Looking for Sarcopenia Biomarkers

Multidimensional Assessment of Sarcopenia and Sarcopenic Obesity in Geriatric Patients: Creatinine/Cystatin C Ratio Performs Better than Sarcopenia Index

The serum creatinine/cystatin C ratio (CCR) and the sarcopenia index (SI) are novel indicators for sarcopenia, but their accuracy may depend on various confounders. To assess CCR and SI diagnostic accuracy, we studied the clinical and biophysical parameters associated with sarcopenia or sarcopenic obesity. A total of 79 elderly patients (65-99 yrs, 33 females) underwent clinical, anthropometric, body composition, geriatric performance, and blood chemistry evaluation. The CCR and SI accuracy were assessed to identify sarcopenia. Sarcopenia was confirmed in 40.5%, and sarcopenic obesity in 8.9% of the subjects. Sarcopenic patients showed an increased Charlson comorbidity index, cardiovascular disease (CVD) rates and frailty, and decreased physical performance than non-sarcopenic subjects. Patients with sarcopenic obesity had increased body fat and inflammatory markers compared to obese subjects without sarcopenia. Sarcopenia was associated with a decreased CCR and SI. However, when the logistic regression models were adjusted for possible confounders (i.e., age, gender, Charlson comorbidity index, presence of CVD, and frailty score), a significant OR was confirmed for the CCR (OR 0.021, 95% CI 0.00055-0.83) but not for the SI. The AUC for the CCR for sarcopenia discrimination was 0.72. A higher performance was observed in patients without chronic kidney diseases (CKD, AUC 0.83). CCR, more than the SI, is a useful, non-invasive, and cost-effective tool to predict sarcopenia, irrespective of the potential confounders, particularly in subjects without CKD.

Evolving concepts on perioperative nutrition of sarcopenic cancer patients

The recent recognition of the association of sarcopenia with an increased risk of complications after a surgical procedure calls for rethinking the proper approach of the perioperative care in cancer patients. Sarcopenia is broadly considered in literature according to three different definitions: loss of muscle mass, loss of muscle mass plus reduced muscle function and myosteatosis. The aim of this short review on this issue is to define the excess of risk by type of primary and of surgical procedure, depending on the definition of sarcopenia, to speculate on this association (casual versus causal) and to examine the current therapeutical approaches. The analysis of the data shows that sarcopenia, defined as loss of muscle mass plus reduced muscle function, has the higher predictive power for the occurrence of postoperative complications than the two other definitions, and any definition of sarcopenia works better than the usual indexes or scores of surgical risk. Our analysis supports the concept that: a) sarcopenia is frequently associated with inflammation, but inflammation cannot be considered the only or the absolute cause for sarcopenia, b) sarcopenia is not a simple marker of risk but can have a direct role in the increase of risk. Data on perioperative care of sarcopenic cancer patients are scanty but a correct approach cannot rely on nutritional support alone but on a combined approach of optimized nutrition and exercise, hopefully associated with an anti-inflammatory treatment. This strategy should be applied proactively in keeping with the recent recommendations of the American Society of Clinical Oncology for the medical treatment of advanced cancer patients even if a clear demonstration of effectiveness is still lacking.

Serum Creatinine as an Independent Predictor of Moderate to Severe Fibrosis in Chinese American Non-obese Metabolic Dysfunction-Associated Steatotic Liver Disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is closely linked to the obesity epidemic. However, non-obese MASLD (body mass index [BMI] < 25 kg/m2 for Asians) is not uncommon, especially among Asian American populations. Preliminary research has demonstrated sarcopenia, a muscle-wasting syndrome, to be a major risk factor for non-obese Chinese MASLD. This study examined serum creatinine (SCr), a sarcopenia biomarker, and other prominent MASLD biomarkers for their ability to predict moderate to severe fibrosis (≥7.5 kPa or ≥F2 fibrosis) in the Chinese American MASLD population.

METHODS

A total of 296 Chinese American MASLD patients were categorized by BMI and fibrosis severity. As per World Health Organization guidelines for Asians, we identified obese MASLD (BMI ≥ 25 kg/m2) in 191 subjects (64.5%) and non-obese MASLD (BMI < 25 kg/m2) in 105 subjects (35.5%). Multivariate logistic regressions were performed to ascertain which biomarkers served as independent predictors of ≥F2 fibrosis. Wilcoxon signed-rank tests were conducted to compare MASLD cohorts (stratified by gender) and the healthy adult population on SCr distribution.

RESULTS

The obese MASLD cohorts had higher rates of ≥F2 fibrosis and type 2 diabetes mellitus compared to their older, non-obese counterparts. For obese MASLD patients, higher age (P < 0.05), increased BMI (P < 0.01), increased AST (P < 0.05), and decreased platelets (P < 0.05) independently predicted ≥F2 fibrosis. For non-obese MASLD patients, lowered SCr (P < 0.05) levels served as the main predictor of ≥F2 fibrosis. Female MASLD patients had markedly lower SCr distributions (P < 0.001) compared to the healthy female population, with 26.8% having SCr levels below the normal range.

CONCLUSIONS

In summary, SCr was the predominant predictor of moderate to severe fibrosis in non-obese Chinese American MASLD patients. The high rate of decreased SCr levels in Chinese American MASLD women suggests that this population may be at higher risk for muscle mass loss, which can lead to liver fat accumulation.

