Association between muscle strength and advanced fibrosis in non-alcoholic fatty liver disease: a Korean nationwide survey

Association of muscle mass, grip strength and fat-to-muscle ratio and metabolic dysfunction-associated steatotic liver disease in a middle-to-elderly aged population

OBJECTIVE

The association of appendicular skeletal muscle mass (ASM), grip strength and fat-to-muscle ratio (FMR) and the progression of metabolic dysfunction-associated steatotic liver disease (MASLD) are not well known.

MATERIALS AND METHODS

This study included participants older than 40 years who underwent bioelectrical impedance assessment in Prevalence of Metabolic Diseases and Risk Factors in Shunde (SPEED-Shunde). We measured grip strength with an electronic grip strength metre. ASM and grip strength were adjusted by dividing body mass index (BMI). FMR was calculated as total fat mass to total muscle mass. Liver steatosis and liver fibrosis were evaluated by vibration-controlled transient elastography. Multifactorial logistic regression was used to analyse the relationship between ASM, grip strength, FMR, and MASLD or MASLD-associated liver fibrosis. We performed subgroup analyses according to sex, age and BMI. Interaction tests and linear trend tests were also conducted.

RESULTS

This study included a total of 3277 participants. FMR was positively associated with MASLD (OR: 1.89, 95% CI: 1.66-2.15) and MASLD-associated liver fibrosis (OR: 1.70, 95% CI: 1.22-2.37). While ASM/BMI (OR: 0.59, 95% CI: 0.52-0.67) or grip strength/BMI (OR: 0.72, 95% CI: 0.66-0.78) were negatively associated with MASLD. Interactions were observed between ASM/BMI and age, grip strength and sex in MASLD, as well as FMR and MASLD-associated liver fibrosis.

CONCLUSION

In a middle-to-elderly aged population, FMR was positively associated with the risk of MASLD and MASLD-associated liver fibrosis, and muscle mass and grip strength were negatively associated with MASLD, rather than MASLD-associated liver fibrosis.

A Precision Medicine Guided Approach to the Utilization of Biomarkers in MASLD

The new nomenclature of metabolic dysfunction-associated steatotic liver disease (MASLD) emphasizes a positive diagnosis based on cardiometabolic risk factors. This definition is not only less stigmatizing but also allows for subclassification and stratification, thereby addressing the heterogeneity of what was historically referred to as nonalcoholic fatty liver disease. The heterogeneity within this spectrum is influenced by several factors which include but are not limited to demographic/dietary factors, the amount of alcohol use and drinking patterns, metabolic status, gut microbiome, genetic predisposition together with epigenetic factors. The net effect of this dynamic and intricate system-level interaction is reflected in the phenotypic presentation of MASLD. Therefore, the application of precision medicine in this scenario aims at complex phenotyping with consequent individual risk prediction, development of individualized preventive strategies, and improvements in the clinical trial designs. In this review, we aim to highlight the importance of precision medicine approaches in MASLD, including the use of novel biomarkers of disease, and its subsequent utilization in future study designs.

The prevalence and effects of sarcopenia in patients with metabolic dysfunction-associated steatotic liver disease (MASLD): A systematic review and meta-analysis

BACKGROUND AND AIMS

Sarcopenia is a common complication in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). However, the prevalence and its impact on the survival of sarcopenia in patients with MASLD is unknown. In this study, we aimed to assess the prevalence and effects of sarcopenia in patients with MASLD.

METHODS

Systematic review and meta-analysis of full texts of relevant studies were searched from inception until June 12, 2024 in five databases (PubMed, Cochrane Library, Embase, Web of Science, and the China National Knowledge Infrastructure). Next, we assessed the prevalence of sarcopenia in MASLD, and calculated the ORs and HRs between sarcopenia and MASLD based on the adjusted data from individual studies. Statistical analyses were performed using Stata 11.0.

RESULTS

Of the 2984 records considered, 29 studies recruiting 63,330 patients were included. The pooled prevalence of sarcopenia in patients with MASLD was 23.5% overall (95% CI; 19.1%-27.9%, I2 = 99.6%), and was higher in Asian patients, male, cross-sectional studies, when BIA were employed to measure muscle mass, one criterion of diagnosis sarcopenia, MASLD was diagnosed employing MRI, and moderate-quality studies. Sarcopenia was associated with MASLD patients (adjusted odds ratio [aOR] 2.08, 95% CI 1.58-2.74, I2 = 93.6%) with similar findings in subgroups stratified by age, study design, methods for measuring muscle mass, assessment method to detect sarcopenia, and study quality. The association between all-cause mortality further supports the association between sarcopenia and poor prognosis with MASLD (aHR 1.59, 95% CI 1.33-1.91, I2 = 0%).

CONCLUSIONS

Sarcopenia was strongly associated with MASLD progression and was a risk factor not only for MASLD pathogenesis but was also markedly correlated with MASLD-associated mortality.

Effectiveness of the ALT/AST ratio for predicting insulin resistance in a Korean population: A large-scale, cross-sectional cohort study

Insulin resistance is a common pathophysiology in patients with type 2 diabetes mellitus, cardiovascular disease, and non-alcoholic fatty liver disease. Thus, screening for the risk of insulin resistance is important to prevent disease progression. We evaluated the alanine aminotransferase/aspartate aminotransferase (ALT/AST) ratio to predict insulin resistance in the general population, regardless of comorbidities. Datasets from the 2015, 2019, and 2020 Korea National Health and Nutrition Examination Surveys were used, and the following four indices were implemented to indicate insulin resistance: fasting serum glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), and β-cell function. We analyzed the degree of association between the liver enzyme profile and insulin resistance indices using Pearson's correlation coefficient and determined the associations using linear or logistic regression analysis. Accordingly, ALT levels in both sexes were positively and consistently correlated with the four aforementioned insulin resistance indices in stratification analyses based on diabetes, dyslipidemia, alcohol consumption, and obesity status. In multivariate linear regression, when comparing with ALT levels, the ALT/AST ratio exhibited superior predictive performance for fasting serum glucose and HOMA-β in Korean men and improved outcomes for all insulin resistance indices in Korean women. In this analysis that included a large community-based population, the ALT/AST ratio was a more useful predictive marker than the HOMA-IR. Regarding the predicted presence or absence of insulin resistance, the ALT/AST ratio could better predict HOMA-IR than the ALT level alone in Koreans. A simple, precise marker that represents the ALT/AST ratio could be a practical method to screen for insulin resistance in the general population, regardless of diabetes mellitus, alcohol intake, and sex.

