Prevalence, clinical characteristics, risk factors, and indicators for lean Chinese adults with nonalcoholic fatty liver disease

Serum uric acid may be a mediator of risk factors in metabolic dysfunction associated steatotic liver disease

BACKGROUND

In recent years, we have witnessed a sharp growth of metabolic dysfunction associated steatotic liver disease (MASLD). How to achieve early prevention of MASLD is imminent. We aimed to determine the dietary pattern and other factors influencing MASLD, to explore whether it mediated by serum uric acid (SUA) or not.

METHODS

A total of 4,038 adults attending the Health Management Center of the Second Affiliated Hospital of Dalian Medical University between October 2018 and May 2019 were surveyed using a questionnaire and underwent physical measurements. Structural equation model (SEM) was used to verify the risk factors and determine the path affecting MASLD.

RESULTS

A total of 3,589 participants were studied. The standardized prevalence of MASLD was 47.8%. Three dietary patterns were identified using factor analysis. The SEM showed that SUA was positively associated with MASLD (standardization coefficient 0.285). In rank order, sex, SUA, dyslipidemia, age, a high-protein diet, and a fast-food diet were risk factors for MASLD. Sex, dyslipidemia, and a fast-food diet had positive and indirect effects on NAFLD through SUA, while age and a high-protein diet had negative and indirect effects on MAFLD through SUA.

CONCLUSIONS

SUA may be an important mediator of the risk of MASLD. People with abnormal SUA, especially men, should limit their intake of fried and cured foods and desserts; have their blood lipid profiles monitored carefully; appropriately increase their consumption of high-quality protein sources, such as eggs, milk, and beans; and be aware of their MASLD risk.

Association of the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio with non-alcoholic fatty liver disease and hepatic steatosis in United States adults: insights from NHANES 2017-2020

Objective

This study aimed to investigate the association between the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and NAFLD, as well as its relationship with hepatic steatosis and liver fibrosis, in a nationally representative sample of U.S. adults.

Methods

This cross-sectional study analyzed data from 3,529 participants from the National Health and Nutrition Examination Survey in 2017-2020. Multivariable logistic regression and subgroup analyses were used to assess the association between NHHR and NAFLD. Multivariate linear regression was employed to evaluate the relationship between NHHR and hepatic steatosis (controlled attenuation parameter) and liver fibrosis (liver stiffness measurement). Nonlinear relationships were explored through fitted smoothing curves and threshold effect analysis. Receiver operating curve (ROC) analysis was performed to compare the diagnostic performance of NHHR with body mass index (BMI), high-density lipoprotein cholesterol (HDL-C), and total cholesterol (TC).

Results

The study included 3,529 participants (mean age: 51.34 years, 95% CI: 49.97, 52.72), with 53.53% male. NHHR showed a significant positive association with NAFLD after adjusting for confounders (OR: 1.33, 95% CI: 1.24, 1.42). Subgroup analysis indicated a stronger association in females and individuals with normal weight. A nonlinear relationship was identified, with a significant positive association below an inflection point of 4 (OR: 1.52, 95% CI: 1.38, 1.68). NHHR was positively associated with hepatic steatosis but not with liver fibrosis. For NAFLD diagnosis, NHHR achieved an area under the curve (AUC) of 0.66, outperforming TC (AUC = 0.51) but indicating lower accuracy than BMI (AUC = 0.77) and HDL-C (AUC = 0.68).

Conclusion

NHHR is positively associated with NAFLD and hepatic steatosis in U.S. population, highlighting the important role of lipid control in the prevention and clinical management of NAFLD.

