Estimation of Muscle Mass Using Creatinine/Cystatin C Ratio in Japanese Community-Dwelling Older People

The association between the cystatin C- and creatinine-based estimated GFR ratio and post-ablation outcomes in patients with atrial fibrillation

BACKGROUND

The difference between the cystatin C-based eGFR (eGFRcys) and the creatinine-based eGFR (eGFRcr) is associated with the risk of developing atrial fibrillation (AF) risk. However, its impact on AF ablation outcomes is unknown.

METHODS

The associations between the baseline eGFR ratio (eGFRcys/eGFRcr) and the risk of experiencing post-ablation endpoints were evaluated on a continuous scale (restricted cubic splines) and by a priori defined centile categories with Cox proportional hazards regression models. The primary endpoints were AF recurrence and adverse events; the secondary endpoint was rehospitalization.

RESULTS

Among 989 participants (49.2% women; mean age 65.7 years), 313 experienced AF recurrence after a median follow-up of 28 months. After full adjustment for confounding factors, a U-shaped association was observed between eGFR ratio and AF recurrence risk (minimum risk at 0.797). Although a U-shaped trend was observed, there was no statistically significant association between the eGFR ratio and adverse events or rehospitalization. Hazard ratios for AF recurrence, compared to the second quartile, were 1.68 (1.20-2.37) for the first quartile, 1.64 (1.15-2.34) for the third quartile, and 1.96 (1.37-2.80) for the fourth quartile. According to the subgroup analysis, the above association was strongly U-shaped for males and linear for females.

CONCLUSION

In the AF population, both low and high eGFR ratios were associated with an increased risk of post-ablation AF recurrence.

Predictive value of creatinine-cystatin C ratio for mortality and technique failure in anuric peritoneal dialysis patients

OBJECTIVES

Both serum creatinine and cystatin C serve as dependable markers of renal function and have demonstrated a correlation with clinical outcomes in diverse conditions, particularly through the ratio of creatinine to cystatin C (Cr/CysC). Anuric patients undergoing peritoneal dialysis (PD) depend entirely on the clearance of peritoneal solutes. This research posits that the Cr/CysC ratio may predict all-cause mortality and technique failure in anuric PD patients.

METHODS

A cohort of 224 anuric PD patients was recruited from January 1, 2014, to December 31, 2019, with follow-up extending until December 31, 2023. The Cr/CysC ratio was computed by dividing the serum creatinine concentration by the cystatin C concentration obtained on the same day. We evaluated the relationship between the Cr/CysC ratio and patient survival, as well as technique failure, utilizing Cox regression and competing risk analyses.

RESULTS

The average age of the participants was 50.46 ± 12.63 years, with 99 individuals (44.2%) being male. Among all subjects, the Cr/CysC ratio was found to be 1.85 ± 0.56. After controlling for potential confounders, Cox proportional hazards models revealed that the Cr/CysC ratio was significantly linked to the risk of all-cause mortality and technique failure (HR = 0.330, 95% CI 0.124-0.881, p = 0.027; HR = 0.440, 95% CI 0.267-0.726, p = 0.002). Importantly, the significant associations observed in the Cox regression analysis persisted even after accounting for competing risks.

CONCLUSION

The Cr/CysC ratio at baseline was recognized as an independent predictor of all-cause mortality and technique failure in anuric PD patients.

From a Solitary Blood-Derived Biomarker to Combined Biomarkers of Sarcopenia: Experiences From the Korean Frailty and Aging Cohort Study

Sarcopenia is recognized as a complex and multifactorial disorder that includes nutritional deficiency, inactivity, proinflammatory status, hormonal changes, neurological degeneration, and metabolic disturbances. It's pathogenesis is not fully understood. Therefore, identifying specific biomarkers of sarcopenia will help us understand its pathophysiology. The most frequently reported blood-derived biomarkers of sarcopenia are growth factors, neuromuscular junctions, endocrine systems, mitochondrial dysfunction, inflammation-mediated and redox processes, muscle protein turnover, blood metabolomics, and behavior-mediated biomarkers. Here, we address the implications of sarcopenia biomarkers based on our research experience with Korean Frailty and Aging Cohort Study cohort data. It includes free testosterone, myostatin, fibroblast growth factor 21 (FGF-21), growth differentiation factor 15 (GDF-15), procollagen type III N-terminal peptide (P3NP), creatinine-based biomarkers, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), brain-derived neurotrophic factor (BDNF), metabolites (proline, alanine, tryptophan), and multi-biomarker risk score. We attempted to explain the paradoxical findings of myostatin and FGF-21 levels in relation to sarcopenia. GDF-15 levels were associated with sarcopenia prevalence but not its incidence. Plasma P3NP and BDNF levels may be biomarkers of muscle quality rather than quantity. Lower erythrocyte eicosapentaenoic acid (EPA) and docosahexaenoic acid levels were associated with slow gait speed, and erythrocyte EPA levels were associated with low handgrip strength. We developed a multi-biomarker risk score for sarcopenia and found that its accuracy in diagnosing sarcopenia was higher than that of any single biomarker.

