The Association between Nonalcoholic Fatty Liver Disease and CT-Measured Skeletal Muscle Mass

Association between non-alcoholic fatty liver disease and risk of sarcopenia: a systematic review and meta-analysis

OBJECTIVES

To determine the association of non-alcoholic fatty liver disease (NAFLD) with the incidence of sarcopenia.

DESIGN

Systematic review and meta-analysis of observational clinical studies.

SETTING AND PARTICIPANTS

Adults with NAFLD.

METHODS

Databases such as PubMed, Embase, Cochrane and Web of Science were searched for eligible studies published from the inception of each database up to 4 April 2023. All cross-sectional studies on the association between NAFLD and sarcopenia were included in this study. The quality of the included studies and risk of bias was assessed using the Agency for Healthcare Research and Quality checklist. STATA V.15.1 software was used for statistical analysis.

RESULTS

Of the 1524 retrieved articles, 24 were included in this review, involving 88 609 participants. Our findings showed that the prevalence of sarcopenia was higher in the NAFLD group than in the control group (pooled OR 1.74, 95% CI 1.39 to 2.17). In a subgroup analysis by region, patients with NAFLD showed an increased risk of sarcopenia (pooled OR 1.97, 95% CI 1.54 to 2.51) in the Asian group, whereas patients with NAFLD had no statistically significant association with the risk of sarcopenia in the American and European groups, with a pooled OR of 1.31 (95% CI 0.71 to 2.40) for the American group and a pooled OR of 0.99 (95% CI 0.21 to 4.69) for the European group. Similar results were observed in the sensitivity analysis, and no evidence of publication bias was observed.

CONCLUSIONS AND IMPLICATIONS

The current study indicated a significant positive correlation between NAFLD and sarcopenia, which may be affected by regional factors. This study provides the correlation basis for the relationship between NAFLD and sarcopenia and helps to find the quality strategy of sarcopenia targeting NAFLD.

Association of Uric Acid to Creatinine Ratio with Metabolic Dysfunction-Associated Fatty Liver in Non-Obese Individuals Without Type 2 Diabetes Mellitus

Introduction

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common chronic liver disease, which is usually associated with type 2 diabetes mellitus (T2DM) and obesity. However, the incidence of MALFD in non-obese individuals without T2DM is increasing, and the pathogenesis is unclear. Serum uric acid to creatinine ratio (sUA/Cr) can reflect overall metabolic status. This study aims to observe the association between sUA/Cr and MAFLD in non-obese individuals without T2DM.

Methods

A total of 21,996 individuals were included in this study. The subjects were divided into four subgroups: non-obese patients without T2DM, obese patients without T2DM, non-obese patients with T2DM, and obese patients with T2DM. Logistic regression analyzed the correlation between sUA/Cr and MAFLD subgroups. Receiver operating characteristics analyzed the predictive value of sUA/Cr for MAFLD subgroups. The stratified analyses by sex and age were performed.

Results

Non-obese MAFLD individuals without T2DM had higher sUA/Cr levels than their counterparts. sUA/Cr was significantly correlated positively with MAFLD in non-obese patients. Similar results were observed in both males and females and in populations at all age stages (all p<0.01). sUA/Cr was capable of discriminating MAFLD in non-obese individuals without T2DM (AUC: 0.667), especially for patients over 60 years old (AUC: 0.704).

Conclusion

The sUA/Cr ratio was correlated with MAFLD in non-obese patients without T2DM. The predictive value of sUA/Cr for MAFLD was observed. Hence, the sUA/Cr ratio might be given more concern for the risk of MAFLD in non-obese individuals without T2DM.

Association of Visceral Fat Obesity, Sarcopenia, and Myosteatosis with Non-Alcoholic Fatty Liver Disease without Obesity

BACKGROUND/AIMS

To investigate whether non-alcoholic fatty liver disease (NAFLD) in individuals without generalized obesity is associated with visceral fat obesity (VFO), sarcopenia, and/or myosteatosis.

