Breaking new ground: MASLD vs. MAFLD-which holds the key for risk stratification?

Non-invasive Scores and Serum Biomarkers for Fatty Liver in the Era of Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD): A Comprehensive Review From NAFLD to MAFLD and MASLD

PURPOSE OF REVIEW

The prevalence of non-alcoholic fatty liver disease (NAFLD) is rapidly increasing worldwide, making it the leading cause of liver related morbidity and mortality. Currently, liver biopsy is the gold standard for assessing individuals with steatohepatitis and fibrosis. However, its invasiveness, sampling variability, and impracticality for large-scale screening has driven the search for non-invasive methods for early diagnosis and staging. In this review, we comprehensively summarise the evidence on the diagnostic performance and limitations of existing non-invasive serum biomarkers and scores in the diagnosis and evaluation of steatosis, steatohepatitis, and fibrosis.

RECENT FINDINGS

Several non-invasive serum biomarkers and scores have been developed over the last decade, although none has successfully been able to replace liver biopsy. The introduction of new NAFLD terminology, namely metabolic dysfunction-associated fatty liver disease (MAFLD) and more recently metabolic dysfunction-associated steatotic liver disease (MASLD), has initiated a debate on the interchangeability of these terminologies. Indeed, there is a need for more research on the variability of the performance of non-invasive serum biomarkers and scores across the diagnostic entities of NAFLD, MAFLD and MASLD. There remains a significant need for finding valid and reliable non-invasive methods for early diagnosis and assessment of steatohepatitis and fibrosis to facilitate prompt risk stratification and management to prevent disease progression and complications. Further exploration of the landscape of MASLD under the newly defined disease subtypes is warranted, with the need for more robust evidence to support the use of commonly used serum scores against the new MASLD criteria and validation of previously developed scores.

Clinical features and mortality outcomes of patients with MASLD only compared to those with MAFLD and MASLD

BACKGROUND AND AIMS

The applicability of the proposed metabolic dysfunction-associated steatotic liver disease (MASLD) definition has not been validated. We aimed to characterize the profiles and long-term survival of people meeting the criteria for MASLD, but not that of metabolic dysfunction-associated fatty liver disease (MAFLD), i.e. MASLD only.

METHODS

Using data from the Third National Health and Nutrition Examination Survey (NHANES III) 1988-1994, 7791 adult participants were included and categorized into four distinct groups: no SLD, non-MAFLD MASLD, MASLD-MAFLD, and cryptogenic SLD (steatosis without metabolic dysfunction).

RESULTS

Participants in the MASLD-only group were younger and had better metabolic profiles and fibrosis degree compared to those with MASLD-MAFLD and those with no SLD. Their profiles were comparable to those with cryptogenic SLD. Similarly, the MASLD-only group tend to have lower cumulative incidence of all-cause and cardiovascular mortality. Clustering analysis showed that MASLD only clusters differently from individuals with MASLD-MAFLD.

CONCLUSIONS

MASLD only is a distinct clinical group with substantial heterogeneity compared to those captured using the MAFLD criteria.

Liver diseases and hepatocellular carcinoma in the Asia-Pacific region: burden, trends, challenges and future directions

Globally, nearly half of deaths from cirrhosis and chronic liver diseases (CLD) and three-quarters of deaths from hepatocellular carcinoma (HCC) occur in the Asia-Pacific region. Chronic hepatitis B is responsible for the vast majority of liver-related deaths in the region. Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common form of CLD, affecting an estimated 30% of the adult population. Compared with people of European descent, people from the Asia-Pacific region carry more genetic variants associated with MASLD and its progression. Alcohol is a fast-growing cause of CLD and HCC in Asia as a result of the rising per-capita consumption of alcohol. Drug-induced liver injury is under-recognized and probably has a high prevalence in this region. The epidemiological and outcome data of acute-on-chronic liver failure are heterogeneous, and non-unified definitions across regions contribute to this heterogeneity. CLDs are severely underdiagnosed, and effective treatments and vaccinations are underutilized. In this Review, we highlight trends in the burden of CLD and HCC in the Asia-Pacific region and discuss the rapidly changing aetiologies of liver disease. We examine the multiple gaps in the care cascade and propose mitigating strategies and future directions.

Letter: MAFLD versus MASLD-The devil lies in the details

This article is linked to Kim et al paper. To view this article, visit https://doi.org/10.1111/apt.18011

MAFLD predicts cardiovascular disease risk better than MASLD

BACKGROUND AND AIM

Metabolic dysfunction-associated steatotic liver disease (MASLD) has been proposed as an alternative for the validated definition of metabolic dysfunction-associated fatty liver disease (MAFLD). We compared the abilities of MAFLD and MASLD to predict the risk of atherosclerotic cardiovascular disease (ASCVD).

