-F has high specificity but low sensitivity for sarcopenia screening. Considering that SARC-F is currently recommended for sarcopenia screening, indicating the utility of SARC-F not only in sarcopenia screening but also in other aspects is pivotal. This cross-sectional study aimed to clarify the relationship between the SARC-F score and the extracellular water-to-total body water ratio (ECW/TBW) in community-dwelling older people.

METHODS

This study included 167 community-dwelling older people (aged ≥65) who were able to walk independently and used the SARC-F as a screening test for sarcopenia diagnosis. ECW/TBW and the skeletal muscle mass index (SMI) were measured using bioelectrical impedance analysis. The associations among the SARC-F score, ECW/TBW, and SMI were assessed using Spearman's correlation coefficient. Multiple linear regression analyses of the SARC-F score were conducted. Age, sex, number of medications, pain, medical history, ECW/TBW, and SMI were considered independent variables in multiple linear regression analysis.

RESULTS

The analyses revealed a significant positive correlation between the SARC-F score and ECW/TBW (ρ = 0.473, p < 0.001). SMI was significantly and negatively correlated with the SARC-F score (ρ = -0.233, p = 0.002). In the multiple linear regression analysis, ECW/TBW (β = 0.311, p < 0.001) and prevalence of pain (β = 0.169, p = 0.023) were significantly and independently associated with the SARC-F score (R2 = 0.260). SMI was not significantly associated with the SARC-F score (β = 0.002, p = 0.986).

CONCLUSION

This study revealed a positive correlation between SARC-F score and ECW/TBW in community-dwelling older people, and this relationship persisted even after adjusting for confounding factors. However, there was no correlation between the SARC-F score and SMI. Our study indicated that the SARC-F score may be considered an indirect indicator of ECW/TBW. The score might also be useful for discriminating high and low ECW/TBW. These findings highlight a new use for SARC-F.

Exploring Biomarkers for Excess Extracellular Fluid in the Context of Physical Function in Chronic Kidney Disease Patients

Background/Objectives: Fluid overload is an important risk factor for protein-energy wasting, which could lead to poor outcomes, such as higher morbidity and mortality, in patients with chronic kidney disease (CKD). This study aimed to validate the possible myokine as a biomarker of volume status in patients with non-dialysis CKD. Methods: In total, 151 patients with CKD were enrolled from a single medical center. Demographic data were collected via medical record review. Bioimpedance analysis was performed to measure body composition, and physical performance was assessed by measuring hand grip strength. Results: The physical performance of hand grip strength (21.9 ± 8.7 vs. 19.0 ± 10.1 kg, p = 0.233) and walking speed (1.05 ± 0.29 vs. 0.86 ± 0.52 m/s, p = 0.192) was higher in the low extracellular water/total body water (ECW/TBW) ratio group. Although higher, the median value of the brain-derived neurotrophic factor (BDNF) was not significant in the low ECW/TBW ratio group. Despite that, it had significant negative correlations with the ECW/TBW ratio in Pearson's correlation analyses (r = -0.329, p < 0.001; r = -0.287, p < 0.001; and r = -0.238, p = 0.003). Linear regression analysis showed that the BDNF level had a significant negative relationship with the ECW/TBW ratio and significant associations even after multivariate analysis. Conclusions: Among myokines, BDNF had a significant negative relationship with the ECW/TBW ratio, suggesting that BDNF could be a possible biomarker for volume status in patients with non-dialysis CKD.

Factors associated with an improvement in extracellular water-to-total body water ratio in older adults with hip fractures: A decision tree analysis

BACKGROUND & AIMS

The extracellular water-to-total body water ratio (ECW/TBW) increases with age and after fractures. A high ECW/TBW may hinder improvements in physical function and skeletal muscle mass. However, the effects of ECW/TBW improvement have not been properly investigated. The aim of this study was to investigate the factors associated with ECW/TBW improvement in older adults with hip fractures.

METHODS

This retrospective cohort study included 203 patients with hip fractures who were admitted to a convalescent rehabilitation ward. ECW/TBW and skeletal muscle mass index (SMI) were measured using bioelectrical impedance analysis. The patients were classified into two groups: those with an improvement in ECW/TBW (n = 123) and those without an improvement (n = 80). Decision tree analysis was performed to examine the factors associated with ECW/TBW improvement. As a secondary objective, a multiple regression analysis was performed to identify the factors associated with SMI gain.

RESULTS

Decision tree analysis identified rehabilitation volume and protein intake as the first and second factors most significantly associated with an improvement in ECW/TBW, respectively. Multiple regression analysis showed that improved ECW/TBW (β: 0.400, p < 0.001) was significantly associated with SMI gain.

