Clinical utility of the MAFLD definition

Elevated concurrent carotid atherosclerosis rates in patients with metabolic dysfunction-associated fatty liver disease (MAFLD) compared to non-alcoholic fatty liver disease (NAFLD): A cross-sectional observational study

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) has been recognized as an independent risk factor for atherosclerotic cardiovascular disease. Recently, there has been a shift towards diagnosing metabolic dysfunction-associated fatty liver disease (MAFLD), offering simplified criteria and improved risk assessment. However, the association between MAFLD and carotid atherosclerosis remains poorly understood.

METHODS AND RESULTS

The study analyzed the association of concurrent carotid atherosclerosis between NAFLD and MAFLD patients with a retrospective cohort design. The study enrolled participants who underwent abdominal and carotid artery ultrasounds from a medical center in Taiwan. NAFLD and MAFLD were diagnosed based on imaging and specific criteria. Associations between NAFLD, MAFLD, and carotid atherosclerosis were analyzed using logistic regression. Among 11,194 participants, 57.1 % were diagnosed with fatty liver disease, among which the NAFLD-MAFLD group comprised 4689 individuals, with 900 in the NAFLD-only group and 669 in the MAFLD-only group. Significant demographic and clinical differences were observed between groups. Logistic regression showed that the MAFLD-NAFLD group and MAFLD-only group had significantly higher odds of concomitant carotid atherosclerosis. Among MAFLD patients, 65.5 % had concurrent carotid arteriosclerosis with an odds ratio of 2.35 compared to non-MAFLD patients. The odds ratios for variables in MAFLD patients, such as diabetes mellitus, Fibrosis-4(FIB-4), number of FIB-4 > 1.3, and number of NAFLD fibrosis score > -1.455 were all greater than 2.

CONCLUSIONS

MAFLD is associated with a higher prevalence of carotid atherosclerosis, compared to NAFLD. This suggests that MAFLD may serve as a significant risk factor for cardiovascular complications.

MAFLD as part of systemic metabolic dysregulation

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. In recent years, a new terminology and definition of metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed. Compared to the NAFLD definition, MAFLD better emphasizes the pathogenic role of metabolic dysfunction in the development and progression of this highly prevalent condition. Metabolic disorders, including overweight/obesity, type 2 diabetes mellitus (T2DM), atherogenic dyslipidemia and hypertension, are often associated with systemic organ dysfunctions, thereby suggesting that multiple organ damage can occur in MAFLD. Substantial epidemiological evidence indicates that MAFLD is not only associated with an increased risk of liver-related complications, but also increases the risk of developing several extra-hepatic diseases, including new-onset T2DM, adverse cardiovascular and renal outcomes, and some common endocrine diseases. We have summarized the current literature on the adverse effect of MAFLD on the development of multiple extrahepatic (cardiometabolic and endocrine) complications and examined the role of different metabolic pathways and organ systems in the progression of MAFLD, thus providing new insights into the role of MAFLD as a multisystem metabolic disorder. Our narrative review aimed to provide insights into potential mechanisms underlying the known associations between MAFLD and extrahepatic diseases, as part of MAFLD as a multisystem disease, in order to help focus areas for future drug development targeting not only liver disease but also the risk of extrahepatic complications.

Associating plasma aldosterone concentration with the prevalence of MAFLD in hypertensive patients: insights from a large-scale cross-sectional study

Objective

To explore the link between plasma aldosterone concentration (PAC) and the prevalence of metabolic dysfunction-related fatty liver disease (MAFLD) in hypertensive patients.

Methods

We analyzed data from 41,131 hospitalized patients from January 1, 2014, to December 31, 2023. Multivariate logistic regression models tested associations, with threshold, subgroup, and sensitivity analyses conducted to validate findings.

Results

For each 5-unit increase in PAC, the risk of MAFLD rose by 1.57 times, consistent even in the fully adjusted model. The odds ratios for the Q2, Q3, and Q4 groups compared to Q1 were 1.21, 2.12, and 3.14, respectively. A threshold effect was observed at 14 ng/dL, with subgroup and sensitivity analyses supporting these results.

Conclusions

This study reveals a significant positive association between elevated PAC levels and the prevalence of MAFLD in hypertensive patients. These findings underscore the imperative for further large-scale, prospective studies to validate and expand upon this correlation.

Metabolic dysfunction-associated steatotic liver disease and atherosclerosis

PURPOSE OF REVIEW

To update information about the relationship between metabolic dysfunction-associated steatotic liver disease (MASLD) and atherosclerosis. This review emphasizes the potential mechanisms linking MASLD with atherosclerosis and the possible causal relationships between these conditions.

RECENT FINDINGS

An increased risk of cardiovascular disease is related to MASLD. Several molecular, cellular, and metabolic mechanisms have been described to explain the development of atherothrombosis in MASLD patients. These include atherogenic dyslipidemia, low-grade vascular inflammation, endothelial dysfunction, foam cell formation, proliferation of vascular smooth muscle cells, insulin resistance, gut microbiota dysbiosis, activation of renin-angiotensin and sympathetic nervous systems, hypercoagulability, and decreased fibrinolysis. Also, there is recent evidence suggesting an association between genetically driven liver fat and coronary heart disease mediated by the causal effect of apoB-containing lipoproteins. Several meta-analyses and systematic reviews have reported a strong association between MASLD and cardiovascular outcomes. MASLD is an important and independent risk factor for atherosclerosis development. Multiple mechanisms may be involved in this association. Further research is required to establish a causal association between MASLD and atherosclerosis.

Recompensation in cirrhosis: unravelling the evolving natural history of nonalcoholic fatty liver disease

Recompensation has gained increasing attention in the field of cirrhosis, particularly in chronic liver disease with a definite aetiology. The current global prevalence of obesity and nonalcoholic fatty liver disease (NAFLD) is increasing, but there is currently a lack of a clear definition for recompensation in NAFLD-related cirrhosis. Here, we provide an up-to-date perspective on the natural history of NAFLD, emphasizing the reversible nature of the disease, summarizing possible mechanisms underlying recompensation in NAFLD, discussing challenges that need to be addressed and outlining future research directions in the field. Recompensation is a promising goal in patients with NAFLD-related cirrhosis, and further studies are needed to explore its underlying mechanisms and uncover its clinical features.

Prevalence of metabolic syndrome and metabolic dysfunction-associated fatty liver disease in Malaysia 2023: study protocol for a community-based nationwide cross-sectional survey

INTRODUCTION

Metabolic syndrome (MetS) is a cluster of cardio-metabolic dysfunctions characterised by increased fasting plasma glucose, waist circumference, blood pressure, triglycerides and reduction in high-density lipoprotein cholesterol. Meanwhile, metabolic dysfunction-associated fatty liver disease (MAFLD) is the new term for fatty liver associated with MetS. People with MetS or MAFLD have higher risks for adverse cardiovascular outcomes and mortalities. However, large-scale data on MetS and MAFLD prevalence in Malaysia is mainly unknown. This study aims to determine the prevalence of MetS and MAFLD among the general adult population in Malaysia.