Hidden in the Fat: Unpacking the Metabolic Tango Between Metabolic Dysfunction-Associated Steatotic Liver Disease and Metabolic Syndrome

Metabolic syndrome (MetS) and metabolic dysfunction-associated steatotic liver disease (MASLD) are closely related, with rapidly increasing prevalence globally, driving significant public health concerns. Both conditions share common pathophysiological mechanisms such as insulin resistance (IR), adipose tissue dysfunction, oxidative stress, and gut microbiota dysbiosis, which contribute to their co-occurrence and progression. While the clinical implications of this overlap, including increased cardiovascular, renal, and hepatic risk, are well recognized, current diagnostic and therapeutic approaches remain insufficient due to the clinical and individuals' heterogeneity and complexity of these diseases. This review aims to provide an in-depth exploration of the molecular mechanisms linking MetS and MASLD, identify critical gaps in our understanding, and highlight existing challenges in early detection and treatment. Despite advancements in biomarkers and therapeutic interventions, the need for a comprehensive, integrated approach remains. The review also discusses emerging therapies targeting specific pathways, the potential of precision medicine, and the growing role of artificial intelligence in enhancing research and clinical management. Future research is urgently needed to combine multi-omics data, precision medicine, and novel biomarkers to better understand the complex interactions between MetS and MASLD. Collaborative, multidisciplinary efforts are essential to develop more effective diagnostic tools and therapies to address these diseases on a global scale.

Lean MASLD and Cardiovascular Disease: A Review

Metabolic-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease, is prevalent worldwide and is highly associated with cardiovascular disease (CVD). Lean MASLD is defined by hepatic steatosis and cardiometabolic risk factors in individuals with a body mass index below 25 in Western populations or below 23 in Asian populations. Paradoxically, some studies indicate that lean MASLD is associated with an elevated risk of cardiovascular (CV) disease and CV mortality compared with nonlean MASLD. Lean MASLD patients exhibit distinctive metabolic, genetic, and microbiome profiles contributing to increased visceral adiposity, sarcopenia, hepatic fibrosis, systemic inflammation, and endothelial dysfunction. This review examines the epidemiology, pathophysiology, and CV outcomes associated with lean MASLD, addressing discrepancies in the literature. Furthermore, it highlights current clinical guidelines, emphasizes lifestyle modifications, and discusses emerging pharmacotherapies as potential treatment options.

Association between TyG-related parameters and NAFLD risk in Japanese non-obese population

Non-alcoholic fatty liver disease (NAFLD) constitutes a substantial proportion of cases among the non-obese population, yet it is frequently overlooked. Studies investigating the association between triglyceride-glucose (TyG)-related parameters (TyG-BMI, TyG-WC, TyG-WHtR) and NAFLD in non-obese individuals is limited. Thus, this study aims to investigate the association between TyG-related parameters and NAFLD in non-obese individuals to improve early detection and intervention strategies for NAFLD in this population. A cross-sectional analysis was conducted using data from the NAFLD database, including 11,987 participants who underwent health examinations between 2004 and 2015. Logistic regression models were employed to evaluate the relationship between TyG-related parameters and NAFLD risk, incorporating cubic spline functions and smooth curve fitting to identify potential nonlinear relationships. ROC curve analysis was conducted to assess the predictive performance of thee parameters. After controlling for confounding variables, the incidence of NAFLD in non-obese individuals increased with higher TyG-related parameters. Notably, nonlinear relationships between the TyG index and its related parameters regarding NAFLD risk were identified. The areas under the ROC curve for the TyG index and its related parameters were 0.7984, 0.8553, 0.8584, and 0.8353, respectively. Importantly, the predictive ability of the TyG index and its related parameters was stronger in the female population than in that of males. A positive and nonlinear relationship exists between the TyG-related parameters in relation to the risk of NAFLD. The TyG-related parameters exhibit predictive capabilities for NAFLD, with TyG-related parameters demonstrating greater strength than the TyG index itself.

The dynamic patterns of metabolic-associated fatty liver disease and its severity and risk of cardiovascular disease

BACKGROUND

While metabolic-associated fatty liver disease (MAFLD) is widely recognized as a risk factor for cardiovascular disease (CVD), the connection between the dynamic patterns of severity of hepatic steatosis and the associated CVD risk remains uncertain.

METHOD

This study included 71,098 participants from the Kailuan Study without CVD or cancer who underwent two consecutive biennial health screenings between 2006 and 2008 and were followed up until 2022. MAFLD and its severity were assessed using ultrasound. Participants were categorized into four groups based on dynamic MAFLD patterns: MAFLD-free, MAFLD-progression, MAFLD-regression, and MAFLD-persistence. MAFLD-regression was further divided into regression from mild MAFLD and regression from moderate/severe MAFLD. Cox proportional hazard regression models analyzed the association between the progression and regression of MAFLD and CVD risk.

