Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD)-Rather a Bystander Than a Driver of Mortality

Lean non-alcoholic fatty liver disease and the risk of all-cause mortality: An updated meta-analysis

INTRODUCTION AND OBJECTIVES

Cohort studies reported controversial results regarding the long-term prognosis of patients with lean non-alcoholic fatty liver disease (NAFLD) compared to non-lean NAFLD patients. This updated meta-analysis aimed to estimate the magnitude of the association between lean body mass index and all-cause mortality risk in NAFLD patients.

MATERIALS AND METHODS

We systematically searched the EMBASE and MEDLINE databases from inception to March 2023 to identify observational studies that reported hazard ratio (HR) for all-cause mortality of patients with lean NAFLD versus those with non-lean, overweight, or obese NAFLD. Multivariable-adjusted hazard ratios (HRs) for all-cause mortality were pooled using a random effects model.

RESULTS

Fourteen studies with 94,181 NAFLD patients (11.3 % with lean NAFLD) and 7,443 fatal events over a median follow-up of 8.4 years (IQR, 6.6-17.4 years) were included. Patients with lean NAFLD had a higher risk of all-cause mortality than those with non-lean NAFLD (random-effects HR 1.61, 95 % CI 1.37-1.89; I2=77 %). The magnitude of this risk remained unchanged even after stratified analysis by measures of NAFLD diagnosis, study country, cohort setting, length of follow-up, adjustment with fibrosis stage/cirrhosis, and the Newcastle-Ottawa Scale. The risk was independent of age, sex, and cardiometabolic risk factors. Sensitivity analyses did not alter these findings. The funnel plot and Egger's test revealed no significant publication bias.

CONCLUSIONS

This meta-analysis revealed that lean NAFLD is associated with an approximately 1.6-fold increased mortality risk. Further studies are needed to unravel the existing but complex link between lean NAFLD and an increased risk of death.

Association of Stroke With Metabolic Dysfunction-Associated Fatty Liver Disease With and Without CKD

RATIONALE & OBJECTIVE

Metabolic dysfunction-associated fatty liver disease (MAFLD), a risk factor for stroke and all-cause mortality, is highly prevalent among patients with chronic kidney disease (CKD), but it is unclear whether the association of MAFLD with stroke and all-cause mortality differs within and outside of the setting of CKD.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

We enrolled 95,353 participants from the Kailuan Cohort Study, among whom 35,749 had CKD at baseline or developed CKD during the follow-up period, and 59,604 individuals who had no CKD at baseline or during the follow-up period.

EXPOSURE

MAFLD.

OUTCOME

Stroke (ischemic stroke, hemorrhagic stroke), all-cause mortality.

ANALYTICAL APPROACH

Adjusted Cox regression models were used to estimate the influence of MAFLD on stroke outcomes within the subgroups defined by the presence of CKD.

RESULTS

After a median follow-up of 12.8 years, 6,140 strokes (6.4%) and 11,975 deaths from any cause (12.6%) occurred. After adjusting for potential confounders, MAFLD was associated with an increased incidence of stroke among the participants with CKD (HR, 1.34 [95% CI, 1.23-1.45]) but not among those without CKD (HR, 1.05 [95% CI, 0.97-1.15]; Pinteraction<0.001). This association was principally related to ischemic stroke (HR, 1.38 [95% CI, 1.26-1.51]) and not hemorrhagic stroke (HR, 1.04 [95% CI, 0.85-1.26]). No association was found between MAFLD and all-cause mortality in the participants with CKD (HR,1.04 [95% CI, 0.98-1.10]) or those without CKD (HR,1.03 [95% CI, 0.97-1.09]). Among the participants with CKD, compared with non-MAFLD, MAFLD with diabetes (HR,1.36 [95% CI, 1.23-1.50]) or overweight/obesity (HR,1.30 [95% CI, 1.14-1.50]) was associated with a higher risk of stroke whereas MAFLD without overweight/obesity or diabetes was not associated with a higher risk (HR,1.08 [95% CI, 0.81-1.43]).

LIMITATIONS

This was an observational study and included individuals with CKD who had a relatively high estimated glomerular filtration rate.

CONCLUSIONS

MAFLD was associated with an increased risk of stroke in individuals with CKD but not in those without CKD.

PLAIN-LANGUAGE SUMMARY

Metabolic dysfunction-associated fatty liver disease (MAFLD), which is recognized as a risk factor for stroke in the general population, is highly prevalent among individuals with chronic kidney disease (CKD). However, the impact of MAFLD on the risk of stroke in patients with CKD remains uncertain. We investigated the association of MAFLD with stroke in individuals with and without CKD. Our analysis revealed that MAFLD was associated with a significantly increased risk of stroke in individuals with CKD, and the magnitude of this increased risk was greater in the setting of CKD. These findings highlight the need for increased attention to MAFLD in patients with CKD and emphasize that addressing and preventing MAFLD in this population may contribute to reduced morbidity from stroke.