METHODS AND ANALYSIS

This is a community-based nationwide cross-sectional study in Malaysia. The data collection period is from July 2023 until September 2023, with a planned sample size of 1296 participants. We use a two-stage proportionate stratified random sampling method to ensure national representativeness. The definition of MetS follows the Harmonised Joint Interim Statement in 2009. A diagnosis of MAFLD is made if a participant has fatty liver, defined as having a Fatty Liver Index ≥60 and has type 2 diabetes, a body mass index ≥23 kg/m2, or ≥2 metabolic risk abnormalities. Complex sample analysis will be conducted, and the disease prevalence will be reported with 95% CIs, unweighted counts and estimated populations.

ETHICS AND DISSEMINATION

The protocol has been approved by the Medical Research and Ethics Committee of the Ministry of Health Malaysia (NMRR ID-22-02845-GUT). The findings will be disseminated through a formal report, policy brief, scientific publications, conference presentations, social media, print media and stakeholder engagement activities.

Metabolic Dysfunction-Associated Fatty Liver Disease on Distinct Microbial Communities at the Bacterial Phylum Level

INTRODUCTION

Limited data are available on the correlation between microbial communities and metabolic dysfunction-associated fatty liver disease (MAFLD). This study aimed to evaluate the influence of MAFLD on diverse microbial communities.

METHODS

We recruited 43 patients with a nonviral liver disease. Enrolled patients were divided into two groups according to MAFLD criteria. The fecal microbial composition was evaluated using the variable V3-V4 region of the 16S ribosomal RNA region, which was amplified using polymerase chain reaction. First, we assessed the influence of MAFLD on distinct microbial communities at the bacterial phylum level. Next, the correlation between the microbial communities and diversity in patients with MAFLD was evaluated.

RESULTS

Among the enrolled participants, the non-MAFLD and MAFLD groups consisted of 21 and 22 patients, respectively. Sequences were distributed among ten bacterial phyla. The relative abundance of Firmicutes was significantly higher in the MAFLD group than in the non-MAFLD group (p = 0.014). The microbial diversity was not significantly influenced by the presence of MAFLD (Chao-1 index: p = 0.215 and Shannon index: p = 0.174, respectively); nonetheless, the correlation coefficient between the abundances of Firmicutes and microbial diversity was higher in the non-MAFLD group than in the MAFLD group.

CONCLUSION

The presence of MAFLD increased the relative abundances of Firmicutes at the bacterial phylum level, which may cause the discrepancy between the abundances of Firmicutes and diversity in patients with MAFLD.

An international multidisciplinary consensus statement on MAFLD and the risk of CVD

BACKGROUND

Fatty liver disease in the absence of excessive alcohol consumption is an increasingly common condition with a global prevalence of ~ 25-30% and is also associated with cardiovascular disease (CVD). Since systemic metabolic dysfunction underlies its pathogenesis, the term metabolic (dysfunction)-associated fatty liver disease (MAFLD) has been proposed for this condition. MAFLD is closely intertwined with obesity, type 2 diabetes mellitus and atherogenic dyslipidemia, which are established cardiovascular risk factors. Unlike CVD, which has received attention in the literature on fatty liver disease, the CVD risk associated with MAFLD is often underestimated, especially among Cardiologists.

METHODS AND RESULTS

A multidisciplinary panel of fifty-two international experts comprising Hepatologists, Endocrinologists, Diabetologists, Cardiologists and Family Physicians from six continents (Asia, Europe, North America, South America, Africa and Oceania) participated in a formal Delphi survey and developed consensus statements on the association between MAFLD and the risk of CVD. Statements were developed on different aspects of CVD risk, ranging from epidemiology to mechanisms, screening, and management.

CONCULSIONS

The expert panel identified important clinical associations between MAFLD and the risk of CVD that could serve to increase awareness of the adverse metabolic and cardiovascular outcomes of MAFLD. Finally, the expert panel also suggests potential areas for future research.

Comparison of Outcomes Between Metabolic Dysfunction-Associated Fatty Liver Disease and Non-alcoholic Fatty Liver Disease: A Meta-Analysis

Non-alcoholic fatty liver disease (NAFLD) encompasses a range of conditions, from fatty liver to cirrhosis. In response to evolving research and to better reflect the complex metabolic underpinnings, the term metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed. The aim of this meta-analysis was to compare cardiovascular events and all-cause mortality between NAFLD and MAFLD patients. The present study was conducted following the Preferred Reporting of Systematic Review and Meta-analysis (PRISMA) guidelines. We systematically searched PubMed, EMBASE, and the Web of Science to identify studies that compared cardiovascular outcomes in MAFLD and NAFLD from inception to July 31, 2023. Outcomes assessed in this meta-analysis included all-cause mortality, cardiovascular mortality, and cardiovascular events. A total of 11 studies were included in this meta-analysis. The risk of cardiovascular mortality was significantly higher in patients with MAFLD patients compared to NAFLD patients (risk ratio (RR): 1.48, 95% confidence interval (CI): 1.11 to 1.98). The risk of all-cause mortality was higher in MAFLD patients compared to NAFLD, and the difference was statistically significant (RR: 2.80, 95% CI: 2.39 to 3.28). The risk of cardiovascular events was significantly higher in MAFLD patients compared to NAFLD (RR: 1.18, 95% CI: 0.86 to 1.61). The key findings underscore that individuals diagnosed with MAFLD face a notably higher risk of all-cause mortality, cardiovascular mortality, and cardiovascular events when compared to those with NAFLD.

Problems and Challenges Associated with Renaming Non-alcoholic Fatty Liver Disease to Metabolic Associated Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) has become the world’s largest chronic liver disease in the 21st century, affecting 20%–30% of the world’s population. As the epidemiology, etiology, and pathogenesis of NAFLD have been studied in-depth, it has been gradually recognized that most patients with NAFLD have one or more combined metabolic abnormalities known as metabolic syndrome. In 2020, the international expert group changed the name of NAFLD to metabolic-associated fatty liver disease (MAFLD) and proposed new diagnostic criteria for MAFLD and MAFLD-related liver cirrhosis, as well as the conceptual framework of other cause-related fatty liver diseases to avoid diagnosis based on the exclusion of other causes and better reflect its pathogenesis. However, there are still many ambiguities in the term, and changing the name does not address the unmet key needs in the field. The change from NAFLD to MAFLD was not just a change of definition. The problems and challenges are summarized as follows: epidemiology, children, rationality of “metabolism,” diagnostic criteria, double/multiple causes, drug discovery, clinical trials, and awareness raising. Metabolic-associated fatty liver disease has complex disease characteristics, and there are still some problems that need to be solved.