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.

Association between sarcopenia and multimorbidity among middle-aged and older adults in China: Findings from the China Health and Retirement Longitudinal Study

BACKGROUND

Little is known about the association between sarcopenia and multimorbidity among middle-aged and older adults. This study investigated whether sarcopenia is associated with multimorbidity in middle-aged and older Chinese individuals.

MATERIALS AND METHODS

A total of 12,760 participants from China Health and Retirement Longitudinal Study (CHARLS) 2015, with data on 14 specified chronic diseases and sarcopenia status were included in the cross-sectional analysis. A total of 7345 participants without multimorbidity from the CHARLS 2015 were included and followed up in 2018 in the longitudinal analysis. Logistic regression models were used in a cross-sectional investigation to assess the association between sarcopenia status and multimorbidity. In a longitudinal analysis, the relationships between sarcopenia status and multimorbidity were investigated using Cox proportional hazards models.

RESULTS

Multimorbidity was prevalent in the no sarcopenia, possible sarcopenia, and sarcopenia groups at 38.8 % (3765/9713), 56.6 % (1199/2118), and 48.5 % (451/929), respectively. Multivariable regression revealed that both possible sarcopenia (β = 0.088, P<0.001) and sarcopenia (β = 0.028, P = 0.009), contributed to the number of chronic diseases. Logistic regression revealed that possible sarcopenia (OR: 1.56, 95 % CI: 1.39-1.76) was associated with multimorbidity. In the longitudinal analysis, participants in the possible sarcopenia group (HR: 1.19, 95 % CI:1.03-1.38) were more prone to experience new onset multimorbidity than did participants in the no sarcopenia group.

CONCLUSIONS

Possible sarcopenia is associated with the development of multimorbidity in middle-aged and older Chinese populations. Health screening of populations with possible sarcopenia can facilitate early detection of multimorbidity.

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.

On variance estimation of target population created by inverse probability weighting

Inverse probability weighting (IPW) is frequently used to reduce or minimize the observed confounding in observational studies. IPW creates a pseudo-sample by weighting each individual by the inverse of the conditional probability of receiving the treatment level that he/she has actually received. In the pseudo-sample there is no variation among the multiple individuals generated by weighting the same individual in the original sample. This would reduce the variability of the data and therefore bias the variance estimate in the target population. Conventional variance estimation methods for IPW estimators generally ignore this underestimation and tend to produce biased estimates of variance. We here propose a more reasonable method that incorporates this source of variability by using parametric bootstrapping based on intra-stratum variability estimates. This approach firstly uses propensity score stratification and intra-stratum standard deviation to approximate the variability among multiple individuals generated based on a single individual whose propensity score falls within the corresponding stratum. The parametric bootstrapping is then used to incorporate the target variability by re-generating outcomes after adding a random error term to the original data. The performance of the proposed method is compared with three existing methods including the naïve model-based variance estimator, the nonparametric bootstrap variance estimator, and the robust variance estimator in the simulation section. An example of patients with sarcopenia is used to illustrate the implementation of the proposed approach. According to the results, the proposed approach has desirable statistical properties and can be easily implemented using the provided R code.

A more accurate method to estimate muscle mass: A new estimation equation

BACKGROUND

Measurement of muscle mass is important in the diagnosis of sarcopenia. Current measurement equipment are neither cost-effective nor standardized and cannot be used in a variety of medical settings. Some simple measurement tools have been proposed that are subjective and unvalidated. We aimed to develop and validate a new estimation equation in a more objective and standardized way, based on current proven variables that accurately reflect muscle mass.

METHODS

Cross-sectional analysis with The National Health and Nutrition Examination Survey database for equation development and validation. Overall, 9875 participants were included for development (6913 participants) and validation (2962 participants), for whom the database included demographic data, physical measurements, and main biochemical indicators. Appendicular skeletal muscle mass (ASM) was estimated by dual-energy x-ray absorptiometry (DXA) and low muscle mass was defined by reference to five international diagnostic criteria. Linear regression was used to estimate the logarithm of the actual ASM from demographic data, physical measurements, and biochemical indicators.

RESULTS

This study of 9875 participants comprised 4492 females (49.0%), with a weighted mean (SE) age of 41.83 (0.36) years and range of 12 to 85 years. The estimated ASM equations performed well in the validation data set. The variability in estimated ASM was low compared with the actual ASM (R2 : Equation 1 = 0.91, Equation 4 = 0.89), with low bias (median difference: Equation 1 = -0.64, Equation 4 = 0.07; root mean square error: Equation 1 = 1.70 [1.69-1.70], Equation 4 = 1.85 [1.84-1.86]), high precision (interquartile range of the differences: Equation 1 = 1.87, Equation 4 = 2.17), and high efficacy in diagnosing low muscle mass (area under the curve: Equation 1 = 0.91 to 0.95, Equation 4 = 0.90 to 0.94).

CONCLUSIONS

The estimated ASM equations are accurate and simple and can be routinely applied clinically to estimate ASM and thus assess sarcopenia.