Update in lean metabolic dysfunction-associated steatotic liver disease

BACKGROUND

A new nomenclature consensus has emerged for liver diseases that were previously known as non-alcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated fatty liver disease (MAFLD). They are now defined as metabolic dysfunction-associated steatotic liver disease (MASLD), which includes cardiometabolic criteria in adults. This condition, extensively studied in obese or overweight patients, constitutes around 30% of the population, with a steady increase worldwide. Lean patients account for approximately 10%-15% of the MASLD population. However, the pathogenesis is complex and is not well understood.

AIM

To systematically review the literature on the diagnosis, pathogenesis, characteristics, and prognosis in lean MASLD patients and provide an interpretation of these new criteria.

METHODS

We conducted a comprehensive database search on PubMed and Google Scholar between January 2012 and September 2023, specifically focusing on lean NAFLD, MAFLD, or MASLD patients. We include original articles with patients aged 18 years or older, with a lean body mass index categorized according to the World Health Organization criteria, using a cutoff of 25 kg/m2 for the general population and 23 kg/m2 for the Asian population.

RESULTS

We include 85 studies in our analysis. Our findings revealed that, for lean NAFLD patients, the prevalence rate varied widely, ranging from 3.8% to 34.1%. The precise pathogenesis mechanism remained elusive, with associations found in genetic variants, epigenetic modifications, and adaptative metabolic response. Common risk factors included metabolic syndrome, hypertension, and type 2 diabetes mellitus, but their prevalence varied based on the comparison group involving lean patients. Regarding non-invasive tools, Fibrosis-4 index outperformed the NAFLD fibrosis score in lean patients. Lifestyle modifications aided in reducing hepatic steatosis and improving cardiometabolic profiles, with some medications showing efficacy to a lesser extent. However, lean NAFLD patients exhibited a worse prognosis compared to the obese or overweight counterpart.

CONCLUSION

MASLD is a complex disease comprising epigenetic, genetic, and metabolic factors in its pathogenesis. Results vary across populations, gender, and age. Limited data exists on clinical practice guidelines for lean patients. Future studies employing this new nomenclature can contribute to standardizing and generalizing results among lean patients with steatotic liver disease.

Global epidemiology of type 2 diabetes in patients with NAFLD or MAFLD: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD) shares common pathophysiological mechanisms with type 2 diabetes, making them significant risk factors for type 2 diabetes. The present study aimed to assess the epidemiological feature of type 2 diabetes in patients with NAFLD or MAFLD at global levels.

METHODS

Published studies were searched for terms that included type 2 diabetes, and NAFLD or MAFLD using PubMed, EMBASE, MEDLINE, and Web of Science databases from their inception to December 2022. The pooled global and regional prevalence and incidence density of type 2 diabetes in patients with NAFLD or MAFLD were evaluated using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

RESULTS

A total of 395 studies (6,878,568 participants with NAFLD; 1,172,637 participants with MAFLD) from 40 countries or areas were included in the meta-analysis. The pooled prevalence of type 2 diabetes among NAFLD or MAFLD patients was 28.3% (95% confidence interval 25.2-31.6%) and 26.2% (23.9-28.6%) globally. The incidence density of type 2 diabetes in NAFLD or MAFLD patients was 24.6 per 1000-person year (20.7 to 29.2) and 26.9 per 1000-person year (7.3 to 44.4), respectively.

CONCLUSIONS

The present study describes the global prevalence and incidence of type 2 diabetes in patients with NAFLD or MAFLD. The study findings serve as a valuable resource to assess the global clinical and economic impact of type 2 diabetes in patients with NAFLD or MAFLD.

Development and Internal Validation of a Model for Predicting Overall Survival in Subjects with MAFLD: A Cohort Study

Background & Aims: Fatty liver disease with metabolic dysfunction (MAFLD) is a new concept proposed to replace the previous concept of Non-Alcoholic Hepatic Steatosis (NAFLD). We developed and internally validated a prognostic model to predict the likelihood of death in a cohort of subjects with MAFLD. Methods: Our work involved two steps: the first was the construction of a bootstrapped multivariable Cox model for mortality risk prognosis and the second was its validation. Results: The study cohort included 1506 subjects, of which 907 were used for internal validation. Discriminant measures for the final model were R2D 0.6845 and Harrell's C 0.8422 in the development and R2D 0.6930 and Harrell's C 0.8465 in the validation. We used the nine independent prognostic factors selected by the LASSO Cox procedure and fitted by the bootstrap Cox survival model, and observed β were: Gender 0.356 1.42 (p < 0.008), Age 0.146 (p < 0.001), Glycemia 0.004 (p < 0.002), Total Cholesterol -0.0040 (p < 0.009), Gamma Glutamyl Transpeptidase 0.009 (p < 0.001), SBP 0.009 (p < 0.036), DBP -0.016 (p < 0.041), ALP 0.008 (p < 0.071) and Widowhood 0.550 (p < 0.001). Conclusions: We produced and validated a model to estimate the probability of death in subjects with MAFLD. The instruments we used showed satisfactory predictive capabilities.