Characteristics of gut microbiota in patients with metabolic associated fatty liver disease

Metabolic associated fatty liver disease (MAFLD) is rising in incidence and is an increasingly common cause of cirrhosis and hepatocellular carcinoma (HCC). Alterations in the gut microbiota have been shown to correlate with the development and progression of MAFLD. However, little is known regarding differences in the gut microbiomes of MAFLD patients and healthy cohorts, and subgroups at the abnormal activity of hepatic enzymes in China. In this study, we enrolled 81 MAFLD patients and 25 healthy volunteers. The fecal microbiota was assessed using 16S rRNA gene sequencing and metagenomic sequencing. The results suggested that Ruminococcus obeum and Alistipes were most enriched in healthy individuals when compared with MAFLD patients. Microbe-set Enrichment Analysis (MSEA) results showed Dorea, Lactobacillus and Megasphaera are enriched in MAFLD group. We also found that Alistipes has negatively related to serum glucose (GLU), gamma-glutamyl transferase (GGT), and alanine aminotransferase (ALT). Moreover, the abundance of Dorea was found to be significantly overrepresented in the MAFLD patients and the degree of enrichment increased with the increasing abnormal liver enzyme. An increase in Dorea, combined with decreases in Alistipes appears to be characteristic of MAFLD patients. Further study of microbiota may provide a novel insight into the pathogenesis of MAFLD as well as a novel treatment strategy.

An international Delphi consensus statement on metabolic dysfunction-associated fatty liver disease and risk of chronic kidney disease

BACKGROUND

With the rising global prevalence of fatty liver disease related to metabolic dysfunction, the association of this common liver condition with chronic kidney disease (CKD) has become increasingly evident. In 2020, the more inclusive term metabolic dysfunction-associated fatty liver disease (MAFLD) was proposed to replace the term non-alcoholic fatty liver disease (NAFLD). The observed association between MAFLD and CKD and our understanding that CKD can be a consequence of underlying metabolic dysfunction support the notion that individuals with MAFLD are at higher risk of having and developing CKD compared with those without MAFLD. However, to date, there is no appropriate guidance on CKD in individuals with MAFLD. Furthermore, there has been little attention paid to the link between MAFLD and CKD in the Nephrology community.

METHODS AND RESULTS

Using a Delphi-based approach, a multidisciplinary panel of 50 international experts from 26 countries reached a consensus on some of the open research questions regarding the link between MAFLD and CKD.

CONCLUSIONS

This Delphi-based consensus statement provided guidance on the epidemiology, mechanisms, management and treatment of MAFLD and CKD, as well as the relationship between the severity of MAFLD and risk of CKD, which establish a framework for the early prevention and management of these two common and interconnected diseases.

Comparison of cardiovascular mortality between MAFLD and NAFLD: A cohort study

BACKGROUND AND AIMS

A new diagnostic criterion of metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed. However, only few studies have shown that MAFLD predicts cardiovascular disease (CVD) mortality better than non-alcoholic fatty liver disease (NAFLD). Therefore, a cohort study was conducted to assess this relationship.

METHODS AND RESULTS

Health examination data from health care centers in South Korea were assessed after excluding participants with missing covariates and cancer history (n = 701,664). Liver ultrasonography reports, laboratory and anthropometric data were extracted. Diagnoses of NAFLD and MAFLD were performed according to standard definitions. Participants were categorized based on the presence of NAFLD and MAFLD. In addition, participants were classified into five categories: no fatty liver disease (no FLD), NAFLD-only, MAFLD-only, both FLDs, and alcoholic FLD (AFLD) and non-MAFLD. Multivariable regression modeling was performed. The median follow-up duration was 8.77 years, and 52.56% of participants were men. After stratifying the cohort into no-MAFLD and MAFLD groups, MAFLD was associated with increased CVD mortality (adjusted HR 1.14, 95% CI 1.02-1.28). When participants were divided into no-NAFLD and NAFLD groups, there was a non-significant trend towards an increase in CVD mortality in NAFLD group (adjusted HR 1.07, 95% CI 0.95-1.21). When participants were divided into five categories, MAFLD-only group showed increased CVD mortality (adjusted HR 1.35, 95% CI 1.07-1.70) while NAFLD-only group showed no significant association with CVD mortality (adjusted HR 0.67, 95% CI 0.38-1.19).

CONCLUSIONS

In conclusion, MAFLD is associated with increased CVD mortality in a relatively young Korean population.

N-terminal propeptide of type 3 collagen-based sequential algorithm can identify high-risk steatohepatitis and fibrosis in MAFLD

BACKGROUND AND AIMS

With metabolic dysfunction-associated fatty liver disease (MAFLD) incidence and prevalence sharply increasing globally, there is an urgent need for non-invasive diagnostic tests to accurately screen high-risk MAFLD patients for liver inflammation and fibrosis. We aimed to develop a novel sequential algorithm based on N-terminal propeptide of type 3 collagen (PRO-C3) for disease risk stratification in patients with MAFLD.

METHODS

A derivation and independent validation cohort of 327 and 142 patients with biopsy-confirmed MAFLD were studied. We compared the diagnostic performances of various non-invasive scores in different disease states, and a novel sequential algorithm was constructed by combining the best performing non-invasive scores.

RESULTS

For patients with high-risk progressive steatohepatitis (i.e., steatohepatitis + NAFLD activity score ≥ 4 + F ≥ 2), the AUROC of FAST score was 0.801 (95% confidence interval (CI): 0.739-0.863), and the negative predictive value (NPV) was 0.951. For advanced fibrosis (≥ F3) and cirrhosis (F4), the AUROCs of ADAPT and Agile 4 were 0.879 (95%CI 0.825-0.933) and 0.943 (95%CI 0.892-0.994), and the NPV were 0.972 and 0.992. Sequential algorithm of ADAPT + Agile 4 combination was better than other combinations for risk stratification of patients with severe fibrosis (AUROC = 0.88), with similar results in the validation cohort. Meanwhile, in all subgroup analyses (stratifying by sex, age, diabetes, NAS, BMI and ALT), ADAPT + Agile 4 had a good diagnostic performance.

CONCLUSIONS

The new sequential algorithm reliably identifies liver inflammation and fibrosis in MAFLD, making it easier to exclude low-risk patients and recommending high-risk MAFLD patients for clinical trials and emerging pharmacotherapies.

MAFLD: How is it different from NAFLD?

"Metabolic dysfunction-associated fatty liver disease (MAFLD)" is the term suggested in 2020 to refer to fatty liver disease related to systemic metabolic dysregulation. The name change from nonalcoholic fatty liver disease (NAFLD) to MAFLD comes with a simple set of criteria to enable easy diagnosis at the bedside for the general medical community, including primary care physicians. Since the introduction of the term, there have been key areas in which the superiority of MAFLD over the traditional NAFLD terminology has been demonstrated, including for the risk of liver and extrahepatic mortality, disease associations, and for identifying high-risk individuals. Additionally, MAFLD has been adopted by a number of leading pan-national and national societies due to its concise diagnostic criterion, removal of the requirement to exclude concomitant liver diseases, and reduction in the stigma associated with this condition. The current article explores the differences between MAFLD and NAFLD diagnosis, areas of benefit, some potential limitations, and how the MAFLD terminology has opened up new fields of research.

Type 2 diabetes mellitus in metabolic-associated fatty liver disease vs. type 2 diabetes mellitus non-alcoholic fatty liver disease: a longitudinal cohort analysis

INTRODUCTION AND OBJECTIVES

Type 2 Diabetes Mellitus (T2DM) is comorbidity commonly presenting with fatty liver. A recently proposed definition of "metabolic associated fatty liver disease" (MAFLD) is thought to replace non-alcoholic fatty liver disease (NAFLD). Yet, despite the significant prevalence of T2DM among fatty liver, there remains limited evidence on the impact of the change in the definition of T2DM.