Diagnostic Value of Serum Creatinine and Cystatin-C-Based Indices and Ishii Score in Cancer-Related Sarcopenia

BACKGROUND

Sarcopenia is a key factor affecting the prognosis of cancer patients; however, identifying patients at risk remains challenging. The serum creatinine/cystatin C ratio (CCR) and the sarcopenia index (SI) are new biomarkers for sarcopenia screening. The Ishii test score is an equation based on age, grip strength, and calf circumference for sarcopenia screening. However, their performances in advanced cancer patients have not been thoroughly studied. We aimed to evaluate and compare the accuracy of three screening tools in diagnosing cancer-related sarcopenia.

METHODS

A total of 215 cancer patients with a median age of 60.5 y were enrolled in this cross-sectional study. The Asian Working Group for Sarcopenia 2019 (AWGS2019) criteria were used as a standard. The diagnostic accuracies of the CCR, SI, and Ishii screening test were analyzed in terms of sensitivity, specificity, negative and positive predictive values, the Youden index, and the receiver operating characteristic (ROC) curve.

RESULTS

According to the AWGS2019 criteria, the prevalence of sarcopenia and severe sarcopenia was 47.9% and 18.6%, respectively. The CCR, SI (positively), and Ishii scores (negatively) were correlated with muscle mass. Accordingly, sarcopenia was negatively correlated with CCR and SI, while it was significantly positively correlated with the Ishii score. In males, the AUCs of the CCR, SI, and Ishii scores were 0.743 (95%CI 0.65-0.836), 0.758 (95%CI 0.665-0.852), and 0.833 (95%CI 0.751-0.909), respectively. In females, the AUCs of the CCR, SI, and Ishii scores were 0.714 (95%CI 0.61-0.818), 0.737 (95%CI 0.635-0.839), and 0.849 (95%CI 0.775-0.932), respectively. The AUC of the Ishii score was significantly higher than that of the other screening tools (p < 0.001). The cut-off value of the optimal Ishii score was 102.3 (sensitivity: 93.2%, specificity: 59.1%) for males and 98.3 (sensitivity: 93.3%, specificity: 64.7%) for females.

CONCLUSIONS

The CCR and SI based on serum CysC and creatinine had a remarkably similar overall diagnostic accuracy for sarcopenia in advanced cancer. Among the above three sarcopenia screening tools, the Ishii score chart seemed to have better predictive values of sarcopenia in cancer patients.

Clinically Meaningful Fatigue and Depression Are Associated with Sarcopenia in Patients with Non-Alcoholic Fatty Liver Disease

BACKGROUND

Sarcopenia is thought to be related to an increased risk of non-alcoholic steatohepatitis and advanced liver fibrosis. Our cross-sectional single-center study was designed to analyze the prevalence of sarcopenia in patients with NAFLD and possible influencing factors.

METHODS

A survey on the presence of sarcopenia, fatigue, anxiety, and depression, along with a quality-of-life (QoL) assessment, was forwarded by email to 189 outpatients. Demographics, anthropometric and clinical data (laboratory test results and abdomen complete ultrasound protocol), performed within 2-4 weeks prior to the enrollment, were obtained.

RESULTS

Sarcopenia (defined as SARC-F score ≥ 4) was identified in 17 (15.7%) patients, all of them (100%) females, with median age (interquartile range) 56 (51-64) years. These patients had a poorer metabolic state (greater values of waist and hip circumferences, body mass index, and HOMA-IR) and significantly poorer QoL, specifically, regarding the physical component of health, compared with NAFLD patients without sarcopenia. Multivariate analysis showed that depression (OR = 1.25, 95% CI: 1.02-1.53, p = 0.035) and clinically meaningful fatigue (OR = 1.14, 95% CI: 1.04-1.26, p = 0.008) were the factors independently associated with sarcopenia in patients with NAFLD.

CONCLUSION

Sarcopenia is associated with depression and fatigue rather than with the severity of liver disease alone and may negatively affect QoL in patients with NAFLD.

Impact of sarcopenia indexes on survival and severe immune acute toxicity in metastatic non-small cell lung cancer patients treated with PD-1 immune checkpoint inhibitors

BACKGROUND & AIMS

Sarcopenia has long been associated with higher toxicity induced by anti-cancer treatments and shorter survival in patients with solid tumors. The creatinine-to-cystatin ratio (CC ratio, serum creatinine/cystatin C × 100) and the sarcopenia index (SI, serum creatinine × cystatin C (CysC)-based glomerular filtration rate (eGFR_CysC)) are have been reported to be correlated with skeletal muscle mass. The aim of this study is to assess primarily whether the CC ratio and the SI could predict mortality in metastatic non-small cell lung cancer (NSCLC) patients treated with PD-1 inhibitors, and secondarily their impact on severe immune-related adverse effects (irAEs).

METHODS

From the prospective CERTIM cohort, we analyzed retrospectively stage IV NSCLC patients, who received PD-1 inhibitors between June 2015 and November 2020 in Cochin Hospital (Paris, France). We assessed sarcopenia measuring skeletal muscle area (SMA) by computed tomography and handgrip strength (HGS) by a hand dynamometer.

RESULTS

In total, 200 patients were analyzed. The CC ratio and the IS were significantly correlated with SMA and HGS: r_CC/SMA = 0.360, r_SI/SMA = 0.407, r_CC/HGS = 0.331, r_SI/HGS = 0.370. In multivariate analysis of overall survival, a lower CC ratio (HR 1.73, P = 0.033) and a lower SI (HR 1.89, P = 0.019) were independent predictors of poor prognosis. In univariate analysis of severe irAEs, CC ratio (OR 1.01, P = 0.628) and SI (OR 0.99, P = 0.595) were not associated with a higher risk of severe irAEs.