METHODS

Six thousand and ninety six participants from the 2017 to 2020 National Health and Nutrition Examination Survey cohort who received a thorough medical health check-up were chosen for the study. The associations between fatty liver status and coronary risk surrogates, such as 10-year ASCVD risk and self-reported cardiovascular events, were analysed.

RESULTS

MAFLD and MASLD were identified in 2911 (47.7%) and 2758 (45.2%) patients, respectively. MAFLD (odds ratio [OR]: 2.14, 95% confidence interval [CI], 1.78-2.57, p < .001) was more strongly independently associated with high ASCVD risk than MASLD (OR: 1.82, 95% CI, 1.52-2.18, p < .001) was in comparison with the absence of each condition. However, compared with MAFLD, MASLD alone was not associated with increased ASCVD risk. Multiple logistic regression revealed that MAFLD alone was significantly more strongly associated with a high risk of ASCVD (OR: 2.82; 95% CI: 1.13-7.01; p < .03) than MASLD alone.

CONCLUSIONS

Although both MAFLD and MASLD were associated with different ASCVD risks, MAFLD predicted the ASCVD risk better than MASLD. The higher predictive ability of MAFLD compared to MASLD was attributed to metabolic dysfunction rather than moderate alcohol use.

Metabolic dysfunction-associated steatotic liver disease: Evolution of the final terminology

The medical term nonalcoholic fatty liver disease (NAFLD) was coined in 1986 for a condition that has since become the most prevalent liver disorder worldwide. In the last 3 years, the global professional community launched 2 consecutive efforts to purge NAFLD from the medical dictionary and recommended new terms based on disease pathophysiology rather than distinction from similar conditions featuring liver steatosis. A consensus by renowned clinical scholars primarily residing in the Asian-Pacific region introduced metabolic dysfunction-associated fatty liver disease (MAFLD) as a new name to replace NAFLD in 2020. In 2023, a nomenclature and classification resulting in the term metabolic dysfunction-associated steatotic liver disease (MASLD) was developed by a large expert panel under the auspices of leading liver societies from Europe and Americas. These marked and rapid shifts in nomenclature have garnered the attention of many researchers and clinicians across the globe due to the multilevel impact of a frequent and potentially progressive chronic liver disease in both adult and pediatric populations. The proposed terminologies differ in several ways but they have more in common than differences. They both capture key features of liver disease associated with cardiometabolic risk factors and with significant impact on all-cause and liver-related mortality. The framework of MASLD has incorporated many innovative aspects of MAFLD and while several conceptual disparities remain a work in progress, global efforts should focus on new insights into disease pathogenesis, outcome trajectories, prevention, and treatment. Here, some of these challenges are discussed to facilitate this process.

MAFLD identifies patients with significant hepatic fibrosis better than MASLD

BACKGROUND AND AIMS

Diagnostic criteria for metabolic dysfunction-associated steatotic liver disease (MASLD) have been proposed but not yet validated. This study aimed to compare the diagnostic accuracy of the MASLD definition with the existing criteria for metabolic dysfunction-associated fatty liver disease (MAFLD) in identifying patients with significant fibrosis.

METHODS

The analysis included a total of 8317 individuals who had complete biochemical and liver ultrasonography data from the National Health and Nutrition Examination Survey (2017-2020). In this study, significant fibrosis (≥ F2) was determined by a median liver stiffness of ≥ 8.0 kPa. To identify independent factors associated with significant fibrosis, multivariable logistic regression analyses were applied.

RESULTS

MAFLD (OR 3.44; 95% CI 2.88-4.12; P < 0.0001) has a trend for stronger and independent association with significant fibrosis compared to MASLD (OR 2.63; 95% CI 2.22-3.11; P < 0.0001). Non-MASLD MAFLD is independently associated with a 14.28-fold higher odds of significant fibrosis compared to non-MAFLD MASLD. The sensitivity for detecting significant fibrosis for MAFLD and MASLD was 76.23% vs 69.94%, respectively. The performance of MAFLD remains consistent in a sub-analysis of patients with no or mild alcohol intake.

CONCLUSIONS

The definition of MAFLD provides a more precise identification of individuals who have both fatty liver and significant fibrosis, assessed by non-invasive tests.