Normalized Creatinine-to-Cystatin C Ratio and Risk of Cardiometabolic Multimorbidity in Middle-Aged and Older Adults: Insights from the China Health and Retirement Longitudinal Study

BACKGRUOUND

Normalized creatinine-to-cystatin C ratio (NCCR) was reported to approximate relative skeletal muscle mass and diabetes risk. However, the association between NCCR and cardiometabolic multimorbidity (CMM) remains elusive. This study aimed to explore their relationship in a large-scale prospective cohort.

METHODS

This study included 5,849 middle-age and older participants from the China Health and Retirement Longitudinal Study (CHARLS) enrolled between 2011 and 2012. The baseline NCCR was determined as creatinine (mg/dL)/cystatin C (mg/L)×10/body mass (kg). CMM was defined as the simultaneous occurrence of two or more of the following conditions: heart disease, stroke, and type 2 diabetes mellitus. Logistic regression analysis and Cox regression analysis were employed to estimate the relationship between NCCR and CMM. The joint effect of body mass index and NCCR on the risk of CMM were further analyzed.

RESULTS

During a median 4-year follow-up, 227 (3.9%) participants developed CMM. The risk of CMM was significantly decreased with per standard deviation increase of NCCR (odds ratio, 0.72; 95% confidence interval, 0.62 to 0.85) after adjustment for confounders (P<0.001). Further sex-specific analysis found significant negative associations between NCCR and CMM in female either without or with one CMM component at baseline, which was attenuated in males but remained statistically significant among those with one basal CMM component. Notably, non-obese individuals with high NCCR levels had the lowest CMM risk compared to obese counterparts with low NCCR levels in both genders.

CONCLUSION

High NCCR was independently associated with reduced risk of CMM in middle-aged and older adults in China, particularly females.

Low creatinine to cystatin C ratio is associated with lower muscle volumes and poorer gait speeds in the longitudinal Integrated Women's Health Program cohort

OBJECTIVE

Little is known about the longitudinal associations between creatinine-cystatin C ratios (CCR) with muscle volume and function during the menopausal transition. We investigated the longitudinal relationship of baseline CCR, with muscle volumes measured by magnetic resonance imaging (MRI), and objectively measured muscle strength and physical performance after 6.6-year follow-up.

METHODS

Participants from the Integrated Women's Health Programme (IWHP) cohort (n = 891, baseline mean age 56.2 ± 6.0) who attended both baseline and follow-up visits underwent objectively measured muscle strength and physical performance assessments and MRI. Creatinine to cystatin C ratio was calculated as (creatinine [mg/dL] / cystatin C [mg/L]) and low CCR were those in the lowest tertile (CCR < 8.16). Multivariable regression analyses were used to determine the associations of baseline CCR with muscle volumes and function 6.6 years later.

RESULTS

Baseline low CCR was associated with lower MRI-measured muscle volumes and poorer physical function 6.6 years later. Compared to high CCR group, mean fat-free thigh muscle volume of the low CCR group was 0.350 L lower (95% CI, 0.183-0.518) after adjustment for covariates. Similarly, the low CCR group was associated with 0.029 m/s slower (95% CI, 0.006-0.053) slower mean usual gait and 0.049 m/s slower (95% CI, 0.020-0.078) mean narrow gait speeds. CCR was not associated with handgrip strength and repeated chair stands and one-leg stand tests.

CONCLUSION

Low CCR at baseline was associated with lower fat-free muscle volumes and poorer gait speeds 6.6 years later. The potential of CCR as a predictive biomarker for adverse events related to sarcopenia in midlife women merits further investigation.

Association between skeletal muscle mass and the prognosis of patients undergoing percutaneous coronary intervention: a retrospective study

BACKGROUND

The predicted skeletal muscle mass index (pSMI) is a proven and reliable index that reflects muscle mass; however, its ability to predict major adverse cardiovascular events (MACES) in patients with coronary artery disease (CAD) undergoing percutaneous coronary intervention (PCI) remains uncertain.

METHODS

A total of 1340 enrolled patients were ultimately included in the study and stratified according to the pSMI tertiles. The primary endpoint was a complex set of MACEs, including all-cause mortality, nonfatal myocardial infarction, and unplanned revascularization. The Kaplan‒Meier method was used to generate a cumulative incidence curve of MACEs and secondary endpoint events of all-cause mortality. Due to the competing risk relationship between all-cause mortality and cardiovascular mortality, non-fatal myocardial infarction, and unplanned revascularization events, a competing risk model was employed to analyze the cumulative event incidence curves of competing risk events.The restricted cubic spline analysis was conducted to examine the linear association between pSMI and the incidence of MACE. A univariate and multivariate Cox regression model was utilized to identify predictors of MACEs. The predictive value of the pSMI was evaluated by determining the area under the ROC curve.