CONCLUSIONS

In metastatic NSCLC patients treated with PD-1 inhibitors, a lower CC ratio and a lower SI are independent predictors of mortality. However, they are not associated with severe irAEs.

Imaging Techniques to Determine Degree of Sarcopenia and Systemic Inflammation in Advanced Renal Cell Carcinoma

PURPOSE OF REVIEW

The purpose of this review is to provide an up-to-date understanding regarding the literature on sarcopenia and inflammation as prognostic factors in the context of renal cell carcinoma (RCC).

RECENT FINDINGS

Sarcopenia is increasingly recognized as a prognostic factor in RCC. Emerging literature suggests monitoring quantity of muscle on successive imaging and examining muscle density may be additionally informative. Inflammation has prognostic ability in RCC and is also considered a key contributor to development and progression of both RCC and sarcopenia. Recent studies suggest these two prognostic factors together may provide additional prognostic ability when used in combination. Ongoing developments include quality control regarding sarcopenia research and imaging, improving understanding of muscle loss mechanisms, and enhancing clinical incorporation of sarcopenia via improving imaging analysis practicality (i.e., artificial intelligence) and feasible biomarkers. Sarcopenia and systemic inflammation are complementary prognostic factors for adverse outcomes in patients with RCC. Further study on high-quality sarcopenia assessment standardization and expedited sarcopenia assessment is desired for eventual routine clinical incorporation of these prognostic factors.

Relationship of creatinine cystatin C ratio with muscle mass and grip strength in memory clinic outpatients

OBJECTIVES

The purpose of this study was to examine the relationship of the serum creatinine/cystatin C ratio (CCR) with hand grip strength (HGS), total body muscle mass, trunk muscle mass, and skeletal muscle mass index (SMI) in patients attending a memory clinic.

DESIGN

This cross-sectional study enrolled outpatients of a memory clinic in Japan from October 2010 to July 2017.

SETTING AND PARTICIPANTS

We enrolled 1945 participants aged 60 years or older with measured skeletal muscle mass, HGS, and serum creatinine and serum cystatin C levels.

MEASURES

Linear multiple regression analysis was performed for men and women using total body muscle mass, trunk muscle mass, and SMI as objective variables. The exposure variables were selected from previous reports if they were strongly linked to muscle mass. Total body muscle mass and trunk muscle mass were corrected by dividing by body weight. Multiple regression analysis was also conducted for men and women using HGS as an objective variable. Because cognitive function and HGS are strongly related, we also conducted sensitivity analysis by excluding participants with a Mini-Mental State Examination score < 24 to alleviate any concern that we did not fully adjust for the effect of cognitive dysfunction.

RESULTS

In men, CCR was significantly associated with total body muscle mass, trunk muscle mass, and SMI (P = 0.013, P = 0.008, and P < 0.001, respectively). In women, CCR was significantly associated with total body muscle mass and trunk muscle mass (P = 0.013 and P < 0.001, respectively), but not with SMI (P = 0.932). On the other hand, CCR was significantly associated with grip strength in both men and women (P < 0.001 and P < 0.001, respectively).

CONCLUSIONS

CCR was associated with both muscle mass and muscle strength. This study suggests that CCR is a useful marker not only for muscle mass but also for muscle strength.

Targeted proteomics of appendicular skeletal muscle mass and handgrip strength in black South Africans: a cross-sectional study

Although appendicular skeletal muscle mass (ASM) and handgrip strength (HGS) are key components of sarcopenia, their underlying biological mechanisms remain poorly understood. We aimed to investigate associations of circulating biomarkers with ASM and HGS in middle-aged black South Africans. This study consisted of 934 black South Africans (469 men and 465 women, aged 41-72 years) from the Middle-aged Soweto cohort. Linear regression models were used to examine relationships between 182 biomarkers (measured with proximity extension assay) and dual-energy X-ray absorptiometry-measured ASM and dynamometer-measured HGS. Age, height, sex, smoking, alcohol, food insecurity, physical activity, visceral adipose tissue, HIV and menopausal status were included as confounders. Regression models showing sex-interactions were stratified by sex. The Benjamini-Hochberg false discovery rate (FDR) was used to control for multiple testing, and FDR-adjusted P values were reported. In the total sample, 10 biomarkers were associated with higher ASM and 29 with lower ASM (P < 0.05). Out of these 39 biomarkers, 8 were also associated with lower HGS (P < 0.05). MMP-7 was associated with lower HGS only (P = 0.011) in the total sample. Sex-interactions (P < 0.05) were identified for 52 biomarkers for ASM, and 6 for HGS. For men, LEP, MEPE and SCF were associated with higher ASM (P < 0.001, = 0.004, = 0.006, respectively), and MEPE and SCF were also associated with higher HGS (P = 0.001, 0.012, respectively). Also in men, 37 biomarkers were associated with lower ASM (P < 0.05), with none of these being associated with lower HGS. Furthermore, DLK-1 and MYOGLOBIN were associated with higher HGS only (P = 0.004, 0.006, respectively), while GAL-9 was associated with lower HGS only (P = 0.005), among men. For women, LEP, CD163, IL6, TNF-R1 and TNF-R2 were associated with higher ASM (P < 0.001, = 0.014, = 0.027, = 0.014, = 0.048, respectively), while IGFBP-2, CTRC and RAGE were associated with lower ASM (P = 0.043, 0.001, 0.014, respectively). No biomarker was associated with HGS in women. In conclusion, most biomarkers were associated with ASM and not HGS, and the associations of biomarkers with ASM and HGS displayed sex-specificity in middle-aged black South Africans. Proteomic studies should examine ASM and HGS individually. Future research should also consider sexual dimorphism in the pathophysiology of sarcopenia for development of sex-specific treatment and diagnostic methods.