CONCLUSIONS

Rehabilitation volume and protein intake are clinically important for improving ECW/TBW in older adults with hip fractures.

Proposal and validation of an equation to identify sarcopenia using bioelectrical impedance analysis-derived parameters

OBJECTIVE

This study aimed to develop a simpler approach for diagnosing sarcopenia by using only bioelectrical impedance vector analysis parameters.

METHODS

The study design was a cross-sectional study. The research was conducted based on the Itabashi Longitudinal Study on Aging, a community-based cohort study, with data collected from the 2022 and 2023 surveys in Itabashi Ward, Tokyo, Japan. The development cohort consisted of 1146 participants from the 2022 survey, and the validation cohort included 656 participants from the 2023 survey. Both cohorts were comprised of community-dwelling older adults with similar inclusion criteria. Sarcopenia was defined according to the Asian Working Group for Sarcopenia 2019 criteria. The logistic model utilized height divided by impedance at 50 kHz and phase angle to establish a new regression equation to identify sarcopenia. Regression equations were generated for the development cohort and validated for the validation cohort. Discriminatory ability was assessed using the area under the receiver operating characteristic curve (AUC) for men and women.

RESULTS

The prevalence of sarcopenia was 20.7% and 14.8% in the development and validation cohort, respectively. The AUC (95% confidence interval) of the logistic model in discriminating sarcopenia was 0.92 (0.88, 0.95) for men and 0.82 (0.78, 0.86) for women in the development cohort and 0.85 (0.78, 0.91) for men and 0.90 (0.86, 0.95) for women in the validation cohort.

CONCLUSION

The study demonstrated that a simple formula using bioelectrical parameters at 50 kHz proved useful in identifying sarcopenia in the older adult population.

Body composition characteristics and influencing factors of different parts of sarcopenia in elderly people: A community-based cross-sectional survey

Objectives

This study aims to describe the differences in body composition among different body parts of the elderly in the community and its relationship with sarcopenia.

Methods

Elderly people aged ≥65 underwent bioelectric impedance analysis testing and were categorized into a sarcopenia group, possible sarcopenia group, and control group. The characteristics of body composition indicators in different parts and their relationship with different stages of sarcopenia were analyzed.

Results

The sarcopenia group illustrated the lowest values of FFM, FFM%, BFM, BFM%, ICW, and limb PhA, along with higher ECW/TBW in the trunk and left leg compared to the control group. The possible sarcopenia group showed lower FFM% in limbs and trunk, and higher BFM% compared to the control group. Gender differences in elderly body composition were observed, with an increase in BFM% in various body parts posing a risk factor for possible sarcopenia in elderly males, whereas an increase in BFM% except in the left arm was a protective factor for sarcopenia in elderly females.

Conclusion

The body composition of the elderly in the community varied significantly in different stages of sarcopenia and genders, which correlated with sarcopenia.

Influence of aging on extracellular water-to-total body water ratio in community-dwelling females

BACKGROUND & AIMS

The European Working Group of Sarcopenia in Older People 2 has emphasized the significance of evaluating not only muscle mass but also muscle quality as a diagnostic criterion for sarcopenia. The extracellular water-to-total body water ratio (ECW/TBW), measured using bioelectrical impedance analysis (BIA), has recently received attention as an indicator of muscle quality. However, the influence of aging on the ECW/TBW remains unclear. If ECW/TBW increases with age, it is important to know whether the timing of the decrease in SMI and the increase in ECW/TBW are the same or different. This study aimed to investigate the influence of aging on ECW/TBW in community-dwelling females.

METHODS

This cross-sectional study included 237 community-dwelling females aged 20-89 years who could perform activities of daily living independently. ECW/TBW and SMI were measured using BIA. Multiple linear regression analyses of ECW/TBW and SMI were conducted. Age, body mass index (BMI), number of medications, pain, and medical history were considered independent variables in the multiple linear regression. The participants were divided into three (20-39, 40-64, and 65-89 years) or four (20-39, 40-64, 65-74, and 75-89 years) groups based on age. Analysis of covariance adjusted for the BMI, number of medications, pain, and medical history was conducted to determine the differences in ECW/TBW and SMI among the three or four groups.

RESULTS

In the multiple linear regression analysis, age was significantly and independently associated with ECW/TBW and SMI. When the participants were divided into three groups based on age, an increase in ECW/TBW and a decrease in SMI in the 65-89-year group were confirmed compared with the 20-39 and 40-64-year groups. When the participants were divided into four groups based on age, an increase in ECW/TBW in the 75-89-year group was confirmed compared with the 65-74-year group. However, there were no significant differences in SMI among the four groups.