RESULTS

During a median follow-up of 31.38 months, 217 patients developed MACEs. The Kaplan-Meier survival curve showed the lowest risk of MACEs and all-cause mortality in the high pSMI group(log-rank test, P < 0.05). After adjusting for competing risk factors for all-cause death, the cumulative events of cardiac death in the T3 group were lower than other two groups (Gray's test, P < 0.001), with no significant difference in the cumulative incidence of non-fatal myocardial infarction and unplanned revascularization between the pSMI groups (Gray's test, P > 0.05). The adjusted hazard ratio (HR) for the incidence of MACEs in the highest pSMI tertile was 0.335(95% CI 0.182-0.615; P < 0.001), as shown by multivariable Cox regression analysis. Subgroup analysis revealed that the pSMI was negatively correlated with the incidence of MACEs in a population of nonelderly individuals, and those without heart failure (all P < 0.05). Both the univariate and fully adjusted restriction cubic spline (RCS) curves showed a linear relationship between the pSMI and MACEs. In addition, the inclusion of the pSMI in the basic risk prediction model improved prognostic prediction (the area under the ROC curve increased from 0.647 to 0.682, P = 0.033).

CONCLUSION

In patients with CAD undergoing PCI, the pSMI is a protective factor and potentially simple method for assessing the risk of MACEs independently.

CLINICAL TRIAL NUMBER

Not applicable.

Sex differences in the association between sarcopenia index and sarcopenia: a cross-sectional study from a Chinese community-based population

PURPOSE

The sarcopenia index (SI) is a convenient method to screen for sarcopenia, but few studies have analysed whether there are sex differences. The aim of this study was to analyse sex differences in the relationship between SI and sarcopenia in a Chinese community-based population.

METHODS

This cross-sectional study included participants from 2011 China Health and Retirement Longitudinal Study. The SI was defined as 100 × creatinine / cystatin C. Diagnosis of sarcopenia based on the Asian Working Group for Sarcopenia 2019 consensus. Logistic regression model, linear regression model, and natural spline model were used to analyze the association between SI and sarcopenia.

RESULTS

A total of 7,118 participants with a mean age of 60.6 ± 10.1 were included, 53.4% females. In males, the prevalence of sarcopenia decreased by 25% for every 10 increase in SI, and skeletal muscle mass index (SMI) increased by 0.04, odds ratio (OR), β, and 95% confidence interval (CI) were 0.75 (0.65-0.87), 0.04 (0.02-0.05), both P < 0.001. In females, the SI was not significantly associated with sarcopenia, OR and 95% CI were 0.99 (0.9 ~ 1.08), P = 0.775; for every 10 increase in SI, the SMI in females decreased by 0.03, β and 95% CI were -0.03 (-0.04 ~ -0.01), P = 0.001.

CONCLUSION

In the Chinese community, the SI is negatively associated with sarcopenia in males and has moderate diagnostic test performance. It was not associated with sarcopenia in females, and using the SI to screen for sarcopenia in females may not be a reliable method.

Oral Frailty and Its Relationship with Physical Frailty in Older Adults: A Longitudinal Study Using the Oral Frailty Five-Item Checklist

BACKGROUND/OBJECTIVES

Oral frailty, first identified in Japan in 2014, refers to a state between healthy oral function and severe decline, marked by minor issues, such as tooth loss and chewing difficulties. The oral frailty five-item checklist (OF-5) enables non-dental professionals to evaluate oral frailty using five key indicators: remaining teeth count, chewing difficulties, swallowing difficulties, dry mouth, and articulatory oral skills. Limited studies exist.

METHODS

This study examined the relationship between oral and physical frailties in older adults and assessed the prognosis of physical frailty using the OF-5. Participants aged ≥65 years were recruited from the frail elderly in the Sasayama-Tamba area, Hyogo, Japan, and their physical function was assessed in terms of grip strength, walking speed, and skeletal muscle mass. Blood markers, such as cystatin C, an indicator of renal function, were also analyzed.

RESULTS

A cross-sectional analysis indicated that oral frailty was correlated with reduced muscle mass, walking speed, and physical function. Women had lower hemoglobin and albumin levels and a greater prevalence of frailty than men. Longitudinal analysis revealed that initial OF-5 scores predicted increased physical frailty after 2-3 years, especially in those with higher baseline scores. The OF-5 was a significant factor for frailty progression in both sexes.

CONCLUSIONS

These results suggest that early detection of oral frailty via the OF-5 may be useful in preventing the progression of overall frailty in older adults.

Diagnostic Power of Serum Creatinine/Cystatin C Ratio for Identifying Low MRI-Muscle Volume and Low Grip Strength: Data From 9 731 to 149 707 UK Biobank Older Adults

BACKGROUND

Biomarkers for sarcopenia are lacking. We examined the diagnostic power of serum creatinine to cystatin C ratio for identifying low magnetic resonance imaging-muscle volume and low grip strength in a large observational study of UK Biobank older adults.

METHODS

Serum creatinine and cystatin C were measured via immunoassays (Beckman Coulter AU5800 and Siemens Advia 1800, respectively) and grip strength by hydraulic hand dynamometer at baseline visit (2008-2010). magnetic resonance imaging-thigh fat-free muscle volume and DXA-derived appendicular lean mass were measured at imaging visit (2014-2018). Extreme outliers were removed, and covariates (demographic, lifestyle, and clinical factors, as well as time elapsed between baseline-imaging visit) were adjusted for in statistical models.