Serum creatinine and cystatin C-based diagnostic indices for sarcopenia in advanced non-small cell lung cancer

BACKGROUND

Sarcopenia is an important prognostic factor of lung cancer. The serum creatinine/cystatin C ratio (CCR) and the sarcopenia index (SI, serum creatinine × cystatin C-based glomerular filtration rate) are novel screening tools for sarcopenia; however, the diagnostic accuracy of the CCR and SI for detecting sarcopenia remains unknown. We aimed to explore and validate the diagnostic values of the CCR and SI for determining sarcopenia in non-small cell lung cancer (NSCLC) and to explore their prognostic values for overall survival.

METHODS

We conducted a prospective cohort study of adult patients with stage IIIB or IV NSCLC. Levels of serum creatinine and cystatin C were measured to calculate the CCR and SI. Sarcopenia was defined separately using CCR, SI, and the Asian Working Group for Sarcopenia (AWGS) 2019 criteria. Participants were randomly sampled into derivation and validation sets (6:4 ratio). The cutoff values for diagnosing sarcopenia were determined based on the derivation set. Diagnostic accuracy was analysed in the validation set through receiver operating characteristic (ROC) curves. Cox regression models and survival curves were applied to evaluate the impact of different sarcopenia definitions on survival.

RESULTS

We included 579 participants (women, 35.4%; mean age, 58.4 ± 8.9 years); AWGS-defined sarcopenia was found in 19.5% of men and 10.7% of women. Both CCR and SI positively correlated with computed tomography-derived and bioimpedance-derived muscle mass and handgrip strength. The optimal cutoff values for CCR and SI were 0.623 and 54.335 in men and 0.600 and 51.742 in women, with areas under the ROC curves of 0.837 [95% confidence interval (CI): 0.770-0.904] and 0.833 (95% CI: 0.765-0.901) in men (P = 0.25), and 0.808 (95% CI: 0.682-0.935) and 0.796 (95% CI: 0.668-0.924) in women (P = 0.11), respectively. The CCR achieved sensitivities and specificities of 73.0% and 93.7% in men and 85.7% and 65.7% in women, respectively; the SI achieved sensitivities and specificities of 75.7% and 86.5% in men and 92.9% and 62.9% in women, respectively. CCR-defined, SI-defined, and AWGS-defined sarcopenia were independently associated with a high mortality risk [hazard ratio (HR) = 1.75, 95% CI: 1.25-2.44; HR = 1.55, 95% CI: 1.11-2.17; and HR = 1.76, 95% CI: 1.22-2.53, respectively].

CONCLUSIONS

CCR and SI have satisfactory and comparable diagnostic accuracy and prognostic values for sarcopenia in patients with advanced NSCLC. Both may serve as surrogate biomarkers for evaluating sarcopenia in these patients. However, further external validations are required.

A combined diagnostic approach based on serum biomarkers for sarcopenia in older patients with hip fracture

OBJECTIVE

To develop prediction models for sarcopenia in older patients with hip fracture based on a specific set of serum biomarkers aimed at estimating appendicular skeletal muscle mass and diagnosing sarcopenia.

METHODS

Older patients with hip fracture admitted to the First Affiliated Hospital of Wenzhou Medical University from January 2020 to June 2021 were recruited, screened for sarcopenia and tested for peripheral blood levels of specific serum biomarkers preoperatively. Participants were randomly divided into a training set and test set. Common factors were extracted from selected biomarkers through factor analysis, and regression models were established in the training set and verified in the test set.

RESULTS

A total of 212 patients were enrolled, and the prevalence of sarcopenia was 22.8% in men and 19.5% in women. Significant differences in cystatin C, estimated glomerular filtration rate based on cystatin C, sarcopenia index, new sarcopenia index, haemoglobin and albumin were observed between patients with and without sarcopenia. Two regression models were developed in the training set. The validation of the test set confirmed that the linear regression model showed good consistency in predicting appendicular skeletal muscle mass index, while the logistic regression model showed high accuracy in predicting sarcopenia.

CONCLUSIONS

Both prediction models exhibited potential clinical application value for estimating appendicular skeletal muscle mass and predicting sarcopenia in older patients with hip fracture, providing new insights into the serological diagnosis of sarcopenia.