CONCLUSIONS

This study revealed that ECW/TBW increases with aging in community-dwelling females. Moreover, the negative influences of aging were confirmed earlier in ECW/TBW than in SMI. Assessing muscle mass alone may not be adequate to capture the influences of aging on muscle composition, and evaluating ECW/TBW may be crucial for diagnosing sarcopenia.

The impact of income level on skeletal muscle health in rural Chinese older residents: a study of mediating effects based on dietary knowledge

China's rural residents have basically solved the problem of subsistence, but due to aging, the prevalence of sarcopenia (abbreviated as sarcopenia) has been increasing year by year, especially the skeletal muscle health of the rural older residents has not been sufficiently paid attention to, so analyses of the impact of income level on the skeletal muscle health of the older people in rural areas of China are of great practical significance. Based on the annual data of the China Health and Nutrition Survey (CHNS) in 2006, 2009, and 2011, we introduced the mediator variable of dietary knowledge and used the Probit model regression, mediation effect model, and instrumental variable regression to assess the skeletal muscle health status of the rural older people in China and explore the mechanism of the influence of the income level on the skeletal muscle health of the rural older residents in China. The primary objectives of this study were to evaluate the impact of income level on the skeletal muscle health status of older adults living in rural areas of China and to investigate the underlying mechanisms. By analyzing the findings of this study, our aim is to establish a correlation between the economic status and skeletal muscle health of older adults in rural communities, as well as elucidate the influence of income level and dietary knowledge on their skeletal muscle health. Through the attainment of these objectives, we hope to provide valuable insights and recommendations for enhancing skeletal muscle health among the rural older population in China. Based on our research findings, it can be inferred that there was a significant association between the financial status of rural older adults and their skeletal muscle health. Additionally, the prevalence of sarcopenia was lower among individuals with higher income levels, and there was a negative correlation between the prevalence of sarcopenia and the level of dietary knowledge among rural older individuals. The knowledge of dietary knowledge level of rural older people plays a mediating role in the income level and the prevalence of sarcopenia. Moreover, with the change in income level and the increase in age, the change in skeletal muscle health status showed obvious heterogeneity, in which the effect on the relatively younger (65-70 years old) samples was greater. Therefore, sustained income growth remains an effective way to improve the skeletal muscle health of older rural residents. At the same time, improving dietary knowledge and dietary quality among the older people is important in preventing a decline in muscle strength and physical function and in preventing the onset of sarcopenia.

Association between ICW/TBW ratio and cancer prognosis: Subanalysis of a population-based retrospective multicenter study

BACKGROUND & AIMS

Disease burden is known to alter cellular integrity and water balance. Therefore, the intracellular water/total body water (ICW/TBW) ratio is used as an adjunctive indicator to predict disease severity and prognosis. The ICW/TBW ratio of patients with cancer, who typically present with low muscle mass, poor nutritional status, and high inflammatory response, reportedly differs from that of the healthy population. Herein, we aimed to evaluate the effect of the ICW/TBW ratio on the prognosis of different subgroups of patients with cancer.

METHODS

This multicenter cohort study included 2787 patients with malignancies between June 2014 and December 2018. The association between covariates and overall survival (OS) was assessed using restricted cubic spline models. The multivariate Cox regression model included variables demonstrating a statistical significance in the univariate Cox regression analysis (P < 0.05) without multicollinearity. The generated nomogram used the C-index and calibration curves to validate the predictive accuracy of the scoring system.

RESULTS

The optimal cut-off value for the ICW/TBW ratio was 0.61. The ICW/TBW ratio was an independent prognostic factor (hazard ratio [HR]: 0.621; 95 % confidence interval [CI]: 0.537-0.719, P < 0.001). Moreover, the ICW/TBW ratio had a greater impact on the prognosis of patients receiving chemoradiotherapy than on those receiving chemotherapy alone (chemoradiotherapy: HR = 0.495, P = 0.005 vs. chemotherapy: HR = 0.646, P < 0.001). Multivariate Cox regression analysis showed that sex, age, tumor stage, body mass index, neutrophil-to-lymphocyte ratio (NLR), and ICW/TBW ratio were associated with OS. Subsequently, a nomogram was developed incorporating these variables and yielded a C-index of 0.743.

CONCLUSIONS

The ICW/TBW ratio was associated with muscle mass, nutritional status, and inflammation. A low ICW/TBW ratio is an independent risk factor for poor prognosis in patients with cancer, especially when they are female, have advanced cancer stage, have sarcopenia, and are receiving radiotherapy.