RESULTS

12 873 older adults (mean age: 63.5 ± 2.7 years, 44.2% women) were included for fat-free muscle volume and appendicular lean mass/body mass index; 149 707 older adults (mean age: 64.0 ± 2.9 years, 50.5% women) for grip strength. Despite significant associations (p < .05), in fully adjusted models, creatinine to cystatin C showed poor to acceptable diagnostic power for identifying low fat-free muscle volume when using cutpoints of 20th percentile (area under the curve: 0.577 men; 0.622 women) and T scores of -2 (area under the curve: 0.596 men; 0.659 women) and -2.5 (area under the curve: 0.609 men; 0.722 women). In fully adjusted model, creatinine to cystatin C showed poor diagnostic power (area under the curves: <0.70) for identifying low appendicular lean mass/body mass index or low grip strength, irrespective of the cutpoint used.

CONCLUSIONS

Creatinine to cystatin C may not be a suitable biomarker for identifying low muscle volume or low strength in older adults. This finding, drawn from a large sample size and the use of advanced medical imaging, marks an important contribution to the sarcopenia field.

Serum creatinine- and cystatin C-based indices are associated with the risk of subsequent sarcopenia: evidence from the China Health and Retirement Longitudinal Study

Background

Serum creatinine (Cr)- and cystatin C (CysC)-based indices have been suggested as alternative markers for sarcopenia, but their predictive value for sarcopenia risk is uncertain, which was investigated in the present study in the Chinese population with the middle and older ages.

Methods

Data from the China Health and Retirement Longitudinal Study (CHARLS) were collected in the 2011 and 2015 waves. All participants were free of sarcopenia at the baseline. Sarcopenia was diagnosed when low muscle mass and grip strength or low physical performance were present. Four indices were computed: predictive skeletal muscle mass index (pSMI), total-body muscle mass (TBMM), creatinine-to-cystatin C ratio (CCR), and sarcopenia index (SI). Restricted cubic splines and logistic regression models were used to assess the effects of these indices on sarcopenia risk.

Results

Among 4,527 participants without sarcopenia at the baseline (2011), the median age was 58 year-old (IQR: 52-65), with 52.7% women. Followed up in year 2015, the incidence of sarcopenia was 20.8 per 1,000 person-years (376/4,527). Neither CCR nor SI showed linear or non-linear associations with the risk of subsequent sarcopenia. However, a decrease in pSMI and TBMM was significantly associated with an increased risk of sarcopenia [adjusted per-SD decrease OR, 2.93; 95% CI, 2.09-4.13, p < 0.001; adjusted per-SD decrease OR: 2.38, 95% CI: 1.80-3.16, p < 0.001, respectively].

Conclusion

In the middle and older age of Chinese population, decreased pSMI and TBMM were associated with an increased risk of subsequent sarcopenia, whereas CCR and SI showed no such correlation. Thus, pSMI and TBMM may serve as potential biological indicators for predicting the risk of sarcopenia, and decreased pSMI and TBMM may be the early biomarkers for diagnosis and intervention of sarcopenia.

Creatinine-to-cystatin C ratio and frailty in older adults: a longitudinal cohort study

BACKGROUND

Creatinine-to-cystatin C ratio (CCR) has been associated with multiple adverse outcomes. However, little is known about its relationship with frailty. We aimed to explore the association between CCR and frailty among older adults.

METHODS

A total of 2599 participants aged ≥ 60 years (mean age 67.9 ± 6.0 years, 50.4% males) were included from the China Health and Retirement Longitudinal Study (2011-2015). Baseline CCR was calculated as plasma creatinine (mg/dL) / cystatin C (mg/L) × 10 and was grouped by quartiles. Frailty was evaluated by the validated physical frailty phenotype (PFP) scale and was defined as PFP score ≥ 3. The generalized estimating equations model was used to explore the relationship between CCR and frailty.

RESULTS

The frailty risk decreased gradually with increasing CCR in the quartiles (P for trend = 0.002), and the fourth CCR quartile was associated with a significantly lower risk of frailty compared with the lowest quartile (odds ratio [OR] 0.37, 95% confidence interval [CI] 0.19-0.70). When modeling as a continuous variable, per 1-unit increase in CCR was related to 17% decreased odds of frailty (OR 0.83, 95% CI 0.74-0.93). The association was consistent in male and female participants (P for interaction = 0.41). Poisson models revealed that frailty score was negatively associated with CCR (β= -0.11, 95% CI= -0.19 to -0.04), and sex did not significantly moderate the associations (P for interaction = 0.22). The results were not affected by further adjusting for high-sensitivity C-reactive protein. Similar results were observed by analyses with multiple imputation technique and analyses excluding participants with baseline frailty.

CONCLUSIONS

Higher CCR was associated with a lower frailty risk. CCR may be a simple marker for predicting frailty in older adults.