Prevalence and outcome of sarcopenia in non-alcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) includes a spectrum of conditions, progressing from mild steatosis to advanced fibrosis. Sarcopenia, characterized by decreased muscle strength and mass, shares common pathophysiological traits with NAFLD. An association exists between sarcopenia and increased NAFLD prevalence. However, data on the prevalence of sarcopenia in NAFLD and its impact on the outcomes of NAFLD remain inconsistent.

AIM

To analyze the prevalence and outcomes of sarcopenia in patients with NAFLD.

METHODS

We conducted a comprehensive search for relevant studies in MEDLINE, Embase, and Scopus from their inception to June 2023. We included studies that focused on patients with NAFLD, reported the prevalence of sarcopenia as the primary outcome, and examined secondary outcomes, such as liver fibrosis and other adverse events. We also used the Newcastle-Ottawa scale for quality assessment.

RESULTS

Of the 29 studies included, the prevalence of sarcopenia in NAFLD varied widely (1.6% to 63.0%), with 20 studies reporting a prevalence of more than 10.0%. Substantial heterogeneity was noted in the measurement modalities for sarcopenia. Sarcopenia was associated with a higher risk of advanced fibrosis (odd ratio: 1.97, 95% confidence interval: 1.44-2.70). Increased odds were consistently observed in fibrosis assessment through biopsy, NAFLD fibrosis score/body mass index, aspartate aminotransferase to alanine aminotransferase ratio, diabetes (BARD) score, and transient elastography, whereas the fibrosis-4 score showed no such association. Sarcopenia in NAFLD was associated with a higher risk of steatohepatitis, insulin resistance, cardiovascular risks, and mortality.

CONCLUSION

This systematic review highlights the critical need for standardized diagnostic criteria and measurement methods for sarcopenia in NAFLD patients. The variability in study designs and assessment methods for sarcopenia and liver fibrosis may account for the inconsistent findings. This review demonstrates the multidimensional impact of sarcopenia on NAFLD, indicating its importance beyond liver-related events to include cardiovascular risks, mortality, and metabolic complications.

Metabolic-associated fatty liver disease and sarcopenia: A double whammy

The prevalence of metabolic-associated fatty liver disease (MAFLD) has increased substantially in recent years because of the global obesity pandemic. MAFLD, now recognized as the number one cause of chronic liver disease in the world, not only increases liver-related morbidity and mortality among sufferers but also worsens the complications associated with other comorbid conditions such as cardiovascular disease, type 2 diabetes mellitus, obstructive sleep apnoea, lipid disorders and sarcopenia. Understanding the interplay between MAFLD and these comorbidities is important to design optimal therapeutic strategies. Sarcopenia can be either part of the disease process that results in MAFLD (e.g., obesity or adiposity) or a consequence of MAFLD, especially in the advanced stages such as fibrosis and cirrhosis. Sarcopenia can also worsen MAFLD by reducing exercise capacity and by the production of various muscle-related chemical factors. Therefore, it is crucial to thoroughly understand how we deal with these diseases, especially when they coexist. We explore the pathobiological interlinks between MAFLD and sarcopenia in this comprehensive clinical update review article and propose evidence-based therapeutic strategies to enhance patient care.

Muscle strength and non-alcoholic fatty liver disease/metabolic-associated fatty liver disease

This editorial comments on an article published in a recent issue of World Journal of Gastroenterology, entitled “Association of low muscle strength with metabolic dysfunction-associated fatty liver disease: A nationwide study”. We focused on the association between muscle strength and the incidence of non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD), as well as the mechanisms underlying the correlation and related clinical applications. NAFLD, which is now redefined as MAFLD, is one of the most common chronic liver diseases globally with an increasing prevalence and is characterized by malnutrition, which may contribute to decreased muscle strength. Reduction of muscle strength reportedly has a pathogenesis similar to that of NAFLD/ MAFLD, including insulin resistance, inflammation, sedentary behavior, as well as insufficient vitamin D. Multiple studies have focused on the relationship between sarcopenia or muscle strength and NAFLD. However, studies investigating the relationship between muscle strength and MAFLD are limited. Owing to the shortage of specific medications for NAFLD/MAFLD treatment, early detection is essential. Furthermore, the relationship between muscle strength and NAFLD/MAFLD suggests that improvements in muscle strength may have an impact on disease prevention and may provide novel insights into treatments including dietary therapy, as well as tailored physical activity.

Association of low muscle strength with metabolic dysfunction-associated fatty liver disease: A nationwide study

BACKGROUND

There is limited evidence regarding the association between muscle strength and metabolic dysfunction-associated fatty liver disease (MAFLD).

AIM

To investigate the association between muscle strength and MAFLD in the general population in Korea.

METHODS

This nationwide representative cross-sectional study included 31649 individuals aged ≥ 19 years who participated in the Korea National Health and Nutrition Examination Survey between 2015 and 2018. Odds ratios (ORs) and 95% confidence intervals (95%CIs) for MAFLD according to sex-specific quartiles of muscle strength, defined by relative handgrip strength, were calculated using multivariable logistic regression analysis. Additionally, multivariable logistic regression analysis was used to assess the association between muscle strength and probable liver fibrosis in patients with MAFLD.