RESULT

After a mean follow-up of 12.63 ± 3.16 years, 7838 individuals experienced incident CVD, 5374 had strokes, 1321 had myocardial infarctions, and 1819 developed heart failure. After adjusting for potential confounders, MAFLD-progression was associated with a higher CVD risk compared to MAFLD-free (HR 1.25, 95% CI 1.17-1.33), but this risk decreased with increasing age. Individuals with MAFLD-persistence had the highest CVD risk (HR 1.54, 95% CI 1.46-1.62). Compared to persistent MAFLD, regression from mild MAFLD was associated with a lower CVD risk (HR 0.83, 95% CI 0.76-0.91).

CONCLUSION

The progression of MAFLD can increase the risk of CVD, while regression of MAFLD can decrease the risk of CVD. These findings suggest that the dynamic patterns of MAFLD significantly influence CVD risk.

Natural History of Metabolic Dysfunction-Associated Steatotic Liver Disease: From Metabolic Syndrome to Hepatocellular Carcinoma

Introduction: Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) stems from disrupted lipid metabolism in the liver, often linked to obesity, type 2 diabetes, and dyslipidemia. In Mexico, where obesity affects 36.9% of adults, MASLD prevalence has risen, especially with metabolic syndrome affecting 56.31% by 2018. MASLD can progress to Metabolic Dysfunction-Associated Steatohepatitis (MASH), affecting 5.27% globally, leading to severe complications like cirrhosis and hepatocellular carcinoma. Background: Visceral fat distribution varies by gender, impacting MASLD development due to hormonal influences. Insulin resistance plays a central role in MASLD pathogenesis, exacerbated by high-fat diets and specific fatty acids, leading to hepatic steatosis. Lipotoxicity from saturated fatty acids further damages hepatocytes, triggering inflammation and fibrosis progression in MASH. Diagnosing MASLD traditionally involves invasive liver biopsy, but non-invasive methods like ultrasound and transient elastography are preferred due to their safety and availability. These methods detect liver steatosis and fibrosis with reasonable accuracy, offering alternatives to biopsy despite varying sensitivity and specificity. Conclusions: MASLD as a metabolic disorder underscores its impact on public health, necessitating improved awareness and early management strategies to mitigate its progression to severe liver diseases.

Associations Between GGT/ALT Ratio and Carotid Plaque in Inpatients With Coronary Artery Disease: A RCSCD-TCM Study

This study investigated the relationship between gamma-glutamyltransferase/alanine aminotransferase (GGT/ALT) ratio and carotid plaques in patients with coronary artery disease (CAD). This multicenter retrospective study included 8,255 patients with CAD who were divided according to GGT/ALT quartiles: Q1 (GGT/ALT ≤ 1.00), Q2 (1.00 < GGT/ALT ≤ 1.41), Q3 (1.41 < GGT/ALT ≤ 2.05), and Q4 (GGT/ALT > 2.05). Logistic regression was used to analyze the relationship between GGT/ALT, carotid plaques, and carotid plaque echogenicity. GGT/ALT ratio (odds ratio [OR]: 1.16; 95% confidence interval [CI]: 1.11-1.21; P < .001) was significantly associated with carotid plaque risk. The degree of relevance was higher in men (OR: 1.71; 95% CI: 1.35-2.15; P < .001) than in women (OR: 1.56; 95% CI: 1.28-1.91; P < .001). The ORs value of carotid plaque risk was higher in middle-aged patients (OR: 2.23; 95% CI: 1.78-2.80; P < .001) than in older patients (OR: 1.77; 95% CI: 1.44-2.18; P < .001). The GGT/ALT ratio was significantly associated with different carotid plaque echogenicity, and the highest OR values were for isoechoic plaques (OR: 1.18; 95% CI: 1.12-1.24; P < .001). These findings suggest that the GGT/ALT ratio might be associated with a high risk of developing carotid plaques and different types of plaque echoes and was more significantly associated with isoechoic plaques.