Use of bioimpedance in prevention of sarcopenia in the elderly

OBJECTIVES

Physiological ageing is associated with major and progressive changes in body composition, particularly in the decline of fat-free mass, which puts older individuals at risk of geriatric syndromes such as sarcopenia and sarcopenic obesity. Bioimpedance analysis noninvasively allows the determination of body composition, thus being able to rapidly assess primary risk factors leading to sarcopenia prediction.

METHODS

We conducted a study of 180 probands, 120 females (66.7%) with a mean age of 76.23 (SD = 9.29) years and 60 males (33.3%) with a mean age of 74.01 (SD = 8.99) years in cooperation with facilities for the elderly and with the inpatient department of the clinics of J.A. Reimann Hospital in Prešov. Body height, body weight, hip circumference, and waist circumference were determined by the anthropometric method, from which the values of the body mass index and waist-to-hip ratio were calculated. Active body mass, total body water, extracellular body water, intracellular body water, cell mass, body mass fat, body fat index, fat-free mass index, impedance at frequencies of 50 kHz, resistance, reactance, and phase angle were determined using the Quadscan 4000 Touch bioimpedance instrument. Appendicular skeletal muscle mass (ASMM) and muscle mass (ASMM/Ht2) were calculated. The data obtained from anthropometric and bioimpedance measurements were processed in MS Excel 2000 and STATISTICA ver. 12. The difference of means in the studied groups was tested by the t-test.

RESULTS

Presarcopenia was diagnosed in 12 (6.66%) probands out of 180 probands, of which were 3 (5%) men and 9 women (7.5%). Phase angle, ASMM and ASMM/Ht2 values were significantly lower (p < 0.001) in men and women with presarcopenia.

CONCLUSION

By introducing bioimpedance measurements into practice, it is possible to obtain results in a non-invasive way revealing possible presarcopenia in the elderly.

Osteosarcopenic Adiposity and Nutritional Status in Older Nursing Home Residents during the COVID-19 Pandemic

The aim was to evaluate body composition and prevalence of osteosarcopenic adiposity (OSA) in nursing home residents (NHR) and to assess their nutritional status. This research builds on our pilot study (conducted prior COVID-19 pandemic) that revealed high OSA prevalence and poor nutritional status in NHR. The current study included newly recruited n = 365 NHR; 296 women, 69 men, aged 84.3 ± 5.6 and 83.1 ± 7.3 years, respectively. Body composition was measured by bioelectrical impedance BIA-ACC®, yielding total bone mass along with all components of lean and adipose tissues. The Mini Nutritional Assessment-Short Form (MNA-SF) was used to assess nutritional status. Participants reported about their present/past diseases, including COVID-19. Mean duration of stay in nursing homes was 46.3 ± 47.0 months. Approximately 30% of participants had COVID-19 prior (median 6.7 months) to entering the study. OSA was diagnosed in 70.8% women and 47.8% men (p < 0.001). Malnourishment was detected in 5.8% women and 6.2% men while the risk of malnourishment was found in 30.8% women and 30.0% men. No significant differences in age, body composition parameters, prevalence of OSA, malnutrition/risk for malnutrition were found in participants who had COVID-19 compared to those who did not. Regression analysis showed that intramuscular adipose tissue (%) was significantly positively, while bone mass was significantly negatively associated with OSA. In this population, the high prevalence of OSA coincided with the high prevalence of malnutrition/risk of malnutrition. Such unfavorable body composition status is more likely a consequence of potentially poor diet quality in nursing homes, rather than of health hazards caused by COVID-19.

Ratio of extracellular water to intracellular water and simplified creatinine index as predictors of all-cause mortality for patients receiving hemodialysis