METHODS

This cross-sectional analysis included 14,400 individuals (7,470 men) who underwent abdominal computed tomography scans during routine health examinations. The total abdominal muscle area (TAMA) and skeletal muscle area (SMA) at the 3rd lumbar vertebral level were measured. The SMA was divided into the normal attenuation muscle area (NAMA) and low attenuation muscle area, and the NAMA/TAMA index was calculated. VFO was defined by visceral to subcutaneous fat ratio, sarcopenia by body mass index-adjusted SMA, and myosteatosis by the NAMA/TAMA index. NAFLD was diagnosed with ultrasonography.

RESULTS

Of the 14,400 individuals, 4,748 (33.0%) had NAFLD, and the prevalence of NAFLD among non-obese individuals was 21.4%. In regression analysis, both sarcopenia (men: odds ratio [OR] 1.41, 95% confidence interval [CI] 1.19-1.67, P<0.001; women: OR=1.59, 95% CI 1.40-1.90, P<0.001) and myosteatosis (men: OR=1.24, 95% CI 1.02-1.50, P=0,028; women: OR=1.23, 95% CI 1.04-1.46, P=0.017) were significantly associated with non-obese NAFLD after considering for VFO and other various risk factors, whereas VFO (men: OR=3.97, 95% CI 3.43-4.59 [adjusted for sarcopenia], OR 3.98, 95% CI 3.44-4.60 [adjusted for myosteatosis]; women: OR=5.42, 95% CI 4.53-6.42 [adjusted for sarcopenia], OR=5.33, 95% CI 4.51-6.31 [adjusted for myosteatosis]; all P<0.001) was strongly associated with non-obese NAFLD after adjustment with various known risk factors.

CONCLUSION

In addition to VFO, sarcopenia and/or myosteatosis were significantly associated with non-obese NAFLD.

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.

Association between Regional Body Muscle Mass and Non-Alcoholic Fatty Liver Disease: An Observational Study Using Data from the REACTION Study

Background and aims: Regional muscle distribution is associated with abdominal obesity and metabolic syndrome. However, the relationship between muscle distribution and nonalcoholic fatty liver disease (NAFLD) remains unclear. This study was to determine the relationship between regional muscle distribution and the risk and severity of NAFLD. Methods: This cross-sectional study ultimately included 3161 participants. NAFLD diagnosed by ultrasonography was classified into three groups (non, mild, and moderate/severe). We estimated the regional body muscle mass (lower limbs, upper limbs, extremities, and trunk) through multifrequency bioelectrical impedance analysis (BIA). The relative muscle mass was defined as the muscle mass adjusted for the body mass index (BMI). Results: NAFLD participants accounted for 29.9% (945) of the study's population. Individuals with a higher lower limb, extremity, and trunk muscle mass had a lower risk of NAFLD (p < 0.001). Patients with moderate/severe NAFLD had a lower muscle mass of the lower limbs and trunk than patients with mild NAFLD (p < 0.001), while the muscle mass of the upper limbs and extremities did not differ significantly between the two groups. Moreover, similar results were found for both sexes and among different age groups. Conclusions: A higher muscle mass of the lower limbs, extremities, and trunk was negatively associated with the risk of NAFLD. A lower muscle mass of the limbs and trunk was inversely associated with the severity of NAFLD. This study provides a new theoretical basis for the development of individualized exercise prescriptions for the prevention of NAFLD in non-NAFLD patients.

Prevalence of Low Muscle Mass in the Computed Tomography at the Third Lumbar Vertebra Level Depends on Chosen Cut-Off in 200 Hospitalised Patients-A Prospective Observational Trial

Measuring skeletal muscle area (SMA) at the third lumbar vertebra level (L3) using computed tomography (CT) is increasingly popular for diagnosing low muscle mass. The aim was to describe the effect of the CT L3 cut-off choice on the prevalence of low muscle mass in medical and surgical patients. Two hundred inpatients, who underwent an abdominal CT scan for any reason, were included. Skeletal muscle area (SMA) was measured according to Hounsfield units on a single CT scan at the L3 level. First, we calculated sex-specific cut-offs, adjusted for height or BMI and set at mean or mean-2 SD in our population. Second, we applied published cut-offs, which differed in statistical calculation and adjustment for body stature and age. Statistical calculation of the cut-off led to a prevalence of approximately 50 vs. 1% when cut-offs were set at mean vs. mean-2 SD in our population. Prevalence varied between 5 and 86% when published cut-offs were applied (p < 0.001). The adjustment of the cut-off for the same body stature variable led to similar prevalence distribution patterns across age and BMI classes. The cut-off choice highly influenced prevalence of low muscle mass and prevalence distribution across age and BMI classes.