Guideline for the Prevention and Treatment of Metabolic Dysfunction-associated Fatty Liver Disease (Version 2024)

With the rising epidemic of obesity, metabolic syndrome, and type 2 diabetes mellitus in China, metabolic dysfunction-associated non-alcoholic fatty liver disease has become the most prevalent chronic liver disease. This condition frequently occurs in Chinese patients with alcoholic liver disease and chronic hepatitis B. To address the impending public health crisis of non-alcoholic fatty liver disease and its underlying metabolic issues, the Chinese Society of Hepatology and the Chinese Medical Association convened a panel of clinical experts to revise and update the "Guideline of prevention and treatment of non-alcoholic fatty liver disease (2018, China)". The new edition, titled "Guideline for the prevention and treatment of metabolic dysfunction-associated fatty liver disease (Version 2024)", offers comprehensive recommendations on key clinical issues, including screening and monitoring, diagnosis and evaluation, treatment, and follow-up for metabolic dysfunction-associated fatty liver disease and metabolic dysfunction-associated steatotic liver disease. Metabolic dysfunction-associated fatty liver disease is now the preferred English term and is used interchangeably with metabolic dysfunction-associated steatotic liver disease. Additionally, the guideline emphasizes the importance of multidisciplinary collaboration among hepatologists and other specialists to manage cardiometabolic disorders and liver disease effectively.

Diagnosis and Management of Lean Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): A Systematic Review

Lean metabolic dysfunction-associated steatotic liver disease (MASLD) defies traditional views of fatty liver diseases by manifesting in nonobese individuals. The renaming from nonalcoholic fatty liver disease to MASLD underscores a broader understanding of its pathophysiology, highlighting the complex interplay of metabolic factors beyond obesity. Despite its clinical importance, diagnosing and managing lean MASLD remains challenging due to its historical ties to obesity and a general lack of awareness about its unique characteristics. On December 4, 2023, a systematic literature search was conducted across six databases, focusing on peer-reviewed studies in English related to the diagnosis and management of lean MASLD. This study was registered with the International Prospective Register of Systematic Reviews (CRD42023489308). Out of 95 studies following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 43 addressed diagnosis and surveillance, whereas 52 explored management strategies. The results revealed the difficulties in diagnosing lean MASLD, pointing out the limitations of traditional markers and the potential of advanced imaging techniques. Management strategies discussed included lifestyle changes and possible pharmacological treatments tailored to the specific metabolic features of this patient group. The study highlights the necessity for increased clinical awareness, regular monitoring, and personalized therapeutic approaches for lean MASLD. It calls for further research to refine diagnostic criteria and develop targeted treatments, aiming to enhance care for individuals with lean MASLD.

Clinical value of -glutamyl transpeptidase to platelet ratio and triglyceride measurement in the diagnosis of nonalcoholic fatty liver disease: A cross-sectional study

OBJECTIVE

In clinical practice, there are few effective biomarkers for identifying non-alcoholic fatty liver disease (NAFLD). The aim of this study is to investigate the diagnostic value of γ-glutamyl transpeptidase to platelet ratio (GPR) combined with triglyceride (TG) in NAFLD.

METHODS

A total of 14,415 individuals participated in the annual physical examination. Multivariate logistic regression analysis was conducted to investigate the exposure factors associated with NAFLD. Spearman's analysis was performed to assess the correlation among the exposure factors of NAFLD. Furthermore, the diagnostic efficacy of the combination of GPR and TG in NAFLD was analyzed using the receiver operating characteristic curve (ROC).

RESULTS

The results of the multivariate logistic regression analysis showed that BMI (OR = 1.619), Systolic Blood Pressure (SBP) (OR = 1.014), Diastolic Blood Pressure (DBP) (OR = 1.028), GPR (OR = 12.809), and TG (OR = 2.936) were all risk factors for NAFLD, while HDL-C (OR = 0.215) was a protective factor. Spearman correlation analysis revealed significant positive correlations between GPR and SBP, DBP, BMI, TG (p < 0.01), but a negative correlation between GPR and HDL-C (p < 0.01). TG was only positively correlated with GPR (p < 0.001). ROC curve analysis demonstrated that the area under the curve (AUC) of GPR combined with TG for diagnosis of NAFLD was 0.855 (95 % CI: 0.819-0.891), sensitivity was 83.45 % and specificity was 73.56 %.