RESULTS

Of all the participants, 29.3% had MAFLD. The prevalence of MAFLD was significantly higher in the lower muscle strength quartile groups for all participants, sexes, and age groups (P < 0.001). A 1.92-fold (OR = 1.92, 95%CI: 1.70-2.16) and 3.12-fold (OR = 3.12, 95%CI: 2.64-3.69) higher risk of MAFLD was observed in the lowest quartile (Q1) group than in the other groups (Q2-Q4) and the highest quartile (Q4) group, respectively. The ORs of MAFLD were significantly increased in the lower muscle strength quartile groups in a dose-dependent manner (P for trend < 0.001). These associations persisted in both sexes. An inverse association between muscle strength and the risk of MAFLD was observed in all subgroups according to age, obesity, and diabetes mellitus. In patients with MAFLD, the odds of severe liver fibrosis were higher in Q1 (OR = 1.83, 95%CI: 1.25-2.69) than in other groups (Q2-Q4).

CONCLUSION

Among Korean adults, low muscle strength was associated with an increased risk of MAFLD and liver fibrosis in patients with MAFLD.

Association between handgrip strength, nonalcoholic fatty liver disease, advanced hepatic fibrosis and its modifiers: Evidence from the NHANES database of the USA

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) and advanced hepatic fibrosis (AHF) have been associated with sarcopenia. However, modifiers of this association have been less studied.

METHODS

This study used data from the NHANES database 2011-2014 of the USA. Adults aged 18 years or older, had complete information of handgrip strength test and NAFLD and AHF status were eligible for inclusion. NAFLD was defined using the Fatty Liver Index (FLI). AHF was defined using the NAFLD fibrosis score (NFS). Univariate and multivariate logistic regression were performed to determine the associations between the study variables and prevalent NAFLD and AHF.

RESULTS

A total of 19 931 participants were selected from the 2011-2014 NHANES database. The multivariate analysis showed that stronger grip strength was significantly and independently associated with decreased odds for NAFLD (tertile 2: adjusted odd ratio [aOR]: 0.41, 95% confidence interval [CI]: 0.29-0.59; tertile 3: aOR: 0.11, 95% CI: 0.05-0.24) and AHF (tertile 2: aOR: 0.66, 95% CI: 0.46-0.94; tertile 3: aOR: 0.28, 95% CI: 0.12-0.63). In stratified analyses, strongest grip strength was significantly associated with reduced odds for NAFLD regardless of age, body mass index, and having diabetes or not. Strongest grip strength was associated with reduced odds for NAFLD in individuals who had moderate to ideal physical activity (aOR: 0.31).

CONCLUSIONS

Grip strength has an inverse association with prevalent NAFLD and AHF in the US population, which appears to be modified by physical activity level. Future prospective cohort studies are needed to clarify the role of physical activity in modifying the risks.

Sarcopenia Among Patients With Nonalcoholic Fatty Liver Disease (NAFLD) Is Associated With Advanced Fibrosis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) and sarcopenia can be associated with advanced liver disease. Our aim was to assess the association between sarcopenia and the risk of fibrosis among patients with NAFLD.

METHODS

We used the National Health and Nutrition Examination Survey (2017-2018). NAFLD was defined by transient elastography without other causes of liver disease or excessive alcohol use. Significant fibrosis (SF) and advanced fibrosis (AF) were defined by liver stiffness greater than 8.0 kPa and greater than 13.1 kPa, respectively. Sarcopenia was defined using the Foundation for the National Institutes of Health definition.

RESULTS

Of the total cohort (N = 2422), 18.9% had sarcopenia, 9.8% had obese sarcopenia, 43.6% had NAFLD, 7.0% had SF, and 2.0% had AF. Moreover, 50.1% had neither sarcopenia nor NAFLD, 6.3% had sarcopenia without NAFLD, 31.1% had NAFLD without sarcopenia, and 12.5% had NAFLD with sarcopenia. Compared with individuals without NAFLD or sarcopenia, individuals with sarcopenic NAFLD had higher rates of SF (18.3% vs 3.2%) and AF (7.1% vs 0.2%). In the absence of sarcopenia, compared with individuals without NAFLD, individuals with NAFLD have a significantly increased risk of SF (odds ratio, 2.18; 95% CI, 0.92-5.19). In the presence of sarcopenia, NAFLD was associated with an increased risk of SF (odds ratio, 11.27; 95% CI, 2.79-45.56). This increase was independent of metabolic components. The proportion of SF that is attributable to the interaction of NAFLD and sarcopenia was 55% (attributable proportion, 0.55; 95% CI, 0.36-0.74). Increased leisure time physical activity was associated with a lower risk of sarcopenia.

CONCLUSIONS

Patients with sarcopenic NAFLD are at risk for SF and AF. Increased physical activity and a healthy diet targeted to improve sarcopenic NAFLD could reduce the risk of significant fibrosis.

Associations between muscle mass, strength, and performance and non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a rising global health issue. The influence of muscle in its pathophysiology has recently gained attention. Our aim was to investigate the association of low muscle mass, strength, and performance with the presence and severity of NAFLD.

METHODS

Patients with metabolic syndrome followed in an outpatient clinic, were consecutively included, between April 1st and December 31st, 2019. Abdominal ultrasound for the diagnosis of NAFLD, NAFLD fibrosis score (NFS) and Fibrosis-4 Index (FIB-4) for determination of significant fibrosis, dual-energy X-ray absorptiometry for calculation of skeletal muscle index (SMI = appendicular skeletal mass / weight x100) and sarcopenic index (SI = appendicular skeletal mass / Body Mass Index), and the Short Physical Performance Battery for muscle strength and performance assessment were performed. Sarcopenia was defined as low muscle strength and low SMI or SI.