A Novel Application of Serum Creatinine and Cystatin C to Predict Sarcopenia in Advanced CKD

Sarcopenia is highly prevalent in patients with advanced chronic kidney disease (CKD), yet a reliable serum index has not been established. The product of serum creatinine and the estimated glomerular filtration rate based on cystatin C (Cr×eGFRcys) was recently proposed as a sarcopenia index (SI), approximately to 24-h filtered creatinine through the glomerulus. We aimed to evaluate the diagnostic validity of the novel SI in advanced CKD. In 297 patients with non-dialysis stage 3b-5 CKD, aged 68.8 ± 12.9 years, the total skeletal muscle mass (SMM), handgrip strength (HGS), and usual gait speed were assessed. Sarcopenia was defined based on the Asian Working Group for Sarcopenia 2019 consensus update. The prevalence of sarcopenia in this cohort was 20.2%. The SI correlated moderately with SMM (r = 0.503, P &lt; 0.001), HGS (r = 0.508, P &lt; 0.001), and gait speed (r = 0.381, P &lt; 0.001); the independency of the SI with three muscle metrics was confirmed after extensive adjustment. For sarcopenia prediction, the SI had acceptable discriminative powers in males [area under the receiver operating characteristic curve (AUC) 0.646, 95% confidence interval (CI) 0.569–0.718] and females (AUC 0.754, 95% CI 0.670–0.826). In males, the best cut-off was 53.9, which provided 71.1% sensitivity, 58.0% specificity, 32.9% positive predictive value (PPV), and 87.4% negative predictive value (NPV); in females, the best cut-off was 45.8, which provided 81.8% sensitivity, 62.3% specificity, 31.0% PPV, and 94.3% NPV. In conclusion, Cr×eGFRcys could be served as a surrogate marker for sarcopenia and may be helpful for sarcopenia screening in advanced CKD. Further studies are needed to expand our investigation.

Serum indices based on creatinine and cystatin C predict mortality in patients with non-dialysis chronic kidney disease

Serum indices based on creatinine and cystatin C, including creatinine/cystatin C ratio (Cr/CysC), ratio and difference of estimated glomerular filtration rate (eGFR) based on cystatin C and creatinine (eGFRcys/eGFRcre and eGFR_Diff), and serum creatinine × eGFRcys, are recently identified serum markers for sarcopenia. We aimed to evaluate the association between these serum indices and mortality in patients with chronic kidney disease (CKD). A single-center retrospective cohort study included 1141 adult patients with stage 1–5 CKD between 2016 and 2018. Basic characteristics, comorbidities, laboratory parameters, and serum creatinine and cystatin C values were obtained. Patients were followed up until death, dialysis, transfer to another hospital, or end of the study. The median age (interquartile range) of our participants was 71 (62–81) years. During a median follow-up of 39 months, 116 (10.2%) patients died. Compared to the survivor group, Cr/CysC, eGFRcys/eGFRcre, eGFR_Diff, and Cr × eGFRcys were all lower in the non-survivors (p < 0.001 for all). The receiver operating characteristic curves of serum indices for predicting mortality showed that all four indices had significant discriminative power. Based on the Cox proportional hazard models, lower values of four serum indices, both as continuous and categorical variables, independently predicted mortality. Our findings suggest that low serum indices of Cr/CysC, eGFRcys/eGFRcre, eGFRDiff, and Cr × eGFRcys are independent indicators of mortality in patients with non-dialysis CKD.

Muscle, endocrine, and immunological markers of frailty in older people

OBJECTIVE

To analyze muscle, endocrine, and immunological markers that influence frailty in older people assisted in primary care.

MATERIALS AND METHODS

Cross-sectional, analytical, and probabilistic study were linked to the institutional research "Integrated Health Care for Older People." The study population consisted of males and females aged 60 years or more and assisted in primary health care. The research protocol included an interview and physical examination to evaluate the frailty criteria. Analysis of the following were done: serum calcium and creatinine as muscle markers; vitamin D, parathyroid hormone, and insulin-like growth factor - 1 as endocrine markers; and interleukin-6, C-reactive protein, leukocytes, and neutrophil-lymphocyte ratio as immunological markers. Statistical analysis included the Mann-Whitney test to compare means, and linear regression to analyze the relationship between dependent and independent variables.

RESULTS

There was a relationship between creatinine and prediction of weight loss (p < 0.001), leukocytes and prediction of handgrip strength (p = 0.022), interleukin-6 and prediction of energy expenditure (p = 0.026), and vitamin D and prediction of gait time (p = 0.036). Also, sex influenced handgrip strength (p < 0.001), and age influenced handgrip strength (p < 0.001), gait time (p < 0.001) and energy expenditure (p < 0.001).

CONCLUSION

The joint use of muscle, endocrine, and immunological markers may be useful to diagnose frailty and to propose resolutive interventions to reduce negative outcomes for older people.

Effects of multi-domain lifestyle interventions on sarcopenia measures and blood biomarkers: secondary analysis of a randomized controlled trial of community-dwelling pre-frail and frail older adults

Few studies have comprehensively described changes in blood biomarkers of the physiological responses underlying sarcopenia reduction associated with lifestyle interventions. In this study, we performed secondary analyses of data in a randomized controlled trial of multi-domain lifestyle interventions (6-month duration physical exercise, nutritional enrichment, cognitive training, combination and standard care control) among 246 community-dwelling pre-frail and frail elderly, aged ≥65 years, with and without sarcopenia. Appendicular lean mass (ALM), lower limb strength, gait speed, and blood levels of markers of muscle metabolism, inflammation, anti-oxidation, anabolic hormone regulation, insulin signaling, tissue oxygenation were measured at baseline, 3-month and 6-month post-intervention. Multi-domain interventions were associated with significant (p < 0.001) reduction of sarcopenia at 3-month and 6-month post-intervention, improved gait speed, enhanced lower limb strength, and were equally evident among sarcopenic participants who were slower at baseline than non-sarcopenic participants. Active intervention was associated with significantly reduced inflammation levels. Sarcopenia status and reduction were associated with blood biomarkers related to muscle metabolism, steroid hormone regulation, insulin-leptin signaling, and tissue oxygenation. Physical, nutritional and cognitive intervention was associated with measures of sarcopenia reduction, together with changes in circulating biomarkers of anabolic and catabolic metabolism underlying sarcopenia.