Metabolic associated fatty liver disease and sarcopenia additively increase mortality: a real-world study

BACKGROUND AND AIMS

Sarcopenia is associated with worse prognosis for non-alcoholic fatty liver disease (NAFLD). However, disease progression in the MAFLD-related sarcopenia is largely unknown. We aimed to clarify the relationship between MAFLD and/or sarcopenia with mortality and liver fibrosis in the real world.

METHODS

A total of 13,692 individuals were selected from the third National Health and Nutrition Examination Surveys and linked mortality until December 2019. MAFLD is diagnosed based on a radiologically diagnosed hepatic steatosis and the presence of any one of the following three conditions: overweight/obesity, diabetes mellitus (DM), or metabolic dysregulation. Sarcopenia is defined by weight-adjusted skeletal muscle mass.

RESULTS

The mean age was 43.7 ± 15.97 years, and 47.3% of the individuals were male. MAFLD was diagnosed in 4207/13,692 (30.73%) participants, and the proportion of sarcopenic was 19.42% amongst subjects with MAFLD. The mean follow-up duration was of 23.7 ± 7.62 years. MAFLD (aHR 1.152, 95% CI 1.070-1.241) and sarcopenia (aHR 1.123, 95% CI 1.042-1.210) were related to increased all-cause mortality in MAFLD after adjustment for age, sex, race, marital status, education, and smoking. Stratified analysis revealed that MAFLD and sarcopenia additively increased the risk of mortality (aHR 1.247, 95% CI 1.132-1.373) and liver fibrosis (aOR 2.296, 95% CI 1.718-3.069 assessed by NFS score >0.676; aOR 2.218, 95% CI 1.788-2.752 assessed by FIB-4 score >1.3) in fully adjusted models (P < 0.001 for all).

CONCLUSION

Sarcopenia in individuals with MAFLD portends increased mortality and significant liver fibrosis. Novel therapeutic strategies targeting at increasing skeletal muscle mass should be explored for patients with MAFLD.

Insulin resistance and central obesity determine hepatic steatosis and explain cardiovascular risk in steatotic liver disease

Background

Metabolic dysfunction-associated steatotic liver disease (MASLD) has recently been proposed to replace non-alcoholic fatty liver disease and focus on patients with progressive disease due to the presence of metabolic dysfunction. However, it is unclear whether the new definition actually identifies patients with hepatic steatosis at increased cardiovascular risk.

Methods

A total of 4,286 asymptomatic subjects from the SAKKOPI study aged 45-80 years undergoing screening colonoscopy were analyzed. Steatosis was diagnosed by abdominal ultrasound. MASLD was diagnosed according to the recent expert consensus. Insulin resistance was assessed by homeostasis model assessment-insulin resistance score (HOMA-IR) (cutoff: ≥2.5), subclinical inflammation was estimated by ferritin/CRP/uric acid, and cardiovascular risk was assessed using SCORE2/ASCVD.

Results

Mean age was 59.4 ± 8.5 years, 51.6% were male; mean BMI was 27.0 ± 4.5 kg/m², 9.2% had type 2 diabetes mellitus. In total, 1,903 (44.4%) were diagnosed with hepatic steatosis and were characterized by more severe metabolic dysfunction including insulin resistance (47.1% vs. 12.2%, p < 0.001) and central obesity (waist circumference ≥102/88 cm, 71.8% vs. 37.1%, p < 0.001). This translated into higher (subclinical) inflammation (ferritin 153 vs. 95 mg/dL, p < 0.001, uric acid 6.3 mg/dL vs. 5.2 mg/dL, p < 0.001) and 10-year cardiovascular risk (SCORE2 7.8 points vs. 5.1 points, p < 0.001, ASCVD 17.9 points vs. 10.8 points, p < 0.001). 99.0% of subjects with steatosis met the MASLD definition, 95.4% met the MAFLD definition, and 53.6% met the definition of metabolic syndrome, while 95.4% of subjects without steatosis also met the MASLD criteria for metabolic dysfunction compared to 69.0% and 17.4% who met the MAFLD and metabolic syndrome criteria, respectively. Forward stepwise regression indicated that waist circumference, HOMA-IR, and triglycerides were most relevant in explaining the presence of hepatic steatosis across all subgroups of increasing metabolic dysfunction. At the same time, hepatic steatosis was not associated with cardiovascular risk in the overall cohort (SCORE2: B = 0.060, 95% CI: -0.193-0.314, and p = 0.642) and in patients with metabolic dysfunction after adjusting for age, sex, and these three metabolic dysfunction components.

Conclusion

Although hepatic steatosis is associated with increased central obesity and insulin resistance, metabolic dysfunction per se rather than hepatic steatosis explains cardiovascular risk in these patients.