RESULTS

A total of 157 patients were included, of which 68.8% had NAFLD, 66.2% low SMI, 50.3% low SI, 16.6% low performance and 11.5% low strength. In patients with NAFLD, prevalence of significant fibrosis by NFS was 15.7%. Low SMI was associated with presence of NAFLD when adjusted for age, sex, type 2 diabetes mellitus, hypertension, and dyslipidemia, but not for body mass index and waist circumference. Low SMI, low SI, and sarcopenia were associated with significant fibrosis in univariate analysis; the small number of events precluded a multivariable analysis.

CONCLUSIONS

Low SMI was associated with NAFLD independently of demographics and comorbidities but not of other parameters of body composition. This contrasts with most studies published on this matter.

Osteosarcopenia in NAFLD/MAFLD: An Underappreciated Clinical Problem in Chronic Liver Disease

Chronic liver disease (CLD), including non-alcoholic fatty liver disease (NAFLD) and its advanced form, non-alcoholic steatohepatitis (NASH), affects a significant portion of the population worldwide. NAFLD is characterised by fat accumulation in the liver, while NASH is associated with inflammation and liver damage. Osteosarcopenia, which combines muscle and bone mass loss, is an emerging clinical problem in chronic liver disease that is often underappreciated. The reductions in muscle and bone mass share several common pathophysiological pathways; insulin resistance and chronic systemic inflammation are the most crucial predisposing factors and are related to the presence and gravity of NAFLD and to the worsening of the outcome of liver disease. This article explores the relationship between osteosarcopenia and NAFLD/MAFLD, focusing on the diagnosis, prevention and treatment of this condition in patients with CLD.

Mediation of 10-Year Cardiovascular Disease Risk between Inflammatory Diet and Handgrip Strength: Base on NHANES 2011-2014

OBJECTIVE

Dietary inflammatory index (DII) and handgrip strength (HGS) were correlated, and both were associated with cardiovascular disease (CVD). However, the role of the 10-year CVD risk in the relationship between DII and grip strength remains uncertain.

METHODS

This study involved 5691 adults from the National Health and Nutrition Examination Survey (NHANES) in 2011-2014. Dietary inflammation, 10-year CVD risk and relative grip strength were assessed by the Dietary Inflammation Index, the Framingham Risk Score (FRS) and handgrip strength adjusted BMI. Linear regression analyses and mediation analysis were used to explore these associations.

RESULTS

Both DII and 10-year CVD risk were negatively associated with relative handgrip strength, and DII was positively associated with 10-year CVD risk. Additionally, 10-year CVD risk partially mediated the association between DII and relative handgrip strength by a 11.8% proportion. Specifically, the mediating effect of the 10-year risk of CVD varied by gender and age.

CONCLUSIONS

Reducing the 10-year risk of CVD attenuates the effect of an inflammatory diet on relative grip strength impairment. Therefore, we recommend reducing the effect of inflammatory diet on grip strength impairment by controlling any of the FRS parameters, such as lowering blood pressure and smoking cessation, especially with targeted measures for different populations.

Different effects of low muscle mass on the risk of non-alcoholic fatty liver disease and hepatic fibrosis in a prospective cohort

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and sarcopenia share insulin resistance as a common pathophysiology and have overlapping clinical manifestation of metabolic derangement; hence, it is difficult to differentiate the independent effect of sarcopenia on the development of NAFLD from concomitant metabolic disorders. Using a community-based prospective cohort study, the contributions of low muscle mass and genetic risk factors to the development of NAFLD and NAFLD-related hepatic fibrosis were investigated in the Korean population.

METHODS

This prospective community-based cohort study included 40-70-year-old adults, followed up biennially from 2001-2002 to 2017-2018. NAFLD was defined as a hepatic steatosis index of ≥36, and hepatic fibrosis was defined based on the fibrosis-4 index. Sex-specific quartiles of body mass index (BMI)-adjusted muscle mass were calculated (muscle mass/BMI), and low muscle mass was defined as the lowest quartile (Q1). Cox proportional hazard models for incident NAFLD or hepatic fibrosis incorporating age, sex, BMI of ≥25 kg/m² , metabolic syndrome and PNPLA3 and TM6SF2 risk alleles were used to assess the independent determinants for incident NAFLD and hepatic fibrosis among individuals with NAFLD at baseline.

RESULTS

Among the 4038 participants without NAFLD at baseline (mean age, 51.5 ± 8.8 years), 920 (22.8%) developed NAFLD during the 12-year follow-up period. As muscle mass decreased, the risk of NAFLD increased even after adjustment for age, sex, obesity, metabolic syndrome and PNPLA3 and TM6SF2 risk alleles [hazard ratio (HR) per quartile, 1.18, 95% confidence interval (CI), 1.11-1.27, P < 0.001]. TM6SF2 also affected the risk of NAFLD development [HR 1.19, (95% CI, 1.00-1.40), P = 0.044]. Of the 1176 patients with NAFLD but without hepatic fibrosis at baseline, the incident of hepatic fibrosis was found in 51.8%, 44.7%, 42.6% and 41.0% in Q1, Q2, Q3 and Q4 of BMI-adjusted muscle mass, respectively, during the follow-up period (P for trend = 0.006). However, this trend lost its statistical significance when adjusted for confounders. The PNPLA3 risk variant, but not the TM6SF2 genotype, was an independent risk factor for developing hepatic fibrosis among patients with NAFLD (HR 1.17, 95% CI 1.04-1.32, P = 0.010).

CONCLUSIONS

Both lower muscle mass index and genetic risk variants are important contributors to the development of NAFLD. In patients already diagnosed with NAFLD, however, PNPLA3 confers a greater risk for hepatic fibrosis progression than lower muscle mass.