Towards Personalized Management of Sarcopenia in COPD

The awareness of the presence and consequences of sarcopenia has significantly increased over the past decade. Sarcopenia is defined as gradual loss of muscle mass and strength and ultimately loss of physical performance associated with aging and chronic disease. The prevalence of sarcopenia is higher in chronic obstructive pulmonary disease (COPD) compared to age-matched controls. Current literature suggests that next to physical inactivity, COPD-specific alterations in physiological processes contribute to accelerated development of sarcopenia. Sarcopenia in COPD can be assessed according to current guidelines, but during physical performance testing, ventilatory limitation should be considered. Treatment of muscle impairment can halt or even reverse sarcopenia, despite respiratory impairment. Exercise training and protein supplementation are currently at the basis of sarcopenia treatment. Furthermore, effective current and new interventions targeting the pulmonary system (eg, smoking cessation, bronchodilators and lung volume reduction surgery) may also facilitate muscle maintenance. Better understanding of disease-specific pathophysiological mechanisms involved in the accelerated development of sarcopenia in COPD will provide new leads to refine nutritional, exercise and physical activity interventions and develop pharmacological co-interventions.

A review of the incorporation of QDs and imprinting technology in optical sensors – imprinting methods and sensing responses

This review aims to cover the simultaneous method of using molecularly imprinted technology and quantum dots (QDs) as well as its application in the field of optical sensors.

Nutritional Biomarkers and Associated Factors in Community-Dwelling Older Adults: Findings from the SHIELD Study

Aging is associated with intrinsic and extrinsic changes which affect the nutrient intake and nutritional status of an older individual. Suboptimal nutritional status is linked with adverse health outcomes. There are limited data in this area for community-dwelling older adults who are not at risk of malnutrition. The objective of this study was to describe the nutritional biomarkers in 400 community-dwelling older adults (aged ≥65 years) with normal nutritional status (Malnutrition Universal Screening Test score of 0) in Singapore and to identify factors associated with these biomarkers. The majority of the participants had normal levels of pre-albumin, albumin, total protein, creatinine, zinc, corrected calcium, vitamin B12, ferritin and hemoglobin. Females had significantly higher levels of corrected calcium and vitamin B12 than males, whereas males had significantly higher levels of pre-albumin, albumin, creatinine, serum ferritin, 25-hydroxyvitamin D (25(OH)D) and hemoglobin than females. About half of the participants (52%) had low level of 25(OH)D (<30 μg/L) and 10% had low zinc level (<724 μg/L). Among those with low level of 25(OH)D, 74% had 25(OH)D insufficiency (20–<30 μg/L) and 26% had 25(OH)D deficiency (<20 μg/L). Younger age, female gender, non-Chinese ethnicity and no intake of vitamin D supplement were associated with lower serum 25(OH)D level, whereas higher body mass index (BMI) was associated with low zinc level. These findings highlight the problem of hidden nutritional insufficiencies can be missed in seemingly normal nourished community-dwelling older adults.

A new index based on serum creatinine and cystatin C is useful for assessing sarcopenia in patients with advanced cancer

OBJECTIVES

Sarcopenia is a well-known risk factor for inferior cancer outcomes, but the identification of patients at risk remains challenging. A new sarcopenia index (SI), defined as serum creatinine (Cr) × cystatin C (CysC)-based glomerular filtration rate (eGFR_CysC), has been reported to be an objective surrogate marker for sarcopenia. The aim of this study was to assess whether the SI is associated with sarcopenia and cancer-related fatigue (CRF) in patients with advanced cancer.

METHODS

This cross-sectional study included 182 patients with different types of cancer (cancer stages III/IV; mean age 55.1 ± 11.1 y). Sarcopenia was defined as the presence of both low muscle mass and low muscle strength. The cross-sectional area of skeletal muscle mass (SMA) at the third lumbar spine was estimated by computed tomography (CT). Low muscle mass was defined as a skeletal muscle index (SMA/height²) <34.9 cm²/m² for women and 40.8 cm²/m² for men. Low muscle strength was determined by handgrip strength (HGS) according to the cutoffs of the Asian Working Group for Sarcopenia (<18 kg for women and <26 kg for men). CRF was measured by the Brief Fatigue Inventory (BFI). The associations between SI with both sarcopenia and CRF were investigated.