Mortality and Liver-Related Events in Lean Versus Non-Lean Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Although approximately 40% of patients with nonalcoholic fatty liver disease (NAFLD) are nonobese or lean, little is known about the long-term clinical outcomes of lean NAFLD. We aimed to estimate the risk of mortality and adverse liver-related events in patients with lean NAFLD compared with those with non-lean NAFLD.

METHODS

We searched the PubMed, Embase, and Cochrane Library databases through May 2022 for articles reporting mortality and/or development of cirrhosis among lean and non-lean NAFLD patients. The relative risks (RRs) of all-cause mortality, cardiovascular mortality, liver-related mortality, and occurrence of decompensated cirrhosis or hepatocellular carcinoma were pooled using the random-effects model. We also performed subgroup analysis according to characteristics of the study population, methods of NAFLD diagnosis, study design, study region, and length of follow-up.

RESULTS

We analyzed 10 cohort studies involving 109,151 NAFLD patients. Patients with lean NAFLD had comparable risks for all-cause mortality (RR, 1.09; 95% confidence interval [CI], 0.66-1.90), cardiovascular mortality (RR, 1.12; 95% CI, 0.66-1.90), and adverse liver events including decompensated cirrhosis and hepatocellular carcinoma (RR, 0.81; 95% CI, 0.50-1.30). However, the risk of liver-related mortality was higher in patients with lean than non-lean NAFLD (RR, 1.88; 95% CI, 1.02-3.45).

CONCLUSIONS

This study highlights a higher risk of liver-related mortality in patients with lean NAFLD than those with non-lean NAFLD. This finding indicates that further understanding of the pathophysiology, risk factors of adverse outcomes, and genetic and ethnic variabilities of lean NAFLD phenotype is warranted for individualized treatment strategies in lean NAFLD patients.

Lean Metabolic-Associated Fatty Liver Disease

Since the nomenclature change from nonalcoholic fatty liver disease (NAFLD) to metabolic-associated fatty liver disease (MAFLD), much work has been undertaken to establish the clinical characteristics as well as the hepatic and extrahepatic complications of the different MAFLD subtypes. Currently, there has been significant work performed to evaluate previously acknowledged evidence in the lean NAFLD population to determine its applicability to the new entity. This article examines recently published data on lean MAFLD cohorts to highlight the prevalence, pathophysiological characteristics, associated liver fibrosis, genetics, hepatic and extrahepatic complications, prognosis, treatment, and research into this unique subtype of MAFLD.

Focus on Liver Function Abnormalities in Patients With Turner Syndrome: Risk Factors and Evaluation of Fibrosis Risk

CONTEXT

Liver function abnormalities (LFAs) have been described in patients with Turner syndrome (TS). Although a high risk of cirrhosis has been reported, there is a need to assess the severity of liver damage in a large cohort of adult patients with TS.

OBJECTIVE

Evaluate the types of LFAs and their respective prevalence, search for their risk factors, and evaluate the severity of liver impairment by using a noninvasive fibrosis marker.

METHODS

This was a monocentric retrospective cross-sectional study. Data were collected during a day hospital visit. The main outcome measures were liver enzymes (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase), FIB-4 score, liver ultrasound imaging, elastography, and liver biopsies, when available.

RESULTS

264 patients with TS were evaluated at a mean age of 31.15 ± 11.48 years. The overall prevalence of LFAs was 42.8%. The risk factors were age, body mass index, insulin resistance, and an X isochromosome (Xq). The mean FIB-4 sore of the entire cohort was 0.67 ± 0.41. Less than 10% of patients were at risk of developing fibrosis. Cirrhosis was observed in 2/19 liver biopsies. There was no significant difference in the prevalence of LFAs between premenopausal patients with natural cycles and those receiving hormone replacement therapy (P = .063). A multivariate analysis adjusted for age showed no statistically significant correlation between hormone replacement therapy and abnormal gamma-glutamyl transferase levels (P = .12).

CONCLUSION

Patients with TS have a high prevalence of LFA. However, 10% are at high risk of developing fibrosis. The FIB-4 score is useful and should be part of the routine screening strategy. Longitudinal studies and better interactions with hepatologists should improve our knowledge of liver disease in patients with TS.

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.

Trends in prevalence and all-cause mortality of metabolic dysfunction-associated fatty liver disease among adults in the past three decades: Results from the NHANES study

BACKGROUND

Given the escalating epidemic of obesity and diabetes coupled with redefined diagnostic criteria, it is critical to identify the prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD). We sought to determine the prevalence and mortality outcomes of MAFLD subtypes based on diagnostic criteria in the USA over the past three decades.

METHODS

Eleven cycles of the National Health and Nutrition Examination Surveys (NHANES; 1988-1994 and 1999-2020) were used, and 72,224 participants were included. MAFLD was defined according to the 2020 International Expert Consensus. Based on diagnostic criteria and risk factors, MAFLD was categorized into seven subtypes: type 1 (obesity subtype), 2 (metabolic unhealthy subtype), 3 (diabetes subtype), 4 (metabolic unhealthy non-diabetes subtype), 5 (obesity and diabetes subtype), 6 (metabolic unhealthy non-obesity subtype), and 7 (mixed subtype).