The bioelectrical impedance analysis-measured ratio of extracellular water (ECW) to intracellular water (ICW) reflects fluid volume and malnutrition. It may be an indicator of protein-energy wasting and muscle wasting in hemodialysis patients. We examined the association between the ECW/ICW ratio and simplified creatinine index, which is a new surrogate marker of protein-energy wasting and muscle wasting, and whether their combination can accurately predict mortality. A total of 224 patients undergoing hemodialysis for more than 6 months and having undergone bioelectrical impedance analysis for the assessment of body composition were included. Patients were divided into two groups based on the cut-off values of the ECW/ICW ratio (0.57) and simplified creatinine index (20.4 mg/kg/day) for maximumly predicting mortality. Thereafter, they were cross-classified into four groups with each cut-off point. The ECW/ICW ratio was independently associated with the simplified creatinine index (β = -0.164; P = 0.042). During a follow-up of 3.5 years (2.0-6.0 years), 77 patients died. A higher ECW/ICW ratio (adjusted hazard ratio, 3.66, 95% confidence interval 1.99-6.72, P <0.0001) and lower simplified creatinine index (adjusted hazard ratio, 2.25, 95% confidence interval 1.34-3.79, P = 0.0021) were independently associated with an increased risk of all-cause mortality. The adjusted hazard ratio for the higher ECW/ICW ratio and lower simplified creatinine index group vs. the lower ECW/ICW ratio and higher simplified creatinine index group was 12.22 (95% confidence interval 3.68-40.57, p <0.0001). Furthermore, the addition of the ECW/ICW ratio and simplified creatinine index to the baseline risk model significantly improved the C-index from 0.831 to 0.864 (p = 0.045). In conclusion, the ECW/ICW ratio may be a surrogate marker of muscle wasting. Moreover, combining the ECW/ICW ratio and simplified creatinine index may improve the accuracy of predicting all-cause mortality and help stratify the mortality risk of hemodialysis patients.

Predictive Roles of Basal Metabolic Rate and Body Water Distribution in Sarcopenia and Sarcopenic Obesity: The link to Carbohydrates

Sarcopenic obesity is a new category of obesity and is a specific condition of sarcopenia. This study aimed to find the relationship of the basal metabolic rate (BMR) and body water distribution with muscle health and their prospective roles in screening for sarcopenic obesity and sarcopenia. The role of nutrients such as carbohydrates in the relationship was further detected. A total of 402 elderly subjects were recruited. Body composition was estimated by bioelectrical impedance analysis. Sarcopenia was defined by the Asian Working Group for Sarcopenia 2019. The cutoff values were determined by the receiver operating characteristic curve. Mediation analyses were performed using SPSS PROCESS. Higher BMR and BMR/body surface area (BSA) were protective factors against sarcopenic obesity (OR = 0.047, p = 0.004; OR = 0.035, p = 0.002) and sarcopenia (OR = 0.085, p = 0.001; OR = 0.100, p = 0.003) in elderly people. Low extracellular water (ECW)/intracellular water (ICW) and ECW/total body water (TBW) were negatively correlated with the skeletal muscle index (SMI). The intake of dietary carbohydrates in people with sarcopenic obesity was the lowest, but in subjects with obesity, it was the highest (p = 0.023). The results of the moderated mediation model showed that BMR fully mediated the positive relationship between carbohydrates and SMI, which was more obvious in the population with an abnormal body water distribution. BMR or BMR/BSA had the potential role of predicting a higher risk of sarcopenic obesity and sarcopenia. Higher BMR and lower ECW/ICW and ECW/TBW may benefit muscle health. The overconsumption of carbohydrates (especially > AMDR) might be a risk factor for obesity. Moderate dietary carbohydrate intake might promote SMI by regulating BMR and body water distribution in the elderly.

Extracellular water-to-total body water ratio is an essential confounding factor in bioelectrical impedance analysis for sarcopenia diagnosis in women

PURPOSE

The extracellular water-to-total body water ratio (ECW/TBW) is used in bioelectrical impedance analysis (BIA) for measuring muscle mass; however, ECW/TBW may be affected by several factors common in older individuals. Here, we assessed the relationships of ECW/TBW with handgrip strength, gait speed, and skeletal muscle mass index (SMI) in older women.

METHODS

In this cross-sectional study, 73 community-dwelling women aged ≥ 65 years who could independently perform activities of daily living were included. ECW/TBW was measured using direct segmental multifrequency BIA. The participants were divided into ECW/TBW < 0.40 (n = 54) and ECW/TBW ≥ 0.40 (n = 19) groups, with the latter indicating overhydration. SMI was calculated as appendicular skeletal muscle mass/(height)² (kg/m²). The relationships of SMI with handgrip strength and gait speed were assessed using partial correlation coefficients. Age, number of medications, pain, and medical history were treated as control variables.

RESULTS

The average age of participants was 77.6 ± 6.0 years. The SMI was significantly related to handgrip strength (partial correlation coefficient = 0.293, P = 0.016) but not to gait speed (partial correlation coefficient = - 0.183, P = 0.138). Similarly, the SMI of the ECW/TBW < 0.40 group was significantly related to handgrip strength (partial correlation coefficient = 0.372, P = 0.009) but not gait speed (partial correlation coefficient = - 0.267, P = 0.066); however, the SMI of the ECW/TBW ≥ 0.40 group was not related to either variable.

CONCLUSION

ECW/TBW represents a confounding factor, which should be considered when using BIA for sarcopenia diagnosis.