MAFLD vs. NAFLD: shared features and potential changes in epidemiology, pathophysiology, diagnosis, and pharmacotherapy. Chin Med J (Engl). 2020;134:8-19. [PMID: 33323806 PMCID: PMC7862804 DOI: 10.1097/cm9.0000000000001263]

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.

Non-Laboratory-Based Simple Screening Model for Nonalcoholic Fatty Liver Disease in Patients with Type 2 Diabetes Developed Using Multi-Center Cohorts

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent cause of chronic liver disease worldwide. Type 2 diabetes mellitus (T2DM) is a risk factor that accelerates NAFLD progression, leading to fibrosis and cirrhosis. Thus, here we aimed to develop a simple model to predict the presence of NAFLD based on clinical parameters of patients with T2DM.

METHODS

A total of 698 patients with T2DM who visited five medical centers were included. NAFLD was evaluated using transient elastography. Univariate logistic regression analyses were performed to identify potential contributors to NAFLD, followed by multivariable logistic regression analyses to create the final prediction model for NAFLD.

RESULTS

Two NAFLD prediction models were developed, with and without serum biomarker use. The non-laboratory model comprised six variables: age, sex, waist circumference, body mass index (BMI), dyslipidemia, and smoking status. For a cutoff value of ≥60, the prediction accuracy was 0.780 (95% confidence interval [CI], 0.743 to 0.817). The second comprehensive model showed an improved discrimination ability of up to 0.815 (95% CI, 0.782 to 0.847) and comprised seven variables: age, sex, waist circumference, BMI, glycated hemoglobin, triglyceride, and alanine aminotransferase to aspartate aminotransferase ratio. Our non-laboratory model showed non-inferiority in the prediction of NAFLD versus previously established models, including serum parameters.

CONCLUSION

The new models are simple and user-friendly screening methods that can identify individuals with T2DM who are at high-risk for NAFLD. Additional studies are warranted to validate these new models as useful predictive tools for NAFLD in clinical practice.

Editorial: International Consensus Recommendations to Replace the Terminology of Non-Alcoholic Fatty Liver Disease (NAFLD) with Metabolic-Associated Fatty Liver Disease (MAFLD)

In 2020, international consensus guidelines recommended the renaming of non-alcoholic fatty liver disease (NAFLD) to metabolic-associated fatty liver disease (MAFLD), supported by diagnostic criteria. MAFLD affects up to 25% of the global population. However, the rates of MAFLD are likely to be underestimated due to the increasing prevalence of type 2 diabetes mellitus (T2DM) and obesity. Within the next decade, MAFLD has been projected to become a major cause of cirrhosis and hepatocellular carcinoma (HCC) worldwide, as well as the most common indication for liver transplantation in the US. This transition in terminology and clinical criteria may increase momentum and clinical evidence at multiple levels, including patient diagnosis, management, and care, and provide the basis for new research areas and clinical development for therapeutics. The diagnostic criteria for MAFLD are practical, simple, and superior to the existing NAFLD criteria for identifying patients at increased risk of developing progressive liver disease. This Editorial aims to present the historical evolution of the terminology for fatty liver disease and the advantages of diagnosis, patient management, and future research on MAFLD.

Links between metabolic syndrome and metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic condition characterized by hepatic fat accumulation combined with underlying metabolic dysregulation. Having evolved from the previous term of nonalcoholic fatty liver disease (NAFLD), the term MAFLD more closely implicates the presence of overweight/obesity, type 2 diabetes, or metabolic dysregulation as essential pathogenic factors, leading to better identification of individuals with this metabolic liver disease. Low-grade inflammation, increased oxidative stress, mitochondrial dysfunction, and intestinal dysbiosis are also involved in its pathogenesis. MAFLD is not only associated with liver-related complications, but also with adverse cardiometabolic outcomes. Further studies are needed to assess whether the newly proposed definition of MAFLD is more accurate than the NAFLD in predicting the adverse liver-related and extrahepatic outcomes.

Cardiovascular and renal burdens of metabolic associated fatty liver disease from serial US national surveys, 1999-2016

Background:

Non-communicable chronic diseases have become the leading causes of disease burden worldwide. The trends and burden of “metabolic associated fatty liver disease” (MAFLD) are unknown. We aimed to investigate the cardiovascular and renal burdens in adults with MAFLD and non-alcoholic fatty liver disease (NAFLD).

Methods:

Nationally representative data were analyzed including data from 19,617 non-pregnant adults aged ≥20 years from the cross-sectional US National Health and Nutrition Examination Survey periods, 1999 to 2002, 2003 to 2006, 2007 to 2010, and 2011 to 2016. MAFLD was defined by the presence of hepatic steatosis plus general overweight/obesity, type 2 diabetes mellitus, or evidence of metabolic dysregulation.

Results:

The prevalence of MAFLD increased from 28.4% (95% confidence interval 26.3–30.6) in 1999 to 2002 to 35.8% (33.8–37.9) in 2011 to 2016. In 2011 to 2016, among adults with MAFLD, 49.0% (45.8–52.2) had hypertension, 57.8% (55.2–60.4) had dyslipidemia, 26.4% (23.9–28.9) had diabetes mellitus, 88.7% (87.0–80.1) had central obesity, and 18.5% (16.3–20.8) were current smokers. The 10-year cardiovascular risk ranged from 10.5% to 13.1%; 19.7% (17.6–21.9) had chronic kidney diseases (CKDs). Through the four periods, adults with MAFLD showed an increase in obesity; increase in treatment to lower blood pressure (BP), lipids, and hemoglobin A1c; and increase in goal achievements for BP and lipids but not in goal achievement for glycemic control in diabetes mellitus. Patients showed a decreasing 10-year cardiovascular risk over time but no change in the prevalence of CKDs, myocardial infarction, or stroke. Generally, although participants with NAFLD and those with MAFLD had a comparable prevalence of cardiovascular disease and CKD, the prevalence of MAFLD was significantly higher than that of NAFLD.

Conclusions:

From 1999 to 2016, cardiovascular and renal risks and diseases have become highly prevalent in adults with MAFLD. The absolute cardiorenal burden may be greater for MAFLD than for NAFLD. These data call for early identification and risk stratification of MAFLD and close collaboration between endocrinologists and hepatologists.

Coronavirus disease 2019 severity in obesity: Metabolic dysfunction-associated fatty liver disease in the spotlight

The coronavirus disease 2019 (COVID-19) outbreak has drawn the scientific community's attention to pre-existing metabolic conditions that could aggravate the infection, causing extended viral shedding, prolonged hospitalization, and high death rates. Metabolic dysfunction-associated fatty liver disease (MAFLD) emerges as a surrogate for COVID-19 severity due to the constellation of metabolic alterations it entails. This review outlines the impact MAFLD exerts on COVID-19 severity in obese subjects, besides the possible mechanistic links to the poor outcomes. The data collected showed that MAFLD patients had poorer COVID-19 outcomes than non-MAFLD obese subjects. MAFLD is generally accompanied by impaired glycemic control and systemic arterial hypertension, both of which can decompensate during the COVID-19 clinical course. Also, MAFLD subjects had higher plasma inflammatory marker concentrations than non-MAFLD subjects, which might be related to an intensified cytokine storm syndrome frequently associated with the need for mechanical ventilation and death. In conclusion, MAFLD represents a higher risk than obesity for COVID-19 severity, resulting in poor outcomes and even progression to non-alcoholic steatohepatitis. Hepatologists should include MAFLD subjects in the high-risk group, intensify preventive measurements, and prioritize their vaccination.