RESULTS

Over the study period, the estimated prevalence of MAFLD increased significantly from 22% in 1988-1994 to 36% in 2017-2020. The prevalence of Type 4 was the highest, followed by that of Type 7, whereas other types were low and almost unchanged over time. Individuals with MAFLD had 19% and 38% increased mortality risks from all causes and cardiovascular disease, respectively. Among them, the metabolically unhealthy participants with normal weight demonstrated a 116% higher risk for all-cause mortality [hazard ratio (HR): 2.16, 95% CI: 1.52-3.08] and a 222% higher risk for cardiovascular mortality (HR: 3.22, 95% CI: 1.72-6.04). Interestingly, stratification and interaction analyses demonstrated a significant impact of metabolic parameters on the relationship between MAFLD and all-cause mortality.

CONCLUSIONS

In conclusion, our study identified an increase in MAFLD prevalence and a significant association between metabolic derangements in MAFLD and all-cause or cardiovascular mortality.

An Observational Data Meta-analysis on the Differences in Prevalence and Risk Factors Between MAFLD vs NAFLD

BACKGROUND & AIMS

The shift to redefine nonalcoholic fatty liver disease (NAFLD) as metabolic associated fatty liver disease (MAFLD) can profoundly affect patient care, health care professionals, and progress within the field. To date, there remains no consensus on the characterization of NAFLD vs MAFLD. Thus, this study sought to compare the differences between the natural history of NAFLD and MAFLD.

METHODS

Medline and Embase databases were searched to include articles on prevalence, risk factors, or outcomes of patients with MAFLD or NAFLD. Meta-analysis of proportions was conducted using the generalized linear mix model. Risk factors and outcomes were evaluated in conventional pairwise meta-analysis.

RESULTS

Twenty-two articles involving 379,801 patients were included. Pooled prevalence of MAFLD was 39.22% (95% confidence interval [CI], 30.96%-48.15%) with the highest prevalence in Europe and Asia, followed by North America. The current MAFLD Definition only accounted for 81.59% (95% CI, 66.51%-90.82%) of NAFLD diagnoses. Patients had increased odds of being diagnosed with MAFLD compared with NAFLD (odds ratio, 1.37; 95% CI, 1.16-1.63; P < .001). Imaging modality resulted in a significantly higher odds of being diagnosed with MAFLD compared with NAFLD, but not biopsy. MAFLD was significantly associated with males, higher body mass index, hypertension, diabetes, lipids, transaminitis, and greater fibrosis scores compared with NAFLD.

CONCLUSIONS

There were stark differences in the prevalence and risk factors between MAFLD and NAFLD. However, in the use of the MAFLD Definition, a greater emphasis on the management of concomitant metabolic diseases and a collaborative effort is required to explore the complex pathophysiologic mechanisms underlying the disease.

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.

MAFLD and NAFLD in the prediction of incident chronic kidney disease

Whether metabolic dysfunction-associated fatty liver disease (MAFLD) can replace nonalcoholic fatty liver disease (NAFLD) is under debate. This study evaluated which definition better predicted incident chronic kidney disease (CKD). This was a 5.3-year (range, 2.8-8.3) retrospective cohort study of 21,713 adults who underwent at least two serial health examinations. Cox analyses were used to compare the risk of incident CKD among non-fatty liver disease (FLD) without metabolic dysregulation (MD; reference), non-FLD with MD, MAFLD-only, NAFLD-only, or both-FLD groups. Non-FLD with MD group (hazard ratio [HR] 1.23, 95% confidence interval [CI] 1.00-1.53), both-FLD group (HR 1.50, 95% CI 1.19-1.89), and MAFLD-only group (HR 1.97, 95% CI 1.49-2.60), but not NAFLD-only group (HR 1.06, 95% CI 0.63-1.79) demonstrated an increased risk of CKD. The increased risk of CKD was significant in MAFLD subgroups with overweight/obesity (HR 2.94, 95% CI 1.91-4.55), diabetes (HR 2.20, 95% CI 1.67-2.90), MD only (HR 1.50, 95% CI 1.19-1.89), excessive alcohol consumption (HR 2.71, 95% CI 2.11-3.47), and viral hepatitis (HR 2.38, 95% CI 1.48-3.84). The switch from NAFLD to MAFLD criteria may identify a greater number of individuals at CKD risk. The association was also significant in MAFLD patients with excessive alcohol consumption or viral hepatitis.

Cardiometabolic characterization in metabolic dysfunction–associated fatty liver disease

Background

To better understand the patient's heterogeneity in fatty liver disease (FLD), metabolic dysfunction–associated fatty liver disease (MAFLD) was proposed by international experts as a new nomenclature for nonalcoholic fatty liver disease (NAFLD). We aimed to evaluate the cardiovascular risk, assessed through coronary artery calcium (CAC) and epicardial adipose tissue (EAT), of patients without FLD and patients with FLD and its different subtypes.