Serum creatinine and serum cystatin C as an index of muscle mass in adults

PURPOSE OF REVIEW

Serum creatinine reflects both muscle mass and kidney function. Serum cystatin C has recently been recommended as an additional marker for estimating kidney function, and use of both markers together may provide an index of muscle mass. This review aims to describe the biological basis for and recent research examining the relationship of these markers to muscle mass in a range of adult populations and settings.

RECENT FINDINGS

This review identified 67 studies, 50 of which had direct measures of muscle mass, and almost all found relationships between serum creatinine and cystatin C and muscle mass and related outcomes. Most studies have been performed in older adults, but similar associations were found in general populations as well as in subgroups with cancer, chronic kidney disease (CKD), and other morbid conditions. Creatinine to cystatin C ratio was the measure examined the most often, but other measures showed similar associations across studies.

SUMMARY

Measures of serum creatinine and cystatin C together can be an index of muscle mass. They are simple and reliable measures that can be used in clinical practice and research. Further study is needed to determine actionable threshold values for each measure and clinical utility of testing and intervention.

Sex difference in the association between creatinine-to-cystatin C ratio and metabolic syndrome among Chinese adults

Background

Metabolic syndrome (MetS), characterized by central obesity, insulin resistance, dyslipidemia, and hypertension, affects 20-25% of the global population. The creatinine-to-cystatin C ratio (CCR) is an indicator of skeletal muscle mass. While CCR may play a role in MetS development, sex differences in these associations are not fully understood. Therefore, this study aimed to investigate how CCR levels are associated with MetS in a Chinese adult population, focusing on possible sex disparities.

Method

We conducted a retrospective cross-sectional analysis of 9,376 adults from Xiamen Chang Gung Hospital between 2014 to 2016. We examined the relationship between CCR and MetS, adjusting for cardiometabolic risk factors.

Results

The prevalence of MetS was 24.7% in males and 18.0% in females. Interestingly, we observed significant sex differences in the association between CCR quartiles and MetS. Females in the lowest CCR quartile had a significantly higher risk of MetS (odds ratio=1.84). Receiver operating characteristic curve analysis revealed acceptable diagnostic power of CCR for MetS in females (area under the curve=0.65) but not in males.

Conclusion

Our findings suggest that CCR is an independent risk factor for MetS in females, highlighting the importance of sex-specific assessments when evaluating MetS risk.

Usefulness of the serum creatinine/cystatin C ratio as a blood biomarker for sarcopenia components among age groups in community-dwelling older people: The SONIC study

AIM

The serum creatinine/cystatin C ratio (CCR) or sarcopenia index is considered a useful marker of muscle mass. However, its usefulness in late-stage older adults remains unclear. We aimed to determine the usefulness of CCR as an indicator of sarcopenia in community-dwelling Japanese adults aged >75 years.

METHODS

Our study recruited participants aged 70, 80, and 90 ± 1 years during the baseline years, and included a 3-year follow-up in the Septuagenarians, Octogenarians, Nonagenarians, Investigation with Centenarians study. From 2015 to 2018, 955 participants were eligible: 367 in their 70s, 304 in their 80s, and 284 in their 90s. The diagnostic components of sarcopenia, including "low muscle mass, plus low muscle strength, and/or low physical performance," were evaluated using the bioelectrical impedance analysis-measured skeletal muscle mass index (SMI), handgrip strength, and short physical performance battery (SPPB) score, respectively, in accordance with the Asia Working Group for Sarcopenia 2019 criteria. Separate analyses were performed between each component and CCR, adjusting for sex, body mass index, and other blood biomarkers in each group.

RESULTS

The relationship between CCR and sarcopenia components was significant for handgrip strength (β = 0.21, 0.13, 0.19, and P < 0.0001, =0.0088, <0.0001, for the 70s, 80s, and 90s age groups, respectively); however, it was limited for SMI (β = 0.14; P = 0.0022, only for the 90s) and not significant for the SPPB score.

CONCLUSION

CCR is a limited indicator of sarcopenia in late-stage older adults. Although its association with muscle strength was significant, its relationship with muscle mass and physical performance was less pronounced. Geriatr Gerontol Int 2024; 24: 529-536.

Effects of short-term moderate intensity exercise on the serum metabolome in older adults: a pilot randomized controlled trial

BACKGROUND

We previously reported changes in the serum metabolome associated with impaired myocardial relaxation in an asymptomatic older community cohort. In this prospective parallel-group randomized control pilot trial, we subjected community adults without cardiovascular disease to exercise intervention and evaluated the effects on serum metabolomics.

METHODS

Between February 2019 to November 2019, thirty (83% females) middle-aged adults (53 ± 4 years) were randomized with sex stratification to either twelve weeks of moderate-intensity exercise training (Intervention) (n = 15) or Control (n = 15). The Intervention group underwent once-weekly aerobic and strength training sessions for 60 min each in a dedicated cardiac exercise laboratory for twelve weeks (ClinicalTrials.gov: NCT03617653). Serial measurements were taken pre- and post-intervention, including serum sampling for metabolomic analyses.