MATERIALS AND METHODS

The current study uses data from the United States National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. Survival analysis was conducted with a cox regression and sub-distribution hazard ratio for competing risk events.

RESULTS

6727 patients had a diagnosis of T2DM. 4982 individuals with T2DM had MAFLD and 2032 were MAFLD(+)/NAFLD(-), while 2950 patients were MAFLD(+)/NAFLD(+). The new definition increased fatty liver diagnosis by 68.89%. Patients who were classified as MAFLD(+)/NAFLD(-) were at a higher risk of major adverse cardiovascular events, advanced fibrosis, all-cause and cardiovascular-related mortality compared to MAFLD(+)/NAFLD(+). In MAFLD(+)/NAFLD(-), viral hepatitis significantly increases the odds of advanced fibrosis (OR: 6.77, CI: 3.92 to 11.7, p < 0.001) and all-cause mortality (HR: 1.75, CI: 1.29 to 2.40, p < 0.001).

CONCLUSIONS

The identification and treatment of NAFLD in patients with T2DM is a major concern and the premature change to MAFLD results in an over-diagnosis of fatty liver, exaggerated mortality, and morbidity in patients with T2DM. The definition of MAFLD causes further heterogeneity in fatty liver disease/NAFLD.

Metabolic-associated fatty liver disease and the risk of cardiovascular disease

BACKGROUND

With the gradual adoption of new metabolic-associated fatty liver disease (MAFLD) definitions in clinical practice, the relationship between MAFLD and cardiovascular disease (CVD) risk remains unclear. Similarly, clinical differences between MAFLD and nonalcoholic fatty liver disease (NAFLD), and the relationship between MAFLD and CVD risk are unclear.

METHODS

We conducted a retrospective study using the 1988-1994 National Health and Nutrition Examination Surveys (NHANES III) database, including 11,673 individuals. Multivariate logistic regression analysis was performed to test relationships between MAFLD and the 10-year CVD risk.

RESULTS

MAFLD was more significant than NAFLD in medium/high 10-year CVD risk (according to Framingham risk score) (1064 (29.92%) vs. 1022 (26.37%), P < 0.005). MAFLD patients were stratified according to NAFLD fibrosis scores (NFS's). In univariate regression analysis, when compared with non-MAFLD patients, unadjusted-OR values for MAFLD with different liver fibrosis stages, which were tiered by NFS (NFS < -1.455,-1.455 ≤ NFS < 0.676, and NFS ≥ 0.676) in the medium 10-year CVD risk (according to Framingham scores) were 1.175 (95% CI 1.030-1.341), 3.961 (3.449-4.549), and 5.477 (4.100-7.315), and the unadjusted or values of different MAFLD groups in the high 10-year CVD risk were 1.407 (95% CI 1.080-1.833), 5.725 (4.500-7.284), and 5.330 (3.132-9.068). Then, after adjusting for age, sex, race, alcohol consumption, and smoking, or adjusting for age, race, alcohol consumption, smoking, type 2 diabetes mellitus (T2DM), and other confounding factors, the incidence of medium and high 10-year CVD risk was statistically significant (P < 0.05).

CONCLUSIONS

We showed that patients with MAFLD had a higher 10-year CVD risk when compared with patients with NAFLD. Increased MAFLD hepatic fibrosis scores were associated with a 10-year CVD risk.

Metabolic dysfunction-associated fatty liver disease and implications for cardiovascular risk and disease prevention

The newly proposed term "metabolic dysfunction-associated fatty liver disease" (MAFLD) is replacing the old term "non-alcoholic fatty liver disease" (NAFLD) in many global regions, because it better reflects the pathophysiology and cardiometabolic implications of this common liver disease. The proposed change in terminology from NAFLD to MAFLD is not simply a single-letter change in an acronym, since MAFLD is defined by a set of specific and positive diagnostic criteria. In particular, the MAFLD definition specifically incorporates within the classification recognized cardiovascular risk factors. Although convincing evidence supports a significant association between both NAFLD and MAFLD, with increased risk of CVD morbidity and mortality, neither NAFLD nor MAFLD have received sufficient attention from the Cardiology community. In fact, there is a paucity of scientific guidelines focusing on this common and burdensome liver disease from cardiovascular professional societies. This Perspective article discusses the rationale and clinical relevance for Cardiologists of the newly proposed MAFLD definition.

Hepatic steatosis leads to overestimation of liver stiffness measurement in both chronic hepatitis B and metabolic-associated fatty liver disease patients

BACKGROUND

The impact of hepatic steatosis on liver stiffness measurement (LSM) in both chronic hepatitis B(CHB) and metabolic-associated fatty liver disease (MAFLD) remains controversial.

AIMS

To determine whether LSM is affected by hepatic steatosis in CHB-MAFLD.

METHODS

Hepatic steatosis and liver fibrosis were assessed by histological and noninvasively methods. The area under the receiver operating characteristic curve (AUROC) was used to evaluate the diagnostic performance of LSM.

RESULTS

The prevalence of MAFLD in CHB patients (n = 436)was 47.5% (n = 207). For patients with low amounts of fibrosis (F0-1 and F0-2), the median LSM was 8.8 kPa and 9.2 kPa in patients with moderate- severe steatosis,which was significantly higher than that in patients with none-mild steatosis (P < 0.05) . The positive predictive value(PPV) was lower for LSM identifying significant fibrosis (F ≥ 2) as well as severe fibrosis (F ≥ 3) in group which controlled attenuation parameter(CAP) ≥ 268 dB/m than its counterpart(68.2% vs 84.6% and 24.3% vs 45.0%). The AUROC of LSM detected F ≥ 2 was 0.833 at a cutoff of 8.8 kPa and 0.873 at a cutoff of 7.0 kPa in patients with CAP ≥ 268 and CAP < 268, respectively.

CONCLUSIONS

The presence of moderate-severe steatosis, detected by histology or CAP, should be taken into account to avoid overestimation of LSM.

Nonalcoholic fatty liver disease versus metabolic-associated fatty liver disease: Prevalence, outcomes and implications of a change in name

Nonalcoholic fatty liver disease (NAFLD) affects about a third of the world's adult population and is a major public health concern. NAFLD is defined by the presence of hepatic steatosis and the absence of other causes of liver disease. As NAFLD is closely associated with the presence of the metabolic syndrome, several experts have called for a change in nomenclature from NAFLD to metabolic-associated fatty liver disease (MAFLD) to better reflect the underlying pathophysiology of NAFLD as a metabolically driven disease and shift to a "positive" diagnostic criteria rather than one of exclusion. Recent studies have suggested that the global prevalence of MAFLD is higher than that of NAFLD, and patients with MAFLD have more metabolic comorbidities compared to those with NAFLD. Emerging data also suggest that all-cause and cardiovascular mortality may be higher in MAFLD compared with NAFLD. In this synopsis, we discuss differences in clinical features, prevalence and clinical outcomes between NAFLD and MAFLD. In addition, we highlight the advantages and disadvantages of a name change from NAFLD to MAFLD from the perspective of the scientific community, care providers and patients.