CONCLUSION

This study indicated that high levels of GPR and TG were risk factors for NAFLD and demonstrated good clinical value in diagnosing NAFLD.

Usefulness of Neck Circumference, Waist-to-Height Ratio and Waist-to-Hip Ratio in Predicting Non-Alcoholic Fatty Liver Disease in Saudi Population Without Type 2 Diabetes

Background

Early identification and treatment of non-alcoholic fatty liver disease (NAFLD) could reduce overall mortality. Anthropometric measurements offer a simple and cost-effective method to potentially improve early detection of NAFLD and prevent its complications. This study aims to estimate the prevalence of NAFLD using the fatty liver index (FLI) and evaluate the effectiveness of certain anthropometric measurements in predicting NAFLD as diagnosed by FLI.

Method

A cross-sectional analytical study was conducted with 1264 Saudi population without Type 2 diabetes mellitus (T2DM) non-alcoholic individuals at primary health care centers (PHCCs) in Jeddah city. Measurements included triglycerides, gamma-glutamyl transferase (GGT), glycated hemoglobin (HbA1c), and fasting plasma glucose (FPG). Measurements for neck circumference (NC), and calculations for weight-to-height ratio (WHtR) and weight-to-hip ratio (WHpR), along with FLI, were performed. NAFLD was identified in individuals with an FLI ⩾60. The receiver operating characteristic (ROC) curve analysis was utilized to assess the accuracy of WHtR, WHpR, and NC in detecting NAFLD, with Youden's index determining the optimal cutoff points for these 3 indices.

Result

The prevalence of NAFLD was found to be 30.9%. Among the markers, WHtR emerged as the most significant in indicating NAFLD, achieving an area under the curve (AUC) of 0.916; whereas NC and WHpR exhibited identical AUC values of 0.783. WHtR demonstrated superior diagnostic efficacy for identifying elevated FLI, with gender-specific cutoff values established at >0.57 for females and >0.61 for males. In all 3 markers, females exhibited higher sensitivity, specificity, and negative predictive value (NPV) compared to males.

Conclusion

WHtR could serve as a useful tool in the initial clinical screening for NAFLD among Saudi population without T2DM to identify those who may benefit from more comprehensive testing. Further local studies are warranted to confirm the levels of accuracy and the calculated cutoffs.

Effects of Interventions for Improving Awareness and Knowledge of Nonalcoholic Fatty Liver Disease Among Chinese Young Adults for Prevention of Liver Cancer-A Randomized Controlled Trial

Chinese young adults (CYA), who are at an increasing risk of developing nonalcoholic fatty liver disease (NAFLD), which in turn increases the risk of liver cancer, are an ideal target population to deliver educational interventions to improve their awareness and knowledge of NAFLD and consequently reduce their risk of developing NAFLD. The purpose of this study was to determine the efficacy of two interventions to improve awareness and knowledge of NAFLD among CYA for the prevention of liver cancer. Between May and July 2021, 1373 undergraduate students aged 18 to 25 years in one university in China completed a web-based, self-administered survey distributed through WeChat app. One week after completion of the baseline survey, all eligible participants were randomly assigned to a pamphlet, a video intervention, or no intervention (control group), with follow-up assessments immediately and 1-month post-intervention. The 7-page pamphlet or 6.5-min video had information on NAFLD. Self-assessments included NAFLD awareness, lean NAFLD awareness, and knowledge scores of NAFLD. About 26% of participants had NAFLD awareness at baseline. Compared with controls, participants in both interventions showed significant improvement of awareness of NAFLD (pamphlet, + 46.0%; video, + 44.3%; control, + 18.7%; OR [95% CI], 3.13 [2.19-4.47] and 2.84 [1.98-4.08]), awareness of lean NAFLD (pamphlet, + 41.2%; video, + 43.0%; control, + 14.5%; OR [95% CI], 2.84 [1.62-4.99] and 2.61 [1.50-4.54]), and knowledge score of NAFLD (pamphlet, + 64.2%; video, + 68.9%; control, - 1.0%; OR [95% CI], 1.62 [1.47-1.80] and 1.67 [1.50-1.86]) at immediately post-intervention. Delivering NAFLD education through a pamphlet or video intervention was effective in improving the awareness and knowledge of NAFLD among CYA.