Methods

Cross sectional study of 370 patients. Patients with FLD were divided into 4 groups: FLD without metabolic dysfunction (non-MD FLD), MAFLD and the presence of overweight/obesity (MAFLD-OW), MAFLD and the presence of two metabolic abnormalities (MAFLD-MD) and MAFLD and the presence of T2D (MAFLD-T2D). MAFLD-OW included two subgroups: metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUHO). The patients without FLD were divided into 2 groups: patients without FLD and without MD (non-FLD nor MD; reference group) and patients without FLD but with MD (non-FLD with MD). EAT and CAC (measured through the Agatston Score) were determined by computed tomography.

Results

Compared with the reference group (non-FLD nor MD), regarding EAT, patients with MAFLD-T2D and MAFLD-MUHO had the highest risk for CVD (OR 15.87, 95% CI 4.26-59.12 and OR 17.60, 95% CI 6.71-46.20, respectively), patients with MAFLD-MHO were also at risk for CVD (OR 3.62, 95% CI 1.83-7.16), and patients with non-MD FLD did not have a significantly increased risk (OR 1.77; 95% CI 0.67-4.73). Regarding CAC, patients with MAFLD-T2D had an increased risk for CVD (OR 6.56, 95% CI 2.18-19.76). Patients with MAFLD-MUHO, MAFLD-MHO and non-MD FLD did not have a significantly increased risk compared with the reference group (OR 2.54, 95% CI 0.90-7.13; OR 1.84, 95% CI 0.67-5.00 and OR 2.11, 95% CI 0.46-9.74, respectively).

Conclusion

MAFLD–T2D and MAFLD–OW phenotypes had a significant risk for CVD. MAFLD new criteria reinforced the importance of identifying metabolic phenotypes in populations as it may help to identify patients with higher CVD risk and offer a personalized therapeutic management in a primary prevention setting.

Global Prevalence and Clinical Characteristics of Metabolic-associated Fatty Liver Disease: A Meta-Analysis and Systematic Review of 10 739 607 Individuals

BACKGROUND AND AIMS

Metabolic-associated fatty liver disease (MAFLD) was proposed as a better definition of nonalcoholic fatty liver disease (NAFLD) to encompass the metabolic dysregulation associated with NAFLD. This redefinition challenges our understanding of the disease. Hence, this study sought to conduct an updated analysis of the prevalence, clinical characteristics, and associated factors of MAFLD, with a further sensitivity analysis done based on lean and nonobese MAFLD individuals.

METHODS

Medline and Embase databases were searched to include articles on MAFLD. Meta-analysis of proportions was conducted using the generalized linear mix model. Associating factors were evaluated in conventional pairwise meta-analysis with sensitivity analysis on lean and nonobese MAFLD.

RESULTS

From pooled analysis involving 3 320 108 individuals, the overall prevalence of MAFLD was 38.77% (95% CI 32.94% to 44.95%); 5.37% (95% CI 4.36% to 6.59%) and 29.78% (95% CI 26.06% to 33.79%) of lean and nonobese individuals, respectively, had MAFLD. Metabolic complications such as hypertension [odds ratio (OR) 2.63, 95% CI 1.85 to 3.74, P < 0.0001 and OR 2.03; 95% CI 1.74 to 2.38, P < 0.0001, respectively] and diabetes (OR 3.80, 95% CI 2.65 to 5.43, P < 0.0001 and OR 3.46, 95% CI 2.81 to 4.27, P < 0.0001, respectively) were found as significant associating factors associated with lean and nonobese MAFLD.

CONCLUSIONS

This meta-analysis supports previous studies in reporting MAFLD to affect more than a third of the global population. While exploration of the pathogenic basis of fatty liver disease without metabolic dysregulation is required, the emphasis on management of concomitant metabolic disease in MAFLD can improve multidisciplinary efforts in managing the complex disease.

A new risk stratification strategy for fatty liver disease by incorporating MAFLD and fibrosis score in a large US population

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a newly proposed definition of fatty liver disease (FLD) independent of excessive alcohol consumption (EAC) and hepatitis viral infection. Evidence on the mortality risk in different types of FLD [nonalcoholic FLD (NAFLD), alcoholic FLD (AFLD), and MAFLD] is sparse, hindering the identification of high-risk populations for preferential clinical surveillance.

METHODS

A total of 11,000 participants in the Third National Health and Nutrition Examination Survey were enrolled. Participants were categorized into three groups [FLD( - ), MAFLD( - ), and MAFLD( +)] according to FLD and MAFLD criteria, and further categorized into six groups by EAC. Multivariate Cox proportional hazard model was used to estimate the risk of all-cause, cardiovascular-related, and cancer-related mortality.