Old and new classes of glucose-lowering agents as treatments for non-alcoholic fatty liver disease: A narrative review

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease with a global prevalence of about 55% in people with type 2 diabetes mellitus (T2DM). T2DM, obesity and NAFLD are three closely inter-related pathological conditions. In addition, T2DM is one of the strongest clinical risk factors for the faster progression of NAFLD to non-alcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma. Increasing evidence suggests that newer classes of glucose-lowering drugs, such as peroxisome proliferator-activated receptor agonists, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors or sodium-glucose cotransporter-2 inhibitors, could reduce the rates of NAFLD progression. This narrative review aims to briefly summarize the recent results from randomized controlled trials testing the efficacy and safety of old and new glucose-lowering drugs for the treatment of NAFLD or NASH in adults both with and without coexisting T2DM.

Recent advances in lean NAFLD

As the predominant type of chronic liver disease, the growing prevalence of nonalcoholic fatty liver disease (NAFLD) has become a concern worldwide. Although obesity plays the most pivotal role in NAFLD, approximately 10-20% of individuals with NAFLD who are not overweight or obese (BMI < 25 kg/m2, or BMI < 23 kg/m2 in Asians) have "lean NAFLD." Lean individuals with NAFLD have a lower prevalence of diabetes, hypertension, hypertriglyceridemia, central obesity, and metabolic syndrome than nonlean individuals with NAFLD, but higher fibrosis scores and rates of cardiovascular morbidity and all-cause mortality in advanced stages. The pathophysiological mechanisms of lean NAFLD remain poorly understood. Studies have shown that lean NAFLD is more correlated with factors such as environmental, genetic susceptibility, and epigenetic regulation. This review will examine the way in which the research progress and characteristic of lean NAFLD, and explore the function of epigenetic modification to provide the basis for the clinical treatment and diagnosis of lean NAFLD.

SEMA7AR148W mutation promotes lipid accumulation and NAFLD progression via increased localization on the hepatocyte surface

Genetic polymorphisms are associated with the development of nonalcoholic fatty liver disease (NAFLD). Semaphorin7a (Sema7a) deficiency in mouse peritoneal macrophages reduces fatty acid (FA) oxidation. Here, we identified 17 individuals with SEMA7A heterozygous mutations in 470 patients with biopsy-proven NAFLD. SEMA7A heterozygous mutations increased susceptibility to NAFLD, steatosis severity, and NAFLD activity scores in humans and mice. The Sema7aR145W mutation (equivalent to human SEMA7AR148W) significantly induced small lipid droplet accumulation in mouse livers compared with WT mouse livers. Mechanistically, the Sema7aR145W mutation increased N-glycosylated Sema7a and its receptor integrin β1 proteins in the cell membranes of hepatocytes. Furthermore, Sema7aR145W mutation enhanced its protein interaction with integrin β1 and PKC-α and increased PKC-α phosphorylation, which were both abrogated by integrin β1 silencing. Induction of PKCα_WT, but not PKCα_dominant negative, overexpression induced transcriptional factors Srebp1, Chrebp, and Lxr expression and their downstream Acc1, Fasn, and Cd36 expression in primary mouse hepatocytes. Collectively, our findings demonstrate that the SEMA7AR148W mutation is a potentially new strong genetic determinant of NAFLD and promotes intrahepatic lipid accumulation and NAFLD in mice by enhancing PKC-α-stimulated FA and triglyceride synthesis and FA uptake. The inhibition of hepatic PKC-α signaling may lead to novel NAFLD therapies.

Ferroptosis and metabolic dysfunction-associated fatty liver disease: Is there a link?

Non-alcoholic fatty liver disease (NAFLD), recently re-defined and re-classified as metabolic dysfunction-associated fatty liver disease (MAFLD), has become increasingly prevalent and emerged as a public health problem worldwide. To date, the precise pathogenic mechanisms underpinning MAFLD are not entirely understood, and there is no effective pharmacological therapy for NAFLD/MAFLD. As a newly discovered form of iron-dependent programmed cell death, ferroptosis can be involved in the development and progression of various chronic diseases, but the pathogenic connections and mechanisms that link MAFLD and ferroptosis have not been fully elucidated. The main characteristics of ferroptosis are the accumulation of lipid peroxides and reactive oxygen species. In this brief narrative review, the mechanisms of ferroptosis and its putative pathogenic role in MAFLD are discussed to highlight potential new research directions and ideas for the prevention and treatment of MAFLD.

SGLT-2 inhibitors and GLP-1 receptor agonists in metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic condition that affects nearly one billion people globally, characterized by triacylglycerol accumulation in the liver as a consequence of metabolic abnormalities (obesity and impaired glucose regulation). Low-grade inflammation, oxidative stress, mitochondrial dysfunction, and dysbiosis in gut microbiota are involved in the etiology of MAFLD, and both cardiovascular events and hepatic complications are the long-term consequences. In the absence of approved therapies for this condition, sodium-glucose cotransporter 2 inhibitors (SGLT-2 Is) and glucagon-like peptide 1 receptor agonists (GLP-1 RAs) have the specific advantage of lowering body weight and providing cardiovascular benefits. Here, we discuss potential roles for SGLT-2 Is and GLP-1 RAs in the prevention and treatment of intrahepatic triacylglycerol accumulation and associated inflammation and/or fibrosis.

Bile acids and sphingolipids in non-alcoholic fatty liver disease

ABSTRACT

Non-alcoholic fatty liver disease (NAFLD) is one of the fastest-growing diseases, and its global prevalence is estimated to increase >50% by 2030. NAFLD is comorbid with metabolic syndrome, obesity, type 2 diabetes, and insulin resistance. Despite extensive research efforts, there are no pharmacologic or biological therapeutics for the treatment of NAFLD. Bile acids and sphingolipids are well-characterized signaling molecules. Over the last few decades, researchers have uncovered potential mechanisms by which bile acids and sphingolipids regulate hepatic lipid metabolism. Dysregulation of bile acid and sphingolipid metabolism has been linked to steatosis, inflammation, and fibrosis in patients with NAFLD. This clinical observation has been recapitulated in animal models, which are well-accepted by experts in the hepatology field. Recent transcriptomic and lipidomic studies also show that sphingolipids are important players in the pathogenesis of NAFLD. Moreover, the identification of bile acids as activators of sphingolipid-mediated signaling pathways established a novel theory for bile acid and sphingolipid biology. In this review, we summarize the recent advances in the understanding of bile acid and sphingolipid-mediated signaling pathways as potential contributors to NAFLD. A better understanding of the pathologic effects mediated by bile acids and sphingolipids will facilitate the development of new diagnostic and therapeutic strategies for NAFLD.

Renaming NAFLD to MAFLD: Advantages and Potential Changes in Diagnosis, Pathophysiology, Treatment, and Management

Abstract

In recent years, with the increasing incidence of obesity and other metabolic diseases, the prevalence of non-alcoholic fatty liver disease (NAFLD) has increased and it has become a major health problem affecting more than one quarter of the world's population. Recently, experts reached a consensus that NAFLD does not reflect the current knowledge, and metabolic dysfunction-associated fatty liver disease (MAFLD) was suggested as a more appropriate term. MAFLD is not just a simple renaming of NAFLD. The definition of MAFLD allows a patient to have dual (or more) etiologies for their liver disease, which will help to exclude more heterogeneous patients. In this review, we introduce the significant differences between the definitions of NAFLD and MAFLD. In addition, we also describe the advantages of the term MAFLD in the pathophysiology, therapy, and patient management.