RESULTS

Twenty-nine adults completed the study (Intervention n = 14; Control n = 15). Long-chain acylcarnitine C20:2-OH/C18:2-DC was reduced in the Intervention group by a magnitude of 0.714 but increased in the Control group by a magnitude of 1.742 (mean difference -1.028 age-adjusted p = 0.004). Among Controls, alanine correlated with left ventricular mass index (r = 0.529, age-adjusted p = 0.018) while aspartate correlated with Lateral e' (r = -764, age-adjusted p = 0.016). C20:3 correlated with E/e' ratio fold-change in the Intervention group (r = -0.653, age-adjusted p = 0.004). Among Controls, C20:2/C18:2 (r = 0.795, age-adjusted p = 0.005) and C20:2-OH/C18:2-DC fold-change (r = 0.742, age-adjusted p = 0.030) correlated with change in E/A ratio.

CONCLUSIONS

Corresponding relationships between serum metabolites and cardiac function in response to exercise intervention provided pilot observations. Future investigations into cellular fuel oxidation or central carbon metabolism pathways that jointly impact the heart and related metabolic systems may be critical in preventive trials.

Sex-specific associations between skeletal muscle mass and incident diabetes: A population-based cohort study

AIMS

To investigate the sex-specific associations between predicted skeletal muscle mass index (pSMI) and incident type 2 diabetes in a retrospective longitudinal cohort of Chinese men and women.

MATERIALS AND METHODS

We enrolled Chinese adults without diabetes at baseline from WATCH (West chinA adulT health CoHort), a large health check-up-based database. We calculated pSMI to estimate skeletal muscular mass, and measured blood glucose variables and assessed self-reported history to identify new-onset diabetes. The nonlinear association between pSMI and incident type 2 diabetes was modelled using the penalized spline method. The piecewise association was estimated using segmented linear splines in weighted Cox proportional hazards regression models.

RESULTS

Of 47 885 adults (53.2% women) with a median age of 40 years, 1836 developed type 2 diabetes after a 5-year median follow-up. In women, higher pSMI was associated with a lower risk of incident type 2 diabetes (Pnonlinearity  = 0.09, hazard ratio [HR] per standard deviation increment in pSMI: 0.79 [95% confidence interval {CI} 0.68, 0.91]). A nonlinear association of pSMI with incident type 2 diabetes was detected in men (Pnonlinearity  < 0.001). In men with pSMI lower than 8.1, higher pSMI was associated with a lower risk of incident type 2 diabetes (HR 0.58 [95% CI 0.40, 0.84]), whereas pSMI was not significantly associated with incident diabetes in men with pSMI equal to or greater than 8.1 (HR 1.08 [95% CI 0.93, 1.25]).

CONCLUSIONS

In females, a larger muscular mass is associated with a lower risk of type 2 diabetes. For males, this association is significant only among those with diminished muscle mass.

Diagnostic test accuracy of serum creatinine and cystatin C-based index for sarcopenia: a systematic review and meta-analysis

BACKGROUND

Sarcopenia is an important prognostic factor, but its optimal screening methods remain challenging. Several new indices developed based on serum creatinine (Cr) and cystatin C (CysC) have been proposed to be diagnostic biomarkers for sarcopenia screening.

OBJECTIVE

This review aimed to evaluate the diagnostic accuracy of serum Cr- and CysC-based indices for sarcopenia diagnosis.

METHODS

We systematically searched MEDLINE, EMBASE, SCIE and SCOPUS from inception to 2 April 2023. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. A bivariate random-effects model was used to synthesise the pooled sensitivity, specificity and area under the curves of the summary receiver operating characteristic (SROC-AUC).

RESULTS

We retrieved 936 publications and included 16 studies with 5,566 participants (mean age ranged: 51.0-78.4 years, 50.2% men). The prevalence of sarcopenia ranged from 7.8 to 69.5%. All included studies presented a moderate to high risk of bias. The serum Cr- and CysC-based indices showed moderate diagnostic accuracy for sarcopenia (pooled sensitivity: 0.67, 95% CI 0.57-0.75; pooled specificity: 076, 95% CI 0.67-0.83; pooled SROC-AUC: 0.78, 95% CI 0.74-0.81). The Cr/CysC ratio is the most widely studied index, followed by the Cr × eGFRcys index. Overall, both indicators had satisfactory and comparable performance in screening sarcopenia.

CONCLUSION

Serum Cr- and CysC-based indices showed moderate diagnostic accuracy for sarcopenia. The most studied indices-the Cr/CysC ratio and Cr × eGFRcys index-had comparable diagnostic accuracy for evaluating sarcopenia and may serve as surrogate markers for sarcopenia. However, further validation is required to verify these findings.