Standardized measurement of abdominal muscle by computed tomography: association with cardiometabolic risk in the Framingham Heart Study

Objectives

To provide a standard for total abdominal muscle mass (TAM) quantification on computed tomography (CT) and investigate its association with cardiovascular risk in a primary prevention setting.

Methods

We included 3016 Framingham Heart Study participants free of cardiovascular disease (CVD) who underwent abdominal CT between 2002 and 2005. On a single CT slice at the level of L3/L4, we segmented (1) TAM-Area, (2) TAM-Index (= TAM-Area/height) and, (3) TAM-Fraction (= TAM-Area/total cross-sectional CT-area). We tested the association of these muscle mass measures with prevalent and incident cardiometabolic risk factors and incident CVD events during a follow-up of 11.0 ± 2.7 years.

Results

In this community-based sample (49% women, mean age: 50.0 ± 10.0 years), all muscle quantity measures were significantly associated with prevalent and incident cardiometabolic risk factors and CVD events. However, only TAM-Fraction remained significantly associated with key outcomes (e.g., adj. OR 0.68 [0.55, 0.84] and HR 0.73 [0.57, 0.92] for incident hypertension and CVD events, respectively) after adjustment for age, sex, body mass index, and waist circumference. Moreover, only higher TAM-Fraction was associated with a lower risk (e.g., adj. OR: 0.56 [0.36–0.89] for incident diabetes versus TAM-Area: adj. OR 1.26 [0.79–2.01] and TAM-Index: 1.09 [0.75–1.58]).

Conclusion

TAM-Fraction on a single CT slice at L3/L4 is a novel body composition marker of cardiometabolic risk in a primary prevention setting that has the potential to improve risk stratification beyond traditional measures of obesity.

Key Points

• In this analysis of the Framingham Heart Study (n = 3016), TAM-F on a single slice CT was more closely associated with prevalent and incident cardiometabolic risk factors as compared to TAM alone or TAM indexed to body surface area.

• TAM-F on a single abdominal CT slice at the level of L3/L4 could serve as a standard measure of muscle mass and improve risk prediction

"Bioelectrical impedance analysis in managing sarcopenic obesity in NAFLD"

INTRODUCTION

Sarcopenic obesity and its association with nonalcoholic fatty liver disease (NAFLD) is under-recognized by many healthcare providers in Western medicine due to the lack of awareness and diagnostic guidelines. The result is delayed recognition and treatment, which leads to further health deterioration and increased healthcare costs. Sarcopenic obesity is characterized by the presence of increased fat mass in combination with muscle catabolism related to chronic inflammation and/or inactivity. Previous research has recommended evaluating body composition and physical function performance to adequately diagnose sarcopenic obesity. Body composition analysis can be performed by imaging applications through magnetic resonance imaging, computed tomography, and dual-energy x-ray absorptiometry. Due to the cost of each device and radiation exposure for patients as evidenced in all three modalities, bioelectrical impedance analysis offers a noninvasive approach capable of providing quick and reliable estimates of lean body and fat mass.

METHODS AND RESULTS

This review analyzes the current evidence-based literature, indicating a lower skeletal muscle mass and increased visceral adipose tissue correlation to the advancement of fibrosis in fatty liver disease.

CONCLUSION

Given the substantial promising research conducted in predominantly Asian populations regarding body tissue distribution and NAFLD, additional prospective research is needed to extend these findings in Western populations.