Malaysian Society of Gastroenterology and Hepatology consensus statement on metabolic dysfunction-associated fatty liver disease

The Malaysian Society of Gastroenterology and Hepatology saw the need for a consensus statement on metabolic dysfunction-associated fatty liver disease (MAFLD). The consensus panel consisted of experts in the field of gastroenterology/hepatology, endocrinology, bariatric surgery, family medicine, and public health. A modified Delphi process was used to prepare the consensus statements. The panel recognized the high and increasing prevalence of the disease and the consequent anticipated increase in liver-related complications and mortality. Cardiovascular disease is the leading cause of mortality in MAFLD patients; therefore, cardiovascular disease risk assessment and management is important. A simple and clear liver assessment and referral pathway was agreed upon, so that patients with more severe MAFLD can be linked to gastroenterology/hepatology care, while patients with less severe MAFLD can remain in primary care or endocrinology, where they are best managed. Lifestyle intervention is the cornerstone in the management of MAFLD. The panel provided a consensus on the use of statin, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, sodium-glucose cotransporter-2 inhibitor, glucagon-like peptide-1 agonist, pioglitazone, vitamin E, and metformin, as well as recommendations on bariatric surgery, screening for gastroesophageal varices and hepatocellular carcinoma, and liver transplantation in MAFLD patients. Increasing the awareness and knowledge of the various stakeholders on MAFLD and incorporating MAFLD into existing noncommunicable disease-related programs and activities are important steps to tackle the disease. These consensus statements will serve as a guide on MAFLD for clinicians and other stakeholders.

J-shaped relationship between serum zinc levels and the severity of hepatic necro-inflammation in patients with MAFLD

BACKGROUND AND AIMS

Zinc is an essential trace element that plays an important role in maintaining health, and affecting gene expression, signal transduction and regulation of apoptosis. It is uncertain whether serum zinc levels are altered in patients with metabolic dysfunction-associated fatty liver disease (MAFLD). We aimed to investigate the association between serum zinc levels and the severity of hepatic necro-inflammation (HN) in patients with MAFLD.

METHODS AND RESULTS

Liver disease severity was graded histologically using the NAFLD activity score. HN was defined as the sum of ballooning and lobular inflammation. We used a smooth function regression model to analyze the relationship between serum zinc levels and HN. A total of 561 (76.5% men) patients with biopsy-confirmed MAFLD were enrolled. They had a mean age of 41.3 years, and a mean serum zinc level of 17.0 ± 4.1 μmol/L. Compared to those with mild hepatic necro-inflammation (MHN, grades 0-2; n = 286), patients with severe hepatic necro-inflammation (SHN, grades 3-5; n = 275) had lower serum zinc concentrations (16.3 ± 4.2 vs. 17.6 ± 4.0 μmol/L; p < 0.001). However, a threshold saturation effect analysis showed that there was an inflection in serum zinc levels at 24 μmol/L. After adjustment for potential confounders, serum zinc levels <24 μmol/L were inversely associated with SHN (adjusted-odds ratio 0.88, 95%CI 0.83-0.93; p < 0.001), whereas serum zinc levels >24 μmol/L were positively associated with SHN (adjusted-odds ratio 1.42, 95%CI: 1.03-1.97; p = 0.035).

CONCLUSIONS

There is a J-shaped relationship between serum zinc levels and the severity of hepatic necro-inflammation in patients with biopsy-proven MAFLD.

Metabolic Dysfunction-associated Fatty Liver Disease is Associated with Greater Impairment of Lung Function than Nonalcoholic Fatty Liver Disease

BACKGROUND AND AIMS

We compared lung function parameters in nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated fatty liver disease (MAFLD), and examined the association between lung function parameters and fibrosis severity in MAFLD.

METHODS

In this cross-sectional study, we randomly recruited 2,543 middle-aged individuals from 25 communities across four cities in China during 2016 and 2020. All participants received a health check-up including measurement of anthropometric parameters, biochemical variables, liver ultrasonography, and spirometry. The severity of liver disease was assessed by the fibrosis (FIB)-4 score.

RESULTS

The prevalence of MAFLD was 20.4% (n=519) and that of NAFLD was 18.4% (n=469). After adjusting for age, sex, adiposity measures, smoking status, and significant alcohol intake, subjects with MAFLD had a significantly lower predicted forced vital capacity (FVC, 88.27±17.60% vs. 90.82±16.85%, p<0.05) and lower 1 s forced expiratory volume (FEV1, 79.89±17.34 vs. 83.02±16.66%, p<0.05) than those with NAFLD. MAFLD with an increased FIB-4 score was significantly associated with decreased lung function. For each 1-point increase in FIB-4, FVC was diminished by 0.507 (95% CI: -0.840, -0.173, p=0.003), and FEV1 was diminished by 0.439 (95% CI: -0.739, -0.140, p=0.004). The results remained unchanged when the statistical analyses was performed separately for men and women.

CONCLUSIONS

MAFLD was significantly associated with a greater impairment of lung function parameters than NAFLD.

Characterization of microbiome and metabolite analyses in patients with metabolic associated fatty liver disease and type II diabetes mellitus

Background

State-of-the-art renewal has indicated the improvement of diagnostics of patients with metabolic associated fatty liver disease (MAFLD) and/or type II diabetes mellitus (T2DM) by dissecting the clinical characteristics as well as genomic analysis. However, the deficiency of the characterization of microbial and metabolite signatures largely impedes the symptomatic treatment.

Methods

For the purpose, we retrospectively analyzed the clinical data of 20 patients with MAFLD (short for “M”), 20 cases with MAFLD and T2DM (short for “MD”), together with 19 healthy donors (short for “Ctr”). Microbial and metabolite analyses were further conducted to explore the similarities and differences among the aforementioned populations based on feces and blood samples, respectively.

Results

Compared with those in the Ctr group, patients with M or MD revealed multifaceted similarities (e.g., Age, ALP, LDL, BUN) and distinctions in clinical indicators of liver (e.g., BMI, ALT, PCHE, CAP). With the aid of microbial and metabolite analyses as well as bioinformatic analyses, we found that the characteristics of gut microbiota (e.g., abundance, hierarchical clustering, cladogram, species) and lipid metabolism (e.g., metabolite, correlation coefficient and scatter plot) were distinct among the indicated groups.

Conclusions

The patients with MD revealed multifaceted similarities and distinctions in characteristics of microbiome and metabolites with those in the M and HD groups, and in particular, the significantly expressed microbes (e.g., Elusimicrobiota, Berkelbacteria, Cyanobacteria, Peregrinibacteria) and lipid metabolites (e.g., Lipid-Q-P-0765, Lipid-Q-P-0216, Lipid-Q-P-0034, Lipid-Q-P-0800), which would collectively benefit the clinical diagnosis of MAFLD and T2DM.