Blood biomarkers for sarcopenia: A systematic review and meta-analysis of diagnostic test accuracy studies

Biomarkers are emerging as a potential tool for screening or diagnosing sarcopenia. We aimed to summarize the current evidence on the diagnostic test accuracy of biomarkers for sarcopenia. We comprehensively searched Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials up to January 2023 and only included diagnostic test accuracy studies. We identified 32 studies with 23,840 participants (women, 58.26%) that assessed a total of 30 biomarkers. The serum creatinine to cystatin C ratio (Cr/CysC) demonstrated a pooled sensitivity ranging from 51% (95% confidence interval [CI] 44-59%) to 86% (95% CI 70-95%) and a pooled specificity ranged from 55% (95% CI 38-70%) to 76% (95% CI 63-86%) for diagnosing sarcopenia defined by five different diagnostic criteria (11 studies, 7240 participants). The aspartate aminotransferase to alanine aminotransferase ratio demonstrated a pooled sensitivity of 62% (95% CI 56-67%) and a pooled specificity of 66% (95% CI 60-72%) (3 studies, 11,146 participants). The other 28 blood biomarkers exhibited low-to-moderate diagnostic accuracy for sarcopenia regardless of the reference standards. In conclusion, none of these biomarkers are optimal for screening or diagnosing sarcopenia. Well-designed studies are needed to explore and validate novel biomarkers for sarcopenia.

Comparison of the serum creatinine- and cystatin-C-based indices as screening biomarkers for sarcopenia in community-dwelling older adults

BACKGROUND

Several creatinine- and cystatin-C-based indices have been proposed as sarcopenia predictors. This study aimed to compare serum creatinine- and cystatin-C-based indices as screening biomarkers for sarcopenia in community-dwelling older adults.

METHODS

A cross-sectional study was conducted on 945 participants aged between 70 and 84 years (men=47.5%; mean age=76.0 ± 3.9 years) from the Korean Frailty and Aging Cohort Study. The serum creatinine-to-cystatin-C ratio estimated glomerular filtration rate (eGFR) ratio (eGFRcystatin-C/eGFRcreatinine), sarcopenia index (serum creatinine × eGFRcreatinine), predicted skeletal muscle mass index (pSMI), and total body muscle mass index (TBMM) were compared.

RESULTS

The prevalence of sarcopenia was 19.9% in men and 14.0% in women. The pSMI and TBMM showed higher correlations with appendicular lean mass and grip strength in men (pSMI: rs=0.356-0.701, p < 0.001; TBMM: rs=0.320-0.730, p < 0.001) and women (pSMI: rs=0.299-0.669, p < 0.001; TBMM: rs=0.256-0.658, p < 0.001) than the other indices. The area under the receiver operating characteristic curves (AUC) of the serum indices for predicting sarcopenia showed the highest accuracy for pSMI (men: AUC=0.77, p < 0.001; women: AUC=0.71, p < 0.001). After adjusting for potential confounders, pSMI was associated with the likelihood of sarcopenia in both men (odds ratio [OR]=0.170; 95% confidence interval [CI]=0.103-0.279) and women (OR=0.167; 95% CI=0.087-0.321).

CONCLUSION

pSMI and TBMM accurately determined sarcopenia than the other indices. Furthermore, a higher pSMI was strongly associated with a decreased risk of sarcopenia compared to TBMM. These findings suggest pSMI as a potential biomarker for sarcopenia screening in community-dwelling older adults.

Muscle mass, creatinine, cystatin C and selective glomerular hypofiltration syndromes

In this issue of Clinical Kidney Journal, Stehlé and colleagues demonstrate that estimation of glomerular filtration rate (GFR) by use of creatinine and a measure, total lumbar muscle cross-sectional area, reflecting the total muscle mass of an individual, is superior to GFR-estimating equations based upon creatinine and demographic variables. The report by Stehlé et al. demonstrates one solution to the interference of muscle mass in the use of creatinine to estimate GFR. This interference was identified already at the start, in 1959, of using creatinine for estimation of GFR. Different ways of taking the muscle mass into account when creatinine-based estimations of GFR have been used generally include use of controversial race and sex coefficients. A new marker of GFR, cystatin C, introduced in 1979, has been shown to be virtually uninfluenced by muscle mass. In this editorial, the simultaneous use of creatinine and cystatin C to estimate GFR, muscle mass and selective glomerular hypofiltration syndromes is described.

The complexity of kidney disease and diagnosing it - cystatin C, selective glomerular hypofiltration syndromes and proteome regulation

Estimation of kidney function is often part of daily clinical practice, mostly done by using the endogenous glomerular filtration rate (GFR)-markers creatinine or cystatin C. A recommendation to use both markers in parallel in 2010 has resulted in new knowledge concerning the pathophysiology of kidney disorders by the identification of a new set of kidney disorders, selective glomerular hypofiltration syndromes. These syndromes, connected to strong increases in mortality and morbidity, are characterized by a selective reduction in the glomerular filtration of 5-30 kDa molecules, such as cystatin C, compared to the filtration of small molecules <1 kDa dominating the glomerular filtrate, for example water, urea and creatinine. At least two types of such disorders, shrunken or elongated pore syndrome, are possible according to the pore model for glomerular filtration. Selective glomerular hypofiltration syndromes are prevalent in investigated populations, and patients with these syndromes often display normal measured GFR or creatinine-based GFR-estimates. The syndromes are characterized by proteomic changes promoting the development of atherosclerosis, indicating antibodies and specific receptor-blocking substances as possible new treatment modalities. Presently, the KDIGO guidelines for diagnosing kidney disorders do not recommend cystatin C as a general marker of kidney function and will therefore not allow the identification of a considerable number of patients with selective glomerular hypofiltration syndromes. Furthermore, as cystatin C is uninfluenced by muscle mass, diet or variations in tubular secretion and cystatin C-based GFR-estimation equations do not require controversial race or sex terms, it is obvious that cystatin C should be a part of future KDIGO guidelines.