A dynamic association between myosteatosis and liver stiffness: Results from a prospective interventional study in obese patients

Background & Aims

Retrospective cross-sectional studies linked sarcopenia and myosteatosis with metabolic dysfunction-associated fatty liver disease (MAFLD). Here, we wanted to clarify the dynamic relationship between sarcopenia, myosteatosis, and MAFLD.

Methods

A cohort of 48 obese patients was randomised for a dietary intervention consisting of 16 g/day of inulin (prebiotic) or maltodextrin (placebo) supplementation. Before and after the intervention, we evaluated liver steatosis and stiffness with transient elastography (TE); we assessed skeletal muscle index (SMI) and skeletal muscle fat index (SMFI) (a surrogate for absolute fat content in muscle) using computed tomography (CT) and bioelectrical impedance analysis (BIA).

Results

At baseline, sarcopenia was uncommon in patients with MAFLD (4/48, 8.3%). SMFI was higher in patients with high liver stiffness than in those with low liver stiffness (640.6 ± 114.3 cm²/ Hounsfield unit [HU] vs. 507.9 ± 103.0 cm²/HU, p = 0.001). In multivariate analysis, SMFI was robustly associated with liver stiffness even when adjusted for multiple confounders (binary logistic regression, p <0.05). After intervention, patients with inulin supplementation lost weight, but this was not associated with a decrease in liver stiffness. Remarkably, upon intervention (being inulin or maltodextrin), patients who lowered their SMFI, but not those who increased SMI, had a 12.7% decrease in liver stiffness (before = 6.36 ± 2.15 vs. after = 5.55 ± 1.97 kPa, p = 0.04).

Conclusions

Myosteatosis, but not sarcopenia, is strongly and independently associated with liver stiffness in obese patients with MAFLD. After intervention, patients in which the degree of myosteatosis decreased reduced their liver stiffness, irrespective of body weight loss or prebiotic treatment. The potential contribution of myosteatosis to liver disease progression should be investigated.

Clinical Trials registration number

NCT03852069.

Lay summary

The fat content in skeletal muscles (or myosteatosis) is strongly associated with liver stiffness in obese patients with MAFLD. After a dietary intervention, patients in which the degree of myosteatosis decreased also reduced their liver stiffness. The potential contribution of myosteatosis to liver disease progression should be investigated.

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Low-radiation CT scan enables muscle evaluation (quantity and composition).

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Muscle mass is not low in patients with MAFLD and high liver stiffness.

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In contrast, myosteatosis is strongly associated with liver stiffness.

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Lower myosteatosis after dietary intervention is associated with improved MAFLD.

Nonalcoholic Steatohepatitis, Sarcopenia, and Liver Transplantation

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Radiologic Definition of Sarcopenia in Chronic Liver Disease

Sarcopenia is prevalent in patients with chronic liver disease, and affected patients tend to have worse clinical outcomes and higher mortality. However, relevant analyses are limited by heterogeneity in the definition of sarcopenia and in the methodological approaches in assessing it. We reviewed several radiologic methods for sarcopenia in patients with chronic liver disease. Dual energy X-ray absorptiometry (DXA) can measure muscle mass, but it is difficult to evaluate muscle quality using this technique. Computed tomography, known as the gold standard for diagnosing sarcopenia, enables the objective measurement of muscle quantity and quality. The third lumbar skeletal muscle index (L3 SMI) more accurately predicted the mortality of subjects than the psoas muscle index (PMI). Few studies have evaluated the sarcopenia of chronic liver disease using ultrasonography and magnetic resonance imaging, and more studies are needed. Unification of the measurement method and cut-off value would facilitate a more systematic and universal prognosis evaluation in patients with chronic liver disease.

Radiologic Definition of Sarcopenia in Chronic Liver Disease

Sarcopenia is prevalent in patients with chronic liver disease, and affected patients tend to have worse clinical outcomes and higher mortality. However, relevant analyses are limited by heterogeneity in the definition of sarcopenia and in the methodological approaches in assessing it. We reviewed several radiologic methods for sarcopenia in patients with chronic liver disease. Dual energy X-ray absorptiometry (DXA) can measure muscle mass, but it is difficult to evaluate muscle quality using this technique. Computed tomography, known as the gold standard for diagnosing sarcopenia, enables the objective measurement of muscle quantity and quality. The third lumbar skeletal muscle index (L3 SMI) more accurately predicted the mortality of subjects than the psoas muscle index (PMI). Few studies have evaluated the sarcopenia of chronic liver disease using ultrasonography and magnetic resonance imaging, and more studies are needed. Unification of the measurement method and cut-off value would facilitate a more systematic and universal prognosis evaluation in patients with chronic liver disease.