Association of metabolic dysfunction-associated fatty liver disease with kidney disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of fat in more than 5% of hepatocytes in the absence of excessive alcohol consumption and other secondary causes of hepatic steatosis. In 2020, the more inclusive term metabolic (dysfunction)-associated fatty liver disease (MAFLD) - defined by broader diagnostic criteria - was proposed to replace the term NAFLD. The new terminology and revised definition better emphasize the pathogenic role of metabolic dysfunction and uses a set of definitive, inclusive criteria for diagnosis. Diagnosis of MAFLD is based on evidence of hepatic steatosis (as assessed by liver biopsy, imaging techniques or blood biomarkers and scores) in persons who are overweight or obese and have type 2 diabetes mellitus or metabolic dysregulation, regardless of the coexistence of other liver diseases or excessive alcohol consumption. The known association between NAFLD and chronic kidney disease (CKD) and our understanding that CKD can occur as a consequence of metabolic dysfunction suggests that individuals with MAFLD - who by definition have fatty liver and metabolic comorbidities - are at increased risk of CKD. In this Perspective article, we discuss the clinical associations between MAFLD and CKD, the pathophysiological mechanisms by which MAFLD may increase the risk of CKD and the potential drug treatments that may benefit both conditions.

Among simple non-invasive scores, Pro-C3 and ADAPT best exclude advanced fibrosis in Asian patients with MAFLD

BACKGROUND

With metabolic dysfunction-associated fatty liver disease (MAFLD) incidence and prevalence increasing, it is necessary to identify patients with advanced fibrosis (F3-F4 stages). We evaluated the performance of new biomarkers and algorithms for diagnosing advanced fibrosis in an Asian population.

METHODS

Data from two Asian cohorts (including 851 biopsy-proven MAFLD [578 from Wenzhou, 273 from Hong Kong]) were studied. The association between N-terminal propeptide of type 3 collagen (PRO-C3) and the histologic stage of liver fibrosis was analyzed by multivariable linear regression. The area under the receiver operating characteristic curve (AUROC) was used to test the diagnostic performance of serum PRO-C3 and the ADAPT score for advanced fibrosis and compared them to other established non-invasive tests.

RESULTS

Serum PRO-C3 levels increased progressively across liver fibrosis stages and correlated with advanced fibrosis (P < 0.001). The ADAPT score had an AUROC of 0.865 (95% confidence interval 0.829-0.901) for advanced fibrosis; the accuracy, sensitivity and negative predictive values were 81.4%, 82.2% and 96.1%, respectively. This result was better compared to that of PRO-C3 alone or other non-invasive fibrosis biomarkers (aspartate aminotransferase-to-platelet ratio index, Fibrosis-4, BARD, and NAFLD fibrosis score). In subgroup analyses (including sex, age, diabetes, NAFLD activity score, body mass index or serum alanine aminotransferase levels), the ADAPT score had good diagnostic performance.

CONCLUSION

PRO-C3 and the ADAPT score reliably exclude advanced fibrosis in MAFLD patients and reduce the need for liver biopsy.

Systematically comparing epidemiological and clinical features of MAFLD and NAFLD by meta-analysis: Focusing on the non-overlap groups

BACKGROUND & AIMS

The applicability of the novel metabolic dysfunction associated fatty liver disease (MAFLD) definition has been studied in numerous cohorts and compared to non-alcoholic fatty liver disease (NAFLD). No consensus has been reached on which definition is preferred. Therefore, this meta-analysis aims to compare the epidemiological and clinical features of NAFLD and MAFLD in the general and non-general population.

METHODS

We searched Medline, Embase and Web of Science for studies comparing MAFLD to NAFLD. Based on MAFLD and NAFLD status, the following subgroups were investigated for liver health: overlap fatty liver disease (FLD), NAFLD-only and MAFLD-only. Data were pooled using random-effects models.

RESULTS

We included 17 studies comprising 9 808 677 individuals. In the general population, MAFLD was present in 33.0% (95% CI 29.7%-36.5%) and NAFLD in 29.1% (95% CI 27.1%-31.1%). Among those with FLD, 4.0% (95% CI 2.4%-6.4%) did not meet the MAFLD criteria but had NAFLD (NAFLD-only) and 15.1% (95% CI 11.5%-19.5%) was exclusively captured by the novel MAFLD definition (MAFLD-only). Notably, this MAFLD-only group was at significantly increased risk for fibrosis (RR 4.2; 95% CI 1.3-12.9) and had higher alanine aminotransferase (mean difference: 8.0 U/L, 95% CI 2.6-13.5) and aspartate aminotransferase (mean difference: 6.4 U/L, 95% CI 3.0-9.7), compared to NAFLD-only. Similar results were obtained among the non-general population.

CONCLUSIONS

Metabolic dysfunction associated fatty liver disease and NAFLD are highly prevalent in the general population, with considerable overlap between them. However, compared to NAFLD, significantly more individuals were additionally identified by MAFLD than were missed. Importantly, by using the MAFLD criteria, more individuals with liver damage were identified. Therefore, the novel MAFLD definition is superior to NAFLD on a population level.

Impact of renaming NAFLD to MAFLD in an Australian regional cohort: Results from a prospective population-based study

BACKGROUND AND AIMS

Clinical and public health implications of the recent redefining of non-alcoholic fatty liver disease (NAFLD) to metabolic-associated fatty liver disease (MAFLD) remain unclear. We sought to determine the prevalence and compare MAFLD with NAFLD in a well-defined cohort.

METHODS

A cross-sectional study was conducted in regional Victoria with participants from randomly selected households. Demographic and health-related clinical and laboratory data were obtained. Fatty liver was defined as a fatty liver index ≥ 60 with MAFLD defined according to recent international expert consensus.

RESULTS

A total of 722 participants were included. Mean age was 59.3 ± 16 years, and 55.3% were women with a median body mass index of 27.8 kg/m² . Most (75.2%) participants were overweight or obese. MAFLD was present in 341 participants giving an unadjusted prevalence of 47.2% compared with a NAFLD prevalence of 38.7%. Fifty-nine (17.5%) participants met the criteria of MAFLD but not NAFLD. The increased prevalence of MAFLD in this cohort was primarily driven by dual etiology of fatty liver. All participants classified as NAFLD met the new definition of MAFLD. Compared with NAFLD subjects, participants with MAFLD had higher ALT (26.0 [14.0] U/L vs 30.0 [23] U/L, P = 0.024), but there were no differences in non-invasive markers for steatosis or fibrosis.

CONCLUSION

Metabolic-associated fatty liver disease is a highly prevalent condition within this large community cohort. Application of the MAFLD definition increased prevalence of fatty liver disease by including people with dual etiologies of liver disease.

Redefining non-alcoholic fatty liver disease to metabolic associated fatty liver disease: Is this plausible?

Recently, a single letter change has taken the world by storm. A group of experts have developed a consensus to upgrade the term non-alcoholic fatty liver disease (NAFLD) to metabolic associated fatty liver disease (MAFLD), suggesting that MAFLD would more accurately reflect not only the disease pathogenesis but would also help in patient stratification for management with NAFLD. However, the difference of opinion exists, which has made the NAFLD vs MAFLD debate the current talk of the town. This review will focus on the plausibility and implications of redefining NAFLD as MAFLD.