Interaction between sarcopenia and nonalcoholic fatty liver disease

Sarcopenia and nonalcoholic fatty liver disease (NAFLD) are common health problems related to aging. Despite the differences in their diagnostic methods, several cross-sectional and longitudinal studies have revealed the close link between sarcopenia and NAFLD. Sarcopenia and NAFLD are linked by several shared pathogenetic mechanisms, including insulin resistance, hormonal imbalance, systemic inflammation, myostatin and adiponectin dysregulation, nutritional deficiencies, and physical inactivity, thus implicating a bidirectional relationship between sarcopenia and NAFLD. However, there is not sufficient data to support a direct causal relationship between sarcopenia and NAFLD. Moreover, it is currently difficult to conclude whether sarcopenia is a risk factor for nonalcoholic steatohepatitis (NASH) or is a consequence of NASH. Therefore, this review intends to touch on the shared common mechanisms and the bidirectional relationship between sarcopenia and NAFLD.

Comparative analysis of the relationship between four hepatic steatosis indices and muscle mass

Several studies have attempted to validate the relationship between hepatic steatosis and sarcopenia. The crucial limitation is to establish the status of hepatic steatosis by costly or invasive methods. Therefore, several models predicting non-alcoholic fatty liver disease (NAFLD) have been developed but have exhibited heterogeneous results. In this study, we aimed to review and compare four representative models and analyze their relationship with the risk of low muscle mass. Korea National Health and Nutrition Examination Surveys from 2008 to 2011 were used to confirm our hypothesis. Dual-energy X-ray absorptiometry was used to measure the amount of skeletal muscle mass. We used four hepatic steatosis indices: hepatic steatosis index (HSI), Framingham steatosis index (FSI), liver fat score (LFS), and fatty liver index (FLI). Multivariate linear and logistic regressions were used to reveal the relationship between NAFLD and low skeletal muscle index (LSMI). Pairs of FSI-FLI and HSI-FLI exhibited the best and second-best correlations among all possible pairs. The four hepatic steatosis models were associated with increased risk for LSMI. After removing the body mass index effect, HSI and FLI remained robust predictors for LSMI. NAFLD was a significant and potent risk factor for low skeletal muscle.

Comparison of the diagnostic value between triglyceride-glucose index and triglyceride to high-density lipoprotein cholesterol ratio in metabolic-associated fatty liver disease patients: a retrospective cross-sectional study

Background

The triglyceride and glucose index (TyG) and triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) are substitute markers of insulin resistance (IR). In a retrospective cross-sectional study, the authors aimed to compare the efficacy of the two indicators in diagnosing metabolic-associated fatty liver disease (MAFLD) to construct a novel disease diagnosis model.

Methods

Overall, 229 patients (97 MAFLD and 132 Non-MAFLD at West China Hospital of Sichuan University were included. MAFLD was diagnosed using ultrasonography. Biochemical indexes were collected and analyzed by logistic regression to screen out indicators that were expressed differently in MAFLD patients and healthy controls, which were incorporated into a diagnostic model.

Results

After adjusting for age, sex, and body mass index (BMI), serum alanine transaminase (ALT), aspartate transaminase (AST), AST/ALT (A/A), fasting plasma glucose (FPG), cystatin C (Cys-C), uric acid (URIC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), non-HDL-C, LDL-C/HDL-C, non-HDL-C/HDL-C, TG/HDL-C, TC/HDL-C, TyG, and TyG-BMI were risk factors for MAFLD. The odds ratio of TG/HDL-C and TyG were 5.629 (95%CI: 3.039–10.424) and 182.474 (95%CI: 33.518–993.407), respectively. In identifying MAFLD, TyG, TyG-BMI, TG, and TG/HDL-C were found to be the most vital indexes based on the random forest method, with the area under the curve (AUC) greater than 0.9. In addition, the combination of BMI, ALT, and TyG had a high diagnostic efficiency for MAFLD.

Conclusions

TyG and TG/HDL-C were potential risk factors for MAFLD, and the former performed better in diagnosing MAFLD. The combination of BMI, ALT, and TyG improved the diagnostic capability for MAFLD.

Impact of non-alcoholic fatty liver disease on the risk of sarcopenia: a nationwide multicenter prospective study

BACKGROUND AND AIMS

Despite the association between sarcopenia and non-alcoholic fatty liver disease (NAFLD), no study has evaluated the predictive role of NAFLD in sarcopenia. We investigated impact of NAFLD on the risk of low muscle mass (LMM) and low muscle strength (LMS) in a nationwide multicenter study.

METHODS

A total of 1595 community-dwelling people aged 70-84 years were followed for 2 years in the Korean Frailty and Aging Cohort Study. Muscle mass was estimated by dividing appendicular skeletal muscle mass (ASM) by body mass index (BMI). Muscle strength was measured as handgrip strength (HGS) divided by BMI. The sex-specific lowest quintiles of ASM/BMI and HGS/BMI of the study population were used as cutoffs for LMM and LMS, respectively. The risk of LMM and LMS were assessed according to hepatic steatosis index (HSI) and fatty liver index (FLI) quartiles.

RESULTS

As HSI quartiles increased, the LMM risk increased gradually, after adjusting for age, sex, lifestyle factors, comorbidities, and several causative factors (insulin resistance, inflammation, and vitamin D) (Q4 vs. Q1 OR [95% CI] 3.46 [2.23-5.35]). The increased risk of LMS was even higher according to HSI quartiles (Q4 vs. Q1 5.81 [3.67-9.21]). Multivariate analyses based on FLI showed similar results. People with NAFLD (HSI > 36) were at higher risk of developing LMM and LMS compared to those without (1.65 [1.19-2.31] and 2.29 [1.61-3.26], respectively).

CONCLUSIONS

The presence of NAFLD may predict future risk of LMM and LMS, with greater impact on LMS than on LMM.