Harnessing Muscle-Liver Crosstalk to Treat Nonalcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) has reached epidemic proportions, affecting an estimated one-quarter of the world's adult population. Multiple organ systems have been implicated in the pathophysiology of NAFLD; however, the role of skeletal muscle has until recently been largely overlooked. A growing body of evidence places skeletal muscle-via its impact on insulin resistance and systemic inflammation-and the muscle-liver axis at the center of the NAFLD pathogenic cascade. Population-based studies suggest that sarcopenia is an effect-modifier across the NAFLD spectrum in that it is tightly linked to an increased risk of non-alcoholic fatty liver, non-alcoholic steatohepatitis (NASH), and advanced liver fibrosis, all independent of obesity and insulin resistance. Longitudinal studies suggest that increases in skeletal muscle mass over time may both reduce the incidence of NAFLD and improve preexisting NAFLD. Adverse muscle composition, comprising both low muscle volume and high muscle fat infiltration (myosteatosis), is highly prevalent in patients with NAFLD. The risk of functional disability conferred by low muscle volume in NAFLD is further exacerbated by the presence of myosteatosis, which is twice as common in NAFLD as in other chronic liver diseases. Crosstalk between muscle and liver is influenced by several factors, including obesity, physical inactivity, ectopic fat deposition, oxidative stress, and proinflammatory mediators. In this perspective review, we discuss key pathophysiological processes driving sarcopenia in NAFLD: anabolic resistance, insulin resistance, metabolic inflexibility and systemic inflammation. Interventions that modify muscle quantity (mass), muscle quality (fat), and physical function by simultaneously engaging multiple targets and pathways implicated in muscle-liver crosstalk may be required to address the multifactorial pathogenesis of NAFLD/NASH and provide effective and durable therapies.

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.

Relative Skeletal Muscle Mass Is an Important Factor in Non-Alcoholic Fatty Liver Disease in Non-Obese Children and Adolescents

Recently, sarcopenia was identified as a risk factor for non-alcoholic fatty liver disease (NAFLD) in adults. We here investigated the association between skeletal muscle mass (SMM) and NAFLD in non-obese children and adolescents. A retrospective medical chart review was performed for individuals aged 9–15 years diagnosed with NAFLD. Healthy volunteers aged 9–15 years were recruited as controls. Participants were subject to laboratory tests, abdominal sonography, and multi-frequency bioelectrical impedance analysis. SMM data were calculated as the skeletal muscle-to-body fat ratio (MFR), and the diagnosis of fatty liver was established by abdominal sonography. The control and NAFLD groups included 73 and 53 individuals, respectively. No significant difference was observed in gender and body mass index (BMI) distribution between the groups. Mean MFR was significantly lower in individuals with NAFLD than in those without (0.83 vs. 1.04, p = 0.005). After adjusting for age, sex, BMI, and serum glucose, the risk of having NAFLD was significantly associated with a decreased MFR (p = 0.016). NAFLD is significantly associated with relatively low SMM in non-obese children and adolescents. Increasing SMM, such as weight training, can be suggested as one of the treatment strategies in pediatric NAFLD without obesity.

Muscle Mass Is Linked to Liver Disease Severity in Pediatric Nonalcoholic Fatty Liver Disease

OBJECTIVE

To investigate the association between muscle mass and liver disease severity in pediatric patients with non-alcoholic fatty liver disease (NAFLD).