Fibrosis Burden of Missed and Added Populations According to the New Definition of Metabolic Dysfunction-Associated Fatty Liver

Recently, the classification of fatty liver and the definition for non-alcoholic fatty liver disease (NAFLD) have been challenged. Herein, we aim to evaluate the burden of hepatic fibrosis in the missed and added populations following the proposal of the new definition of metabolic dysfunction-associated fatty liver (MAFLD) in a health check-up cohort. A total of 6775 subjects underwent both magnetic resonance elastography (MRE) and an abdominal ultrasound at 13 nationwide health check-up centers in Korea. Significant and advanced hepatic fibrosis was defined as ≥3.0 kPa and ≥3.6 kPa in the MRE test, respectively. The prevalence of sonographic fatty liver (FL) was 47.4%. Among the subjects with sonographic FL, 77.3% and 94% are compatible with NAFLD and with the new MAFLD definitions, respectively. Moreover, 72% of FL cases belong to both the NAFLD and MAFLD definitions, whereas 1.4% is compatible with neither. The population compatible with the MAFLD definition has the following coexisting liver diseases: alcohol-related (71.9%), hepatitis B (23.9%), hepatitis C (0.4%), and both alcohol and viral hepatitis (2.8%). The prevalence of significant and advanced hepatic fibrosis is considerable in the MAFLD-only group. However, the prevalence of significant and advanced hepatic fibrosis is similar in the NAFLD-only group, and neither the NAFLD nor MAFLD group compared to healthy controls. The added population (MAFLD-only group), according to the new MAFLD definition, has a higher metabolic and fibrosis burden when compared to those in the missed population (NAFLD-only group).

The pathologic relevance of metabolic criteria in patients with biopsy-proven nonalcoholic fatty liver disease and metabolic dysfunction associated fatty liver disease: A multicenter cross-sectional study in China

BACKGROUND

This study aimed to assess the association between metabolic syndrome (MetS) and severity of nonalcoholic fatty liver disease (NAFLD), and to discuss the pathological relevance of the diagnostic criteria in metabolic (dysfunction) associated fatty liver disease (MAFLD).

METHODS

This was a multicenter, cross-sectional study. Patients with NAFLD confirmed by liver biopsy were enrolled between July 2016 and December 2018 from 14 centers across the mainland of China. Anthropometric and metabolic parameters were collected to assess the pathological relevance.

RESULTS

Of 246 enrolled patients with NAFLD, 150 (61.0%) had the comorbidity of MetS. With the increase of metabolic components, the proportions of nonalcoholic steatohepatitis (NASH) and significant fibrosis were notably increased. The comorbid three metabolic components significantly increased the proportion of NASH, and further increase of metabolic components did not increase the proportion of NASH. However, the increase of metabolic components was parallel to the increase of the proportion of liver fibrosis. Among the 246 patients, 239 (97.2%) met the diagnostic criteria of MAFLD. Although non-MAFLD patients had less NASH, they present with similar proportion of significant fibrosis and cirrhosis. In the diagnostic criteria of MAFLD, BMI ≥ 23 kg/m2 was related to NASH (Mantel-Haenszel Common Estimate OR: 2.975; 95% CI: 1.037-8.538; P = 0.043), and T2DM was related to significant fibrosis (Mantel-Haenszel Common Estimate OR: 2.531; 95% CI: 1.388-4.613; P = 0.002). The homeostasis model assessment of insulin resistance (HOMA-IR) ≥ 2.5 was the most significant factor for NASH (OR: 4.100; 95% CI: 1.772-9.487; P = 0.001) and significant factor for liver fibrosis (OR: 2.947; 95% CI: 1.398-6.210; P = 0.004) after the adjustments of the BMI and diabetes.

CONCLUSIONS

Metabolic dysregulations are important risk factors in NAFLD progression. The insulin resistance status may play a predominant role in the progression in MAFLD patients.

Editorial: an elastography-based two-step approach to detect NAFLD with compensated advanced chronic liver disease-authors' reply

This article is linked to Zhou et al and Wong papers. To view these articles, visit https://doi.org/10.1111/apt.16487 and https://doi.org/10.1111/apt.16507

MAFLD Criteria May Overlook a Subtype of Patient with Steatohepatitis and Significant Fibrosis

INTRODUCTION

Metabolic associated fatty liver disease (MAFLD) is a novel concept for fatty liver disease. Different from non-alcoholic fatty liver disease (NAFLD), the diagnosis of MAFLD requires the presence of metabolic risks. This study aimed to characterize patients with liver steatosis but without metabolic risks (non-MR-steatosis) which may not be diagnosed by MAFLD criteria.

METHODS

Consecutive patients who underwent biopsy were included in this study. The clinic-pathological characteristics of non-MR-steatosis, NAFLD and MAFLD were compared.

RESULTS

A total of 1217 cases were included. There were 426 (35.00%) cases with MAFLD, 585 (48.07%) with NAFLD and 168 (13.80%) with non-MR-steatosis. The majority of the cases were infected with HBV (93.26%). The age and metabolic profiles were highest in MAFLD and lowest in non-MR-steatosis. The body mass index (BMI) level was also lowest in non-MR-steatosis (20.78 ± 1.54 kg/m2). The ALT and AST levels of the non-MR-steatosis group were not statistically different from those of MAFLD or NAFLD groups (p > 0.05). Histologically, there was no significant difference in the degrees of inflammation and fibrosis among the three groups. The severity of steatosis in non-MR-steatosis group was lower than MAFLD or NAFLD groups (p < 0.05). These results were consistent in both HBV and non-HBV subgroups.

CONCLUSION

MAFLD criteria may overlook some steatotic patients without metabolic risks, who may also have steatohepatitis and significant fibrosis.

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.

From nonalcoholic fatty liver disease to metabolic-associated fatty liver disease: Big wave or ripple?

There is some dissatisfaction with the term "nonalcoholic fatty liver disease (NAFLD)," which overemphasizes alcohol and underemphasizes the importance of metabolic risk factors in this disease. Recently, a consensus recommended "metabolic (dysfunction)-associated fatty liver disease (MAFLD)" as a more appropriate term to describe fatty liver diseases (FLD) associated with metabolic dysfunction. During the definition change from NAFLD to MAFLD, subjects with FLD and metabolic abnormalities, together with other etiologies of liver diseases such as alcohol, virus, or medication who have been excluded from the NAFLD criteria, were added to the MAFLD criteria, while subjects with FLD but without metabolic abnormality, who have been included in the NAFLD criteria, were excluded from the MAFLD criteria. This means that there is an emphasis on the metabolic dysfunction in MAFLD which may underestimate the prognostic value of hepatic steatosis itself, whereas the MAFLD criteria might better identify subjects who are at a higher risk of hepatic or cardiovascular outcomes. However, non-metabolic risk NAFLD subjects who are excluded from the MAFLD criteria are missed from the diagnosis, and their potential risk can be the cause of future diseases. Although huge controversies remain, this review focused on summarizing recent studies that compared the clinical and prognostic characteristics between subjects with NAFLD and MAFLD.