Associations of muscle mass and grip strength with severe NAFLD: A prospective study of 333,295 UK Biobank participants

BACKGROUND & AIMS

Cross-sectional studies have reported that lower muscle mass and strength are risk factors for non-alcoholic fatty liver disease (NAFLD). However, the evidence from prospective studies is limited. This study examined both the strength and pattern of the associations between these 2 physical capability markers and severe NAFLD using data from the UK Biobank study.

METHODS

A total of 333,295 participants were included in this prospective study. Grip strength was measured using a Jamar J00105 hydraulic hand dynamometer, and the Janssen equation was used to estimate skeletal muscle mass by bioelectrical impedance. Muscle mass was adjusted for body weight and all exposures were sex-standardised. Associations of muscle mass and strength with severe NAFLD (defined as hospital admission or death) were first investigated by tertile of each exposure using Cox proportional hazard models. Non-linear associations were investigated using penalised cubic splines fitted in the Cox proportional hazard models.

RESULTS

After a median follow-up of 10 years (IQR 9.3 to 10.7 years), 3,311 individuals had severe NAFLD (3,277 hospitalisations and 34 deaths). Compared with the lowest tertile of muscle mass, the risk of severe NAFLD was lower in the middle (hazard ratio 0.76; 95% CI 0.70-0.83) and the highest tertile (hazard ratio 0.46; 95% CI 0.40-0.52). Tertiles of grip strength showed a similar pattern. Non-linearity was only identified for muscle mass (p <0.001). Being on the lower tertile of grip strength and muscle mass accounted for 17.7% and 33.1% of severe NAFLD cases, respectively.

CONCLUSIONS

Lower muscle mass and grip strength were associated with higher risk of developing severe NAFLD. Interventions to improve physical capability may be protective, but this needs to be investigated in appropriately designed trials.

LAY SUMMARY

Lower muscle mass - both quantity and quality - were associated with a higher risk of severe non-alcoholic fatty liver disease. Therefore, improving muscle mass might be a protective factor against this increasing public health problem.

Assessment of Muscle Quantity, Quality and Function

Sarcopenia is a syndrome characterized by loss of skeletal muscle mass and strength that can increase the risk of physical disability, chronic conditions such as diabetes mellitus and cardiovascular diseases, and long-term mortality. Sarcopenia adversely affects not only the elderly population, but also young adults. This review provides updated definitions of sarcopenia and recommendations for the assessment of muscle quantity and quality.

Association of physical activity with sarcopenia evaluated based on muscle mass and strength in older adults: 2008-2011 and 2014 - 2018 Korea National Health and Nutrition Examination Surveys

Background

Adequate physical activity (PA) is essential for preventing sarcopenia in older adults. However, there are insufficient epidemiological data on the intensity of PA needed to prevent age-related sarcopenia. The purpose of this study was to investigate the association of PA intensity with skeletal muscle mass and muscle strength.

Methods

This was a population-based study with a cross-sectional design that was conducted using data from the 2008 − 2011 and 2014 − 2018 Korea National Health and Nutrition Examination Surveys, which included a total of 11,162 participants aged ≥ 60 years. PA was assessed using the results of a questionnaire and organized by intensity, frequency, and duration. The study population was divided into the following groups based on PA intensity: no exercise, walking only, moderate PA, and vigorous PA. To assess sarcopenia, skeletal muscle index (SMI) and hand grip strength (HGS) were measured as indicators of muscle mass and strength, respectively. Logistic regression analysis was used to explore the relationship between PA intensity and sarcopenia.

Results

SMI and HGS were significantly higher in men and women engaged in moderate to vigorous PA than in those who did not exercise. The odds ratios (ORs) for sarcopenia defined based on SMI and HGS were lowest in men engaged in vigorous PA (0.444, 95% confidence interval [CI]: 0.242 − 0.818 and 0.450, 95% CI: 0.228 − 0.890, respectively). In women, the OR for sarcopenia defined based on HGS was the lowest in the group engaged in vigorous PA (0.441, 95% CI: 0.199 − 0.975), while there was no risk reduction for sarcopenia defined based on SMI.

Conclusions

Moderate to vigorous PA was highly correlated with SMI and HGS in men and women. Intensive PA was positively correlated with sarcopenia prevention, which can be monitored using HGS.

Sex- and region-specific associations of skeletal muscle mass with metabolic dysfunction-associated fatty liver disease

INTRODUCTION

Metabolic dysfunction-associated fatty liver disease (MAFLD) is known to be the most common chronic liver disease worldwide, and accumulating evidence suggests that skeletal muscle might play an important role in metabolic health. However, the association between skeletal muscle and MAFLD is poorly understood so far. Therefore, we aimed to evaluate the associations of skeletal muscle with MAFLD and significant fibrosis.

METHODS

A cross-sectional analysis was conducted using data obtained from the 2017-2018 US National Health and Nutrition Examination Survey. The whole-body, appendicular, and trunk skeletal muscle mass index (SMI) were assessed by dual-energy x-ray absorptiometry. MAFLD and significant fibrosis were assessed by transient elastography. Survey-weight adjusted multivariable logistic regressions were used to determine the associations. The area under the receiver operating characteristic curve (AUC) and variable importance scores from the random forest and logistic regression model were calculated to assess the predictive capability of variables and models.

RESULTS

Of the 2065 participants, those with appendicular SMI in the highest quartile were associated with a lower risk for MAFLD in both sexes (male, OR[95%CI]: 0.46 [0.25~0.84]; female, OR[95%CI]: 0.32 [0.13~0.82]), but with a significantly different scale of the associations between sexes (P _interaction = 0.037). However, females with trunk SMI in the highest quartile had an increased risk of significant fibrosis (OR[95%CI]: 7.82 [1.86~32.77]). Trunk SMI and appendicular SMI ranked the third contributor to MAFLD in random forest and logistic regression models, respectively. Taking appendicular and trunk SMI into consideration, the AUCs for MAFLD were 0.890 and 0.866 in random forest and logistic regression models, respectively.