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.

Association between the ZJU index and risk of new-onset non-alcoholic fatty liver disease in non-obese participants: a Chinese longitudinal prospective cohort study

Background

Non-alcoholic fatty liver disease (NAFLD) is increasingly observed in non-obese individuals. The ZJU (Zhejiang University) index has been established as a new and efficient tool for detecting NAFLD, but the relationship between the ZJU index and NAFLD within non-obese individuals still remains unclear.

Methods

A post-hoc evaluation was undertaken using data from a health assessment database by the Wenzhou Medical Center. The participants were divided into four groups based on the quartile of the ZJU Index. Cox proportional hazards regression, Kaplan-Meier analysis and tests for linear trends were used to evaluate the relationship between the ZJU index and NAFLD incidence. Subgroup analysis was conducted to test the consistency of the correlation between ZJU and NAFLD in subsgroups. Receiver operative characteristic (ROC) curve analysis was performed to evaluate the predictive performance of the ZJU index, compared with the Atherogenic index of plasma (AIP) and Remnant lipoprotein cholesterol (RLP-C) index.

Results

A total of 12,127 were included in this study, and 2,147 participants (17.7%) developed NAFLD in 5 years follow-up. Participants in higher ZJU quartiles tended to be female and have higher liver enzymes (including ALP, GGT, ALT, AST), GLU, TC, TG, LDL and higher NAFLD risk. Hazard Ratios (HR) and 95% confidence intervals (CI) for new-onset NAFLD in Q2, Q3, and Q4 were 3.67(2.43 to 5.55), 9.82(6.67 to 14.45), and 21.67(14.82 to 31.69) respectively in the fully adjusted model 3. With increased ZJU index, the cumulative new-onset NAFLD gradually increased. Significant linear associations were observed between the ZJU index and new-onset NAFLD (p for trend all<0.001). In the subgroup analysis, we noted a significant interaction in sex, with HRs of 3.27 (2.81, 3.80) in female and 2.41 (2.21, 2.63) in male (P for interaction<0.01). The ZJU index outperformed other indices with an area under the curve (AUC) of 0.823, followed by AIP (AUC=0.747) and RLP-C (AUC=0.668).

Conclusion

The ZJU index emerges as a promising tool for predicting NAFLD risk in non-obese individuals, outperforming other existing parameters including AIP and RLP-C. This could potentially aid in early detection and intervention in this specific demographic.

Effect of exercise and pharmacotherapy on non-alcoholic fatty liver disease

OBJECTIVES

Nonalcoholic fatty liver disease is one of the emerging liver diseases affecting 20%-30% of the population creating a burden on public health worldwide and has been associated with the causation of multiple diseases. Besides exercise, several drugs are being used in patients based on clinical evidence especially vitamin E, a potent antioxidant to reduce the oxidative stress responsible for the development and progression of nonalcoholic fatty liver disease. This study aims at evaluating the effect of exercise and pharmacotherapy on nonalcoholic fatty liver disease.

DESIGN

A prospective follow-up study with purposive sampling was done at a liver clinic for 3 months. Baseline characteristics such as anthropometric measurements and biochemical parameters were recorded and compared after 3 months to determine the effect of therapy. Descriptive analysis using a parametric test was used to assess the change in biochemical parameters and a non-parametric test was applied to find out the association between non-pharmacological and pharmacological approaches.

RESULTS

Out of 177 patients, 67.2 % were male and 32.8% were female with the mean age ±SD of 46.8 ± 12.06 years. Mean ± SD weight and body mass index of the patients were changed from 74.88 ± 11.61 kg to 72.37 ± 11.61 kg and from 28.41 ± 4.02 kg/m2 to 27.31 ± 4.58 kg/m2 respectively which was found to be statistically significant. There was a significant change in all the biochemical parameters with the p-value < 0.05 through both non-pharmacological and pharmacological approaches.