Belt Electrode-Skeletal Muscle Electrical Stimulation in Older Hemodialysis Patients with Reduced Physical Activity: A Randomized Controlled Pilot Study

Background: Although patients receiving hemodialysis are more likely to develop metabolic disorders and muscle weakness at an earlier stage than healthy individuals, many older dialysis patients have difficulty establishing exercise habits to prevent these problems. Therefore, we evaluated the use of belt electrode-skeletal muscle electrical stimulation (B-SES), which can stimulate a wider area than conventional electrical muscle stimulation (EMS), to examine its application and safety in older hemodialysis patients as a means to improve lower extremity function without voluntary effort. Methods: This study was a randomized controlled trial (RCT) involving 20 older dialysis patients (>65 years old) with reduced physical activity. The control group received 12 weeks of routine care only and the intervention group received 12 weeks of B-SES during hemodialysis in addition to routine care. The primary endpoint was the 6 min walk test (6MWT) distance, while the Short Physical Performance Battery (SPPB), body composition, Functional Independence Measure (FIM), biochemistry test, and blood pressure/pulse measurements were used as secondary endpoints. Results: As a result of the 12-week B-SES intervention, no increase in creatine kinase or C-reactive protein levels was observed after the intervention in either group, and no adverse events attributed to the B-SES intervention were observed in the intervention group. Furthermore, the intervention group showed a significant improvement in the 6MWT and SPPB scores after the intervention. Conclusions: The results of this study suggest that a 12-week B-SES intervention during hemodialysis sessions safely improves 6MWT distance and SPPB scores in older patients with a reduced level of physical activity.

Relationships between cystatin C and creatinine‐based eGFR with low tongue pressure in Japanese rural community‐dwelling older adults

Background

Sarcopenia is prevalent in patients with chronic kidney disease (CKD), which is defined as a low estimated glomerular filtration rate (eGFR). It has been reported that oral hypofunction characterized by decreased tongue pressure is related to sarcopenia. Although there are several previous reports regarding the association of renal dysfunction with oral hypofunction characterized by low tongue pressure, the association between tongue pressure and renal function is not fully understood.

Methods

This cross‐sectional study included 68 men aged 79.0 ± 4.8 years and 145 women aged 77.3 ± 5.4 years from a rural area in Hyogo Prefecture, Japan. We examined the relationships between cystatin C‐based CKD (CKDcys), creatinine‐based CKD (CKDcre), ratio of cystatin C‐based GFR (eGFRcys) divided by creatinine‐based GFR (eGFRcre): eGFRcys/eGFRcre, and tongue pressure in community‐dwelling older adults.

Results

Tongue pressure was significantly lower in participants with CKDcys than in those without CKDcys in men and women. However, there were no significant differences in tongue pressure with or without CKDcre. Tongue pressure was significantly lower in participants with eGFRcys/eGFRcre <1.0, than in those with eGFRcys/eGFRcre ≧ 1.0 in men. According to the receiver operating characteristic analysis, the optimal cut‐off value of tongue pressure for the presence of CKDcys was 36.6kPa, area under the curve (AUC) 0.74 (specificity 54.8%, sensitivity 84.6%) in men and 31.8kPa, AUC 0.65 (specificity 67.3%, sensitivity 60.5%) in women.

Conclusions

CKDcys but not CKDcre is associated with low tongue pressure. In addition, a lower eGFRcys/eGFRcre ratio is a useful screening marker of low tongue pressure in community‐dwelling older adults.

Cystatin C-based equations for estimating glomerular filtration rate do not require race or sex coefficients

Estimation or measurement of glomerular filtration rate (GFR) is generally required for optimal treatment of patients. Plasma creatinine has been used for estimation of GFR since 1926 and plasma cystatin C since 1979. The creatinine level is strongly dependent upon muscle mass and as the average muscle mass of different populations may vary, creatinine-based GFR-estimating equations have since 1999 used more than 10 different race coefficients to improve the diagnostic performance of such equations. But 'race' cannot be determined by biological measurements and is thus an ill-defined biological entity and controversial as it involves self-reporting and social considerations. In contrast, cystatin C-levels are virtually independent of muscular mass and cystatin C-based GFR-estimating equations do not require race coefficients for reliable estimation of GFR. The use of cystatin C-based GFR-estimating equations, alone or in conjunction with creatinine-based GFR-estimating equations, is therefore highly recommended to eliminate the use of race coefficients in estimating GFR. Although sex is a more biology-oriented parameter than race, sex terms may in some cases be controversial, involving self-reporting and social considerations. However, sex terms are not required for adequate estimation of GFR using cystatin C-based equations.