DISCUSSION

The distribution of skeletal muscle mass differently affects MAFLD and significant fibrosis in the sex groups. Higher appendicular skeletal muscle mass was associated with a lower risk of MAFLD, while the risk of significant fibrosis in females was increased with the trunk skeletal muscle mass.

Clinical characteristics of metabolic associated fatty liver disease (MAFLD) in subjects with myotonic dystrophy type 1 (DM1)

BACKGROUND

Myotonic dystrophy type 1 (DM1) is a rare inherited neuromuscular disease associated with insulin resistance, and its association with metabolically associated fatty liver disease (MAFLD) has never been explored in prospective studies. The aim of this study was to assess the clinical features of MAFLD in DM1 patients.

METHODS

We investigated the prevalence and the diagnostic features of MAFLD in a cohort of 29 outpatient fully characterized DM1 patients; afterward, we compared the selected cohort of DM1-MAFLD individuals with a propensity-matched cohort of non-DM1-MAFLD RESULTS: 13/29 (44.83%) DM1 patients received a clinical diagnosis of MAFLD. Compared to DM1 patients with normal liver, DM1-MAFLD individuals showed a higher male prevalence (p = 0.008), BMI (p = 0.014), HOMA score (p = 0.012), and GGT levels (p = 0.050). The statistical comparison showed that the DM1-MAFLD group had a more severe MAFLD according to the FIB4 score than non-DM1-MAFLD patients. This association of a more severe form of liver disease with DM1 remained significant after logistic regression analysis (OR: 6.12, 95% CI 1.44- 26.55).

Non-alcoholic fatty liver disease and sarcopenia additively increase mortality: a Korean nationwide survey

BACKGROUND

Sarcopenia is an independent risk factor not only for advanced-stage non-alcoholic fatty liver disease (NAFLD) but also for mortality. We investigated the association of sarcopenia and/or NAFLD with mortality among the Korean general population.

METHODS

Individuals aged 35-75 years without any history of cancer, ischaemic heart disease, ischaemic stroke, or secondary causes of chronic liver disease were selected from the Korean National Health and Nutrition Examination Surveys from 2008 to 2015. Their mortality data until December 2018 were retrieved from the National Death Registry. NAFLD and sarcopenia were defined by hepatic steatosis index and appendicular skeletal muscle mass divided by body mass index (BMI), respectively.

RESULTS

A total of 28 060 subjects were analysed [mean age, 50.6 (standard error, 0.1) years, 48.2 (0.3) % men]; the median follow-up duration was of 6.8 (interquartile range, 4.8, 8.4) years. NAFLD predicted mortality after adjustment for age, sex, BMI, hypertension, dyslipidaemia, and smoking (HR 1.32, 95% CI 1.03-1.70), but this prediction lost its statistical significance after additional adjustment for diabetes mellitus. In contrast, NAFLD with advanced fibrosis independently increased the risk of mortality after adjustment for all covariates (HR 1.68, 95% CI 1.02-2.79). Stratified analysis revealed that NAFLD and sarcopenia additively increased the risk of mortality as an ordinal scale (HR 1.46, 95% CI 1.18-1.81, P for trend = 0.001). The coexistence of NAFLD and sarcopenia increased the risk of mortality by almost twice as much, even after adjustment for advanced fibrosis (HR 2.18, 95% CI 1.38-3.44).

CONCLUSIONS

Concurrent NAFLD and sarcopenia conferred a two-fold higher risk of mortality. The observation that NAFLD and sarcopenia additively increase mortality suggests that risk stratification would be helpful in predicting mortality among those with metabolic derangement.

Association Between Muscle Strength and Cystatin C-Based Estimated Glomerular Filtration Rate Among Middle-Aged and Elderly Population: Findings Based on the China Health and Retirement Longitudinal Study (CHARLS), 2015

Background

Patients with chronic kidney disease (CKD) are prone to muscle strength degeneration. However, the relationship between mild-to-moderate renal insufficiency and low muscle strength remains unclear. As cystatin C is not subject to muscular conditions and is a sensitive serum marker in preclinical renal disease, we aimed to investigate the association between estimated glomerular filtration rate (eGFR) based on cystatin C and muscle strength in the Chinese population.

Methods

This was a cross-sectional study enrolling 12,398 Chinese participants aged above 45 years (5762 men and 6636 women) from the 2015 China Health and Retirement Longitudinal Study. Handgrip strength (HGS) was used to assess muscle strength. Locally weighted scatterplot smoothing (LOWESS) curves were employed to visualize the relationships between eGFR and HGS. Multivariable logistic regression was conducted to analyze the correlation between kidney function and low muscle strength.

Results

Significant differences in HGS by CKD stage were observed in both sexes after adjusting for age and body mass index. LOWESS curves demonstrated concomitant decreases in HGS and kidney function at eGFR levels below 120 mL/min/1.73 m² in both sexes. According to multivariate logistic regression, participants with CKD stages 2 (odds ratio [OR]: 1.256, 95% confidence interval [CI]: 1.120–1.409), 3 (OR: 2.725, 95% CI: 2.2585–3.288), and 4–5 (OR: 3.069, 95% CI 1.747–5.392) had higher risk of low muscle strength than those who were normal or had CKD stage 1 after adjusting for demographic and clinical variables.

Conclusion

Our study illustrated that CKD stage was independently associated with low muscle strength in Chinese middle-aged and elderly populations.

Myosteatosis rather than sarcopenia associates with non-alcoholic steatohepatitis in non-alcoholic fatty liver disease preclinical models

BACKGROUND

Non-alcoholic fatty liver (NAFL) disease (NAFLD) is the most common chronic liver disease in the world. While most subjects have 'inert' NAFL, a subset will progress to non-alcoholic steatohepatitis (NASH) and its life-threatening complications. A substantial body of literature supports that a low muscle mass, low strength, and/or muscle fatty infiltration (myosteatosis) are associated with NAFLD severity. Here, we evaluated the muscle compartment in NASH preclinical models to decipher the kinetics of muscle alterations in relation with liver disease progression.