RESULTS

The prevalence of sarcopenia was 27.5%. The SI was significantly lower in both the sarcopenia and severe fatigue groups. The associations between SI and SMA (r = 0.365; P < 0.001), skeletal muscle index (SMI) (r = 0.340; P < 0.001), and HGS (r = 0.414; P <0 .001) were stronger than the associations between the serum creatinine/cystatin C (Cr/CysC) ratio and SMA (r = 0.299; P < 0.001), SMI (r = 0.269; P <0 .001), and HGS (r = 0.364; P <0 .001). Additionally, a decrease in the SI was associated with a higher likelihood of sarcopenia (odds ratio per 10-unit, 1.09; 95% confidence interval, 1.02-1.16) after adjusting for potential confounding factors. However, there was only a weak correlation between the SI and BFI score (r = -0.161, P = 0.045).

CONCLUSION

The SI might be a useful objective tool for assessing sarcopenia in patients with advanced cancer. Further studies are warranted to extend the present findings.

Serum creatinine/cystatin C ratio as a case-finding tool for low handgrip strength in Chinese middle-aged and older adults

Measuring handgrip strength is the initial step to diagnose sarcopenia. To investigate whether the serum creatinine (Cr)/cystatin C (CysC) ratio could serve as a case-finding tool for low handgrip strength, we conducted a diagnostic accuracy study. Adults (aged ≥ 40 years) with normal renal function were recruited. Trained nurses collected blood samples and conducted the anthropometric measurements and handgrip strength test. The serum concentrations of Cr, CysC, and other biomarkers were measured. We recruited 1098 men and 1241 women. The Cr/CysC ratio was significantly associated with AWGS-defined low handgrip strength among men and women. The areas under the receiver operating characteristic curves were 0.79 among men and 0.78 among women for using the Cr/CysC ratio to identify AWGS-defined low handgrip strength. We set the Cr/CysC ratio cut-off values at < 8.9 among men and < 8.0 among women. The corresponding sensitivity values were 64.9% among men and 63.1% among women, while the specificity values were 83.7% among men and 77.5% among women. In conclusion, the Cr/CysC ratio is positively and linearly associated with handgrip strength and may be helpful for screening low handgrip strength in Chinese middle-aged and older adults dwelling in communities.

A new diagnostic index for sarcopenia and its association with short-term postoperative complications in patients undergoing surgery for colorectal cancer

AIM

Sarcopenia is a robust prognostic indicator of outcomes after surgery for colorectal cancer (CRC). However, there are no serum markers routinely available for estimating skeletal muscle mass (SMM). The present study aimed to describe a new sarcopenia index (SI), serum creatinine (Scr) × cystatin C-based glomerular filtration rate, and investigate its association with short-term complications after curative resection of CRC.

METHOD

Consecutive patients who underwent curative resection of CRC from December 2011 to January 2017 were retrospectively identified. Skeletal muscle cross-sectional area was analysed on L3 computed tomographic images. Receiver operating characteristic curve analysis showed that the cutoff points of SI for sarcopenia were below 56.1 in men and below 43.7 in women. Patients were classified into low and high SI groups in accordance with these cutoff values. The association between SI and body composition and the impact of preoperative SI on postoperative outcomes were analysed.

RESULTS

Among 417 patients, SI showed a stronger correlation with skeletal muscle area (SMA) (r = 0.537, P < 0.001) than with the Scr/cystatin C ratio (r = 0.469, P < 0.001) and Scr (r = 0.447, P < 0.001). The low SI group had a lower SMA, lower preoperative haemoglobin, a higher prevalence of sarcopenia and experienced more postoperative complications compared with the high SI group (all P < 0.001). Multivariate logistic regression analysis showed that the independent risk factors for overall complications were low preoperative haemoglobin, low SI, sarcopenia and American Society of Anesthesiologists grade ≥ 3.

CONCLUSION

This new SI is a simple and useful surrogate marker for estimating SMM, and is associated with outcomes after CRC surgery.

Sarcopenia

Sarcopenia is defined as a combination of low muscle mass with low muscle function. The term was first used to designate the loss of muscle mass and performance associated with aging. Now, recognized causes of sarcopenia also include chronic disease, a physically inactive lifestyle, loss of mobility, and malnutrition. Sarcopenia should be differentiated from cachexia, which is characterized not only by low muscle mass but also by weight loss and anorexia. Sarcopenia results from complex and interdependent pathophysiological mechanisms that include aging, physical inactivity, neuromuscular compromise, resistance to postprandial anabolism, insulin resistance, lipotoxicity, endocrine factors, oxidative stress, mitochondrial dysfunction, and inflammation. The prevalence of sarcopenia ranges from 3% to 24% depending on the diagnostic criteria used and increases with age. Among patients with rheumatoid arthritis 20% to 30% have sarcopenia, which correlates with disease severity. Sarcopenia exacts a heavy toll of functional impairment, metabolic disorders, morbidity, mortality, and healthcare costs. Thus, the consequences of sarcopenia include disability, quality of life impairments, falls, osteoporosis, dyslipidemia, an increased cardiovascular risk, metabolic syndrome, and immunosuppression. The adverse effects of sarcopenia are particularly great in patients with a high fat mass, a condition known as sarcopenic obesity. The diagnosis of sarcopenia rests on muscle mass measurements and on functional tests that evaluate either muscle strength or physical performance (walking, balance). No specific biomarkers have been identified to date. The management of sarcopenia requires a multimodal approach combining a sufficient intake of high-quality protein and fatty acids, physical exercise, and antiinflammatory medications. Selective androgen receptor modulators and anti-myostatin antibodies are being evaluated as potential stimulators of muscle anabolism.