RESULTS

During a median follow-up of 23.2 years, a total of 3240 deaths were identified. Compared with FLD( - )/EAC( - ) participants, MAFLD( +) individuals had higher all-cause mortality risk [hazard ratio (HR) = 1.28, 95% confidence interval (CI) = 1.18-1.39] regardless of EAC status [MAFLD( +)/NAFLD: HR = 1.22, 95%CI = 1.11-1.34; MAFLD( +)/AFLD: HR = 1.83, 95%CI = 1.46-2.28], while not for MAFLD( - ) individuals. Furthermore, diabetes-driven-MAFLD had higher mortality risk (HR = 2.00, 95%CI = 1.77-2.27) followed by metabolic dysregulation-driven-MAFLD (HR = 1.30, 95%CI = 1.06-1.60) and overweight/obesity-driven-MAFLD (HR = 1.11, 95%CI = 1.00-1.22). Additionally, MAFLD( - ) participants with elevated fibrosis score were also associated with statistically significantly higher mortality risk (HR = 3.23, 95%CI = 1.63-6.40).

CONCLUSIONS

Utilizing a representative sample of the US population, we proved the validity of MAFLD subtype and fibrosis score, rather than the traditional definition (NAFLD and AFLD), in the risk stratification of FLD patients. These findings may be applied to guide the determination of surveillance options for FLD patients.

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.

Metabolic Dysfunction-associated Fatty Liver Disease and Mortality Among Chinese Adults: a Prospective Cohort Study

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) was renamed metabolic dysfunction associated with fatty liver disease (MAFLD) recently.

OBJECTIVE

We aimed to explore the risk of all-cause deaths in MAFLD participants and compare it with NAFLD in Chinese adults.

METHODS

We enrolled 152 139 participants with abdominal ultrasonography in the Kailuan Cohort from 2006 to 2012. We categorized the participants into MAFLD and non-MAFLD, NAFLD and non-NAFLD, and 4 groups of Neither FLD, MAFLD only, NAFLD only, and MAFLD-NAFLD, respectively. We used Cox regression models to estimate the hazard ratios (HRs) and 95% CI of death.

RESULTS

The prevalence of MAFLD and NAFLD was 31.5% and 27.3%, respectively. After a median follow-up of 12.7 years, MAFLD and NAFLD both were associated with increased mortality, especially in men younger than 40 years, with HR (95% CI) of 1.51 (1.19-1.93) and 1.37 (1.06-1.78), respectively. The MAFLD-only group had higher mortality than the NAFLD-only in males 60 years or older (adjusted HR = 1.43; 95% CI, 1.00-2.03) and lower risk in males aged 40 to 59 years (adjusted HR = 0.65; 95% CI, 0.48-0.90). MAFLD with overweight/obesity-only decreased, but those with diabetes and/or metabolic dysregulation increased the risk of death. MAFLD with positive hepatitis B surface antigen and/or excessive alcohol consumption further increased the risk of death, especially in men younger than 40 years (HR = 9.86; 95% CI, 2.44-39.98).

CONCLUSION

MAFLD was associated with increased all-cause mortality among the Chinese population, which was different according to the status of overweight/obesity, diabetes, other metabolic indicators, and second causes. MAFLD patients should be managed by metabolic indicators and second causes to fulfill precise treatment and management.

MAFLD: what 2 years of the redefinition of fatty liver disease has taught us

Metabolic dysfunction-associated fatty liver disease (MAFLD) has appeared as the leading liver disease worldwide. Whereas the terminology nonalcoholic fatty liver disease (NAFLD) mainly reflected a negative selection and exclusion of alcohol-related liver disease (ALD), the new definition made its focus on the association of MAFLD with overweight/obesity, type 2 diabetes and metabolic risk factors especially also in normal weight/lean subjects. Several studies from the past 2 years have now used the new definition and have provided substantial information that this new definition might be accurate. Studies from the past 2 years have provided evidence that the new definition might be especially advantageous in the characterization and identification of patients with significant fibrosis. This has also been demonstrated in the well-known Rotterdam study in which the MAFLD-only group showed a higher rate of fibrosis and liver stiffness. MAFLD might also be able to predict all-cause mortality as demonstrated in the Third National Health and Nutrition Examination Survey. Furthermore, MAFLD might improve characterization of the cardiovascular risk of this patient population. As the term MAFLD has not yet been accepted universally, it remains important to coordinate efforts globally to adapt to this new definition and especially involve all specialities dealing with metabolic disorders such as diabetologists to further improve its definition and to prepare the medical community for its future use. The aim of this review is to summarize and critically address evidence emerging over the past 2 years that usage of the term MAFLD could be helpful in daily clinical practice.

Association of MAFLD With Diabetes, Chronic Kidney Disease, and Cardiovascular Disease: A 4.6-Year Cohort Study in China

CONTEXT

In 2020, the terminology of metabolic dysfunction-associated fatty liver disease (MAFLD) was proposed to replace nonalcoholic fatty liver disease (NAFLD).