METHODS

We developed and validated a micro-computed tomography-based methodology to prospectively study skeletal muscle mass and density in muscle and liver (i.e. reflecting fatty infiltration) in a high-throughput and non-invasive manner in three preclinical NAFLD/NASH rodent models: fat aussie (FOZ) mice fed a high-fat diet (FOZ HF), wild-type (WT) mice fed a high-fat high-fructose diet (WT HFF), and WT mice fed a high-fat diet (WT HF). We compared them with WT mice fed a normal diet (WT ND) used as controls.

RESULTS

-FOZ HF with fibrosing NASH had sarcopenia characterized by a reduced muscle strength when compared with WT HF and WT HFF with early NASH and WT ND controls (165.2 ± 5.2 g vs. 237.4 ± 11.7 g, 256 ± 5.7 g, and 242.9 ± 9.3 g, respectively, P 60; 0.001). Muscle mass or strength was not lower in FOZ HF, WT HF, and WT HFF with early NASH than in controls. Myosteatosis was present in FOZ HF with fibrosing NASH, but also in FOZ HF, WT HF, and WT HFF with early NASH (muscle density = 0.50 ± 0.02, 0.62 ± 0.02, 0.70 ± 0.05, and 0.75 ± 0.03, respectively, with P 60; 0.001 when compared with respective controls). Myosteatosis degree was strongly correlated with NAFLD activity score (r = -0.87, n = 67, P 60; 0.001). In multivariate analysis, the association between myosteatosis and NASH was independent from homeostatic model assessment of insulin resistance and visceral fat area (P 60; 0.05). Myosteatosis degree powerfully discriminated NASH from benign NAFL and normal liver (area under the receiver operating characteristic = 0.96, n = 67, P 60; 0.001).

CONCLUSIONS

Taken together, our data support that there is no sarcopenia in obese mice with early NASH. In contrast, the severity of myosteatosis reflects on hepatocellular damage and inflammation during early NASH development. This observation prompts us to exploit myosteatosis as a novel non-invasive marker of NASH.

Nonalcoholic fatty liver disease and sarcopenia: pathophysiological connections and therapeutic implications

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is currently one of the most common liver diseases worldwide. Recent data suggest that loss of skeletal muscle mass and function (i.e. sarcopenia) is highly prevalent and frequently overlooked in NAFLD patients. Experimental and clinical data suggest that the relationship between NAFLD and sarcopenia is pathophysiologically complex and bi-directional and there is a growing interest in unveiling how sarcopenia could influence NAFLD development and progression.

AREAS COVERED

PubMed/MEDLINE was searched for articles related to concomitant occurrence of NAFLD and sarcopenia between January 2013 and April 2020. Areas covered in this review include: (1) updated sarcopenia diagnosis strategy, (2) discussion of current data on pathophysiological connections between NAFLD and sarcopenia, and (3) analysis of current and future therapeutic implications of this knowledge.

EXPERT OPINION

Clinical studies describe a consistent association between NAFLD and sarcopenia, although a cause-effect relation remains to be determined. Active implementation of current diagnosis algorithms and optimized treatment can prevent sarcopenia related complications in subjects with NAFLD. Pathogenic pathways implicated in this relation are multiple and complex, a better understanding of them can provide novel biomarkers and targeted therapies that will hopefully have an important impact in NAFLD management.

Association between muscle strength and advanced fibrosis in non-alcoholic fatty liver disease: a Korean nationwide survey

BACKGROUND

We investigated the association between muscle strength and the prevalence of advanced fibrosis among individuals with non-alcoholic fatty liver disease (NAFLD) using a nationwide cross-sectional survey.

METHODS

Individuals, 20 to 79 years of age, from the Korean National Health and Nutrition Examination Surveys (KNHANES) from 2014 to 2016 were selected (N = 14 861), with sample weights applied. Muscle strength was quantified as the handgrip strength divided by the body mass index (BMI); low muscle strength (LMS) was defined as the lowest quartile (Q1 ) of the handgrip strength/BMI for our sample population. NAFLD was defined as hepatic steatosis index >36. Advanced fibrosis was defined as a fibrosis-4 index score ≥1.30 (FibrosisFIB4 ).

RESULTS

The mean age of the study population was 45.6 ± 0.2 years, and 42.4% were male. As muscle strength increased, the mean BMI and age decreased accordingly, and the proportions of diabetes, dyslipidaemia, hypertension, and obesity decreased significantly (P < 0.001 for all). In a crude analysis, the LMS was associated with an increased prevalence of NAFLD (odds ratio [OR] 3.62, 95% confidence interval [CI] 3.25-4.03, P < 0.001), which remained significant even after adjustment for age, sex, obesity, insulin resistance, diabetes, hypertension, dyslipidaemia, and high-sensitivity C-reactive protein (OR 1.66, 95% CI 1.28-2.16, P < 0.001). In this logistic regression model, the prevalence of NAFLD decreased by 24% with each quartile increment in muscle strength (OR 0.76, 95% CI 0.68-0.85, P < 0.001). Among individuals with NAFLD (n = 2092), LMS was significantly associated with the presence of advanced fibrosis (FibrosisFIB4 ) independently of age, sex, obesity, diabetes, hypertension, dyslipidaemia, and high-sensitivity C-reactive protein (OR 1.66, 95% CI 1.01-2.49, P = 0.015), which lost its statistical significance after additional adjustment for insulin resistance.

CONCLUSIONS

Low muscle strength is independently associated with NAFLD. The significant association between LMS and advanced fibrosis in NAFLD may be mediated through insulin resistance.