STUDY DESIGN

This was a retrospective study of patients aged <20 years followed from 2009 to 2018. Muscle mass was estimated in all patients by measuring magnetic resonance imaging-based total psoas muscle surface area (tPMSA) and correcting for height (tPMSA index = tPMSA/height²). Two cohorts were studied, one with histological confirmation of NAFLD (n = 100) and the other with magnetic resonance imaging (MRI) evidence of hepatic steatosis (n = 236). Histology was scored using Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) criteria. MRI-measured proton density fat fraction (PDFF) and liver stiffness were collected. Demographic, clinical, and socioeconomic status (using a validated Community Deprivation Index [CDI]) were assessed as covariates. Univariate regression analyses, followed by multivariable regression analyses, were used to determine the relationships between tPMSA index and NAS, MRI-PDFF, and liver stiffness, adjusting for clinical, demographic, and CDI variables.

RESULTS

In the multivariable regression analyses, higher steatosis score was associated with a lower tPMSA index (OR, 0.73; 95% CI, 0.56-0.96) and younger age (OR, 0.84; 95% CI, 0.73-0.97). Liver PDFF was also significantly associated with the tPMSA index (P = .029), sex (P = .019), and CDI (P = .005). In contrast, liver stiffness was not associated with tPMSA in multivariable analyses.

CONCLUSIONS

tPMSA index was independently associated with both imaging and histological features of hepatic steatosis severity in children. Future studies should directly explore the presence and directionality of causative links between muscle mass and steatosis, as well as whether interventions that enhance muscle mass can reduce disease severity in children with NAFLD.

Trunk muscle quality and quantity predict the development of metabolic syndrome and the increase in the number of its components in individuals without metabolic syndrome

BACKGROUND AND AIMS

The metabolic syndrome has been reported by cross-sectional studies to have an association with skeletal muscle quality and quantity. Using a longitudinal study design, this study aimed to explicate the association between muscle characteristics assessed with computed tomography (CT) and the incidence and progression of metabolic syndrome.

METHODS AND RESULTS

In this retrospective study on a cohort of employees undergoing annual physical examinations, we evaluated data from 554 participants without metabolic syndrome. The cross-sectional skeletal muscle area was determined based on CT data at the level of the third lumbar vertebra, and the skeletal muscle density (SMD) and skeletal muscle index (SMI) were measured. The participants were divided into four study groups according to the sex-specific median values for SMI and SMD. We followed the participants for a mean period of 3.1 years. In the sex- and age-adjusted model, SMI and SMD had an interaction effect on the longitudinal change in number of metabolic syndrome components (β = -0.074, p = 0.0727). Multiple regression analyses revealed that both low SMI and SMD was significantly associated with the change (β = 0.131, p = 0.0281), whereas the low SMI and high SMD, and high SMI and low SMD were not. Both low SMI and SMD (hazard ratio (HR), 2.42; 95% confidence interval, 1.28-4.78) showed an increased adjusted HR for incident metabolic syndrome.

CONCLUSION

The participants with both low quality and quantity of skeletal muscles were associated with the incidence and progression of metabolic syndrome, whereas those with only low quantity or quality of skeletal muscles were not.

Relationship between relative skeletal muscle mass and nonalcoholic fatty liver disease: a systematic review and meta-analysis

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) has gradually become one of the most common chronic liver diseases in the world. More and more evidence shows that low skeletal muscle mass index (SMI) may play a role in the development of NAFLD. Our aim was to quantify the association between SMI, sarcopenia and the presence and severity of NAFLD.

METHODS

We systematically searched English relevant studies from PubMed, Embase, the Web of Science and the Cochrane Library updated to December 20th, 2018. Studies in which SMI was compared between NAFLD cases and controls were included. So were studies concerning the odds ratio (OR) of NAFLD, non-alcoholic steatohepatitis (NASH) and significant fibrosis in sarcopenia patients. Pooled weighted mean differences and ORs were calculated.

RESULTS

Of the 1331 retrieved studies, 19 articles were included. SMI level in NAFLD patients was 1.77 (95% CI 1.15, 2.39) lower than that in normal controls. We also found a significantly higher occurrence risk of NAFLD (OR = 1.33, 95% CI 1.20 to 1.48), NASH (OR = 2.42, 95% CI 1.27 to 3.57) and NAFLD-related significant fibrosis (OR = 1.56, 95% CI 1.34, 1.78) in sarcopenia subjects.