Metabolic Dysfunction-Associated Steatotic Liver Disease: From Pathogenesis to Current Therapeutic Options

The epidemiological burden of liver steatosis associated with metabolic diseases is continuously growing worldwide and in all age classes. This condition generates possible progression of liver damage (i.e., inflammation, fibrosis, cirrhosis, hepatocellular carcinoma) but also independently increases the risk of cardio-metabolic diseases and cancer. In recent years, the terminological evolution from "nonalcoholic fatty liver disease" (NAFLD) to "metabolic dysfunction-associated fatty liver disease" (MAFLD) and, finally, "metabolic dysfunction-associated steatotic liver disease" (MASLD) has been paralleled by increased knowledge of mechanisms linking local (i.e., hepatic) and systemic pathogenic pathways. As a consequence, the need for an appropriate classification of individual phenotypes has been oriented to the investigation of innovative therapeutic tools. Besides the well-known role for lifestyle change, a number of pharmacological approaches have been explored, ranging from antidiabetic drugs to agonists acting on the gut-liver axis and at a systemic level (mainly farnesoid X receptor (FXR) agonists, PPAR agonists, thyroid hormone receptor agonists), anti-fibrotic and anti-inflammatory agents. The intrinsically complex pathophysiological history of MASLD makes the selection of a single effective treatment a major challenge, so far. In this evolving scenario, the cooperation between different stakeholders (including subjects at risk, health professionals, and pharmaceutical industries) could significantly improve the management of disease and the implementation of primary and secondary prevention measures. The high healthcare burden associated with MASLD makes the search for new, effective, and safe drugs a major pressing need, together with an accurate characterization of individual phenotypes. Recent and promising advances indicate that we may soon enter the era of precise and personalized therapy for MASLD/MASH.

Underlying Mechanisms behind the Brain-Gut-Liver Axis and Metabolic-Associated Fatty Liver Disease (MAFLD): An Update

Metabolic-associated fatty liver disease (MAFLD) includes several metabolic dysfunctions caused by dysregulation in the brain-gut-liver axis and, consequently, increases cardiovascular risks and fatty liver dysfunction. In MAFLD, type 2 diabetes mellitus, obesity, and metabolic syndrome are frequently present; these conditions are related to liver lipogenesis and systemic inflammation. This study aimed to review the connection between the brain-gut-liver axis and MAFLD. The inflammatory process, cellular alterations in hepatocytes and stellate cells, hypercaloric diet, and sedentarism aggravate the prognosis of patients with MAFLD. Thus, to understand the modulation of the physiopathology of MAFLD, it is necessary to include the organokines involved in this process (adipokines, myokines, osteokines, and hepatokines) and their clinical relevance to project future perspectives of this condition and bring to light new possibilities in therapeutic approaches. Adipokines are responsible for the activation of distinct cellular signaling in different tissues, such as insulin and pro-inflammatory cytokines, which is important for balancing substances to avoid MAFLD and its progression. Myokines improve the quantity and quality of adipose tissues, contributing to avoiding the development of MAFLD. Finally, hepatokines are decisive in improving or not improving the progression of this disease through the regulation of pro-inflammatory and anti-inflammatory organokines.

The relationship between sarcopenia and metabolic dysfunction-associated fatty liver disease among the young and middle-aged populations

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed as a new term for diagnosing fatty liver disease, which is considered to be a multi-systemic disease with multiple extrahepatic manifestations, including sarcopenia. The link between sarcopenia and MAFLD remains uncertain, especially among young and middle-aged adults. Thus, we examined the relationship between MAFLD and sarcopenia in young and middle-aged individuals in this study.

METHODS

A total of 2214 individuals with laboratory tests, dual-energy X-ray absorptiometry and ultrasound transient elastography from NHANES 2017-2018 were selected for this study. MAFLD was diagnosed as fatty liver disease with any one of the situations: overweight/obesity, diabetes mellitus, presence of metabolic dysregulation. Sarcopenia was defined by appendicular lean mass adjusted for body mass index (BMI). Multivariable logistic regression and restricted cubic spline (RCS) model were applied to explore the relationship between MAFLD and sarcopenia, and the mediation analyses were also conducted. Moreover, subgroup analyses stratified by BMI and lifestyles were done.

RESULTS

The prevalence of MAFLD was 47.85%, and nearly 8.05% of participants had sarcopenia. The prevalence of sarcopenia was higher in participants with MAFLD (12.75%; 95% CI 10.18-15.31%) than in the non-MAFLD (3.73%; 95% CI 2.16-5.31%). MAFLD was significantly positively associated with sarcopenia after adjustments [OR = 2.87 (95% CI: 1.62-5.09)]. Moreover, significant positive associations were observed between liver fibrosis and sarcopenia prevalence in MAFLD patients (OR = 2.16; 95% CI 1.13-4.15). The RCS curve revealed that MAFLD was linearly associated with sarcopenia. The relationship between the MAFLD and sarcopenia were mediated by C-reactive protein (mediation proportion: 15.9%) and high-density lipoprotein cholesterol (mediation proportion: 18.9%). Subgroup analyses confirmed the association between MAFLD and sarcopenia differed in different lifestyle groups.

CONCLUSIONS

Both MAFLD prevalence and severity was significantly associated with sarcopenia. Thus, clinicians should advise comorbidity screening and lifestyle changes to young and middle-aged patients.