OBJECTIVES

This work aimed to investigate the prevalence and incidence of MAFLD and evaluate its effects on incident extrahepatic diseases.

METHODS

A total of 6873 individuals, with a 4.6-year follow-up, were included in this study. Associations of MAFLD and NAFLD with diabetes, chronic kidney disease (CKD), and cardiovascular disease (CVD) were examined using logistic regression and Cox proportional hazards models.

RESULTS

The prevalence of NAFLD and MAFLD was 40.3% (95% CI, 39.2%-41.5%) and 46.7% (95% CI, 45.6%-47.9%), respectively. Additionally, 321 (4.7%) and 156 (2.3%) participants had MAFLD with excessive alcohol consumption and hepatitis B virus (HBV) infection. During the follow-up period, the incidence of NAFLD and MAFLD was 22.7% (95% CI, 21.3%-24.0%) and 27.0% (95% CI, 25.5%-28.4%). MAFLD was associated with higher risks of incident diabetes (risk ratio [RR] 2.08; 95% CI, 1.72-2.52), CKD (RR 1.64; 95% CI, 1.39-1.94), and CVD (hazard ratio 1.44; 95% CI, 1.15-1.81). Similar associations for NAFLD were observed. Furthermore, the MAFLD subgroups with excessive alcohol consumption (RR 2.49; 95% CI, 1.64-3.78) and HBV infection (RR 1.98; 95% CI, 1.11-3.52) were associated with higher risks of incident diabetes.

CONCLUSION

The change from NAFLD to MAFLD did not greatly affect the associations with diabetes, CKD, and CVD. MAFLD further identified those patients of metabolically fatty liver combined with excessive alcohol consumption and HBV infection, who had increased risks of incident diabetes compared with those of non-fatty liver.

Metabolic dysfunction-associated fatty liver disease and cardiovascular disease: A meta-analysis

BACKGROUND

Metabolic dysfunction-associated fatty liver disease [MAFLD, formerly known as nonalcoholic fatty liver disease (NAFLD)] is one of the most important causes of liver disease worldwide, while cardiovascular disease (CVD) is still one of the main causes of morbidity and mortality worldwide, and the two are closely related. This study aimed to investigate the risk of CVD incidence or CVD-related mortality (CVD mortality) in patients diagnosed with MAFLD under new concepts and new diagnostic criteria.

METHODS

We searched English databases PubMed, Web of Science, Embase, and Cochrane Library for relevant literature. The language was restricted to English.

RESULTS

By 22 January 2022, 556 published studies were obtained through preliminary retrieval, and 10 cohort studies were included in this study. All statistical analyses were performed using Review Manager 5.2 software. Compared with the control group, patients in the MAFLD group had a significantly higher relative risk of CVD incidence or CVD mortality during the follow-up, with an RR rate of 1.95 (95% CI 1.76-2.17, p < 0.01). The incidence of CVD in the MAFLD group was more than twice that in the control group (RR 2.26, 95% CI 2.00-2.54, p < 0.01). The mortality rate of CVD was 1.57 times higher than that in the control group (RR 1.57, 95% CI 1.42-1.72, p < 0.01).

CONCLUSIONS

Patients diagnosed with MAFLD alone had higher cardiovascular mortality than those diagnosed with NAFLD alone based on the available data.

MAFLD Enhances Clinical Practice for Liver Disease in the Asia-Pacific region

Fatty liver is now a major cause of liver disease in the Asia-Pacific region. Liver diseases in this region have distinctive characteristics. First, fatty liver is frequently observed in lean/normal-weight individuals. However, there is no standard definition of this unique phenotype. Second, fatty liver is often observed in patients with concomitant viral hepatitis. The exclusion of viral hepatitis from non-alcoholic fatty liver disease limits its value and detracts from the investigation and holistic management of coexisting fatty liver in patients with viral hepatitis. Third, fatty liver-associated hepatocellular carcinoma (HCC) is generally categorized as non-B non-C HCC. Fourth, the population is aging rapidly, and it is imperative to develop a practicable, low-intensity exercise program for elderly patients. Fifth, most patients and non-specialized healthcare professionals still lack an awareness of the significance of fatty liver both in terms of intrahepatic and extrahepatic disease and cancer. Recently, an international expert panel proposed a new definition of fatty liver: metabolic dysfunction-associated fatty liver disease (MAFLD). One feature of MAFLD is that metabolic dysfunction is a prerequisite for diagnosis. Pertinent to regional issues, MAFLD also provides its diagnostic criteria in lean/normal-weight individuals. Furthermore, MAFLD is independent of any concomitant liver disease, including viral hepatitis. Therefore, MAFLD may be a more suitable definition for fatty liver in the Asia-Pacific region. In this review, we introduce the regional characteristics of fatty liver and discuss the advantages of MAFLD for improving clinical practice for liver disease in the region.

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.