CONCLUSIONS

SMI level in patients with NAFLD was lower than healthy people, and patients with sarcopenia have higher occurrence risk of NAFLD, as well as its advanced stages including NASH or NAFLD-related significant fibrosis. Further well-designed prospective studies are required to strengthen the arguments.

Relationship between nonalcoholic fatty liver disease and muscle quality as well as quantity evaluated by computed tomography

BACKGROUND & AIMS

Sarcopenia is reported to be associated with nonalcoholic fatty liver disease (NAFLD). Evaluation of skeletal muscle attenuation and area by computed tomography (CT) may represent a promising approach for evaluation of the risk of NAFLD. We examined the association between skeletal muscle characteristics and NAFLD and investigated the combined effect of these parameters on the prevalence of NAFLD.

METHODS

In this cross-sectional study, we analysed data from 632 middle-aged Japanese subjects without daily alcohol intake (353 men and 279 women) from a cohort of employees undergoing annual health examinations. The cross-sectional skeletal muscle area was evaluated on the basis of CT data at the level of the third lumbar vertebrae, and the skeletal muscle index (SMI) and density (SMD) were calculated. The subjects were divided into four study groups according to their SMI and SMD relative to median values.

RESULTS

One hundred forty men and forty-three women had NAFLD. Total SMI (odds ratio [OR] per 1.0 cm² /kg/m² increase 0.43, 95% confidence interval [CI] 0.29-0.64 in men and OR 0.21, 95% CI 0.10-0.42 in women) and total SMD (OR, per 1.0 Hounsfield Unit increase 0.88, 95% CI 0.83-0.93 in men and 0.88, 0.82-0.95 in women) were significantly associated with the prevalence of NAFLD after adjusting for covariates. The subgroup with simultaneous presence of low SMI and low SMD was associated with a significantly higher prevalence of NAFLD compared with other groups.

CONCLUSIONS

Both SMI and SMD are independently associated with the prevalence of NAFLD.

[Epidemiology of non-alcoholic steatohepatitis. Extent/burden of the problem and its impact on public health]

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of liver disease, the most common cause of chronic liver function augmentation and it will be the most common indication for liver transplantation in 2020. The prevalence of NAFLD has increased over time in line with the increase of obesity and type 2 diabetes. There is a discrepancy between the studies concerning the prevalence of NAFLD because of the different diagnostic methods used (ultrasound or magnetic resonance, fibroscan, controlled attenuation parameter (CAP), histology). Because of its high prevalence the impact of NAFLD in public health is real. Therapeutic advances must be made to better understand the natural history of NAFLD and improve the management of this emerging liver disease.

Sarcopenia in Older Adults

Sarcopenia was first described in 1988 as the age-related decline of skeletal muscle mass [...].

Association between CT-Measured Abdominal Skeletal Muscle Mass and Pulmonary Function

A relationship between lung function and sarcopenia has been suggested. This study aimed to evaluate the association between lung function and abdominal skeletal muscle mass, as measured by computed tomography (CT). The clinical records of 1907 subjects (1406 males, mean age 53.1 ± 9.2 years), who underwent routine health check-ups, including spirometry and abdominal CT, were retrospectively reviewed. The CT-measured skeletal muscle index (SMI_CT, cm²/(kg/m²) was defined as the skeletal muscle area of the third lumbar vertebrae (L3) level that is normalized by the body mass index. The mean values of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) gradually increased as the SMI_CT quartiles increased (all p for trend < 0.05). The proportions of subjects with less than 80% of the predicted FVC (%) and predicted FEV1 (%) significantly decreased as the SMI_CT quartiles increased (all p for trend < 0.05). The β regression coefficients for FVC and FEV1 significantly increased as the SMI_CT quartiles increased after adjusting for other confounding variables (p for trend < 0.05). This study showed that abdominal muscle mass, which was precisely measured by CT, independently affected lung function proportionally after adjusting for confounding factors in relatively healthy adults.