CONCLUSION

Nonalcoholic fatty liver disease management through exercise and pharmacotherapy shows significant improvement in biochemical parameters indicating that alone or in combination with both approaches play an effective role in treating nonalcoholic fatty liver disease.

Genetic and epigenetic determinants of non-alcoholic fatty liver disease (NAFLD) in lean individuals: a systematic review

Background

Non-alcoholic fatty liver disease (NAFLD) is common in obese individuals, but its occurrence in lean individuals and the underlying mechanisms are not well understood. This study aimed to systematically review the literature on the genetic and epigenetic factors influencing NAFLD in lean individuals.

Methods

A comprehensive search was conducted on April 2nd, 2023, in seven databases using specific criteria. Only peer-reviewed studies in English, focusing on genetic or epigenetic effects on NAFLD in lean individuals, were included for qualitative synthesis. The Newcastle Ottawa Scale (NOS) was used for quality assessment. This study is registered with PROSPERO (CRD42023413809).

Results

Following PRISMA guidelines, 18 studies were included in this review. The studies were conducted globally, with varying sample sizes and study designs. The NOS quality assessment revealed a moderate overall quality with variations in risk of bias and limitations in comparability and ascertainments of exposure among contributing studies. Genetic determinants related to lipid metabolism, inflammation, and oxidative stress pathways were identified, including PNPLA3 and TM6SF2 gene variants associated with increased NAFLD risk in lean individuals. Epigenetic modifications, particularly depletion of histone variants, were also implicated. However, some studies found no significant associations between genetic or clinical characteristics and lean NAFLD. Less frequent genetic risk factors, such as CETP and APOC3 gene variants, were reported.

Conclusions

This systematic review underscores the importance of investigating genetic and epigenetic factors in lean NAFLD. The findings highlight the role of PNPLA3 and TM6SF2 gene variants and suggest potential epigenetic contributions. Further research is needed to fully understand the genetic and epigenetic mechanisms underlying NAFLD in lean individuals.

Clinical Classification of Obesity and Implications for Metabolic Dysfunction-Associated Fatty Liver Disease and Treatment

Obesity,and metabolic dysfunction-associated fatty liver disease (MAFLD) have reached epidemic proportions globally. Obesity and MAFLD frequently coexist and act synergistically to increase the risk of adverse clinical outcomes (both hepatic and extrahepatic). Type 2 diabetes mellitus (T2DM) is the most important risk factor for rapid progression of steatohepatitis and advanced fibrosis. Conversely, the later stages of MAFLD are associated with an increased risk of T2DM incident. According to the proposed criteria, MAFLD is diagnosed in patients with liver steatosis and in at least one in three: overweight or obese, T2DM, or signs of metabolic dysregulation if they are of normal weight. However, the clinical classification and correlation between obesity and MAFLD is more complex than expected. In addition, treatment for obesity and MAFLD are associated with a reduced risk of T2DM, suggesting that liver-based treatments could reduce the risk of developing T2DM. This review describes the clinical classification of obesity and MAFLD, discusses the clinical features of various types of obesity and MAFLD, emphasizes the role of visceral obesity and insulin resistance (IR) in the development of MAFLD,and summarizes the existing treatments for obesity and MAFLD that reduce the risk of developing T2DM.

The role of TRIM family in metabolic associated fatty liver disease

Metabolic associated fatty liver disease (MAFLD) ranks among the most prevalent chronic liver conditions globally. At present, the mechanism of MAFLD has not been fully elucidated. Tripartite motif (TRIM) protein is a kind of protein with E3 ubiquitin ligase activity, which participates in highly diversified cell activities and processes. It not only plays an important role in innate immunity, but also participates in liver steatosis, insulin resistance and other processes. In this review, we focused on the role of TRIM family in metabolic associated fatty liver disease. We also introduced the structure and functions of TRIM proteins. We summarized the TRIM family's regulation involved in the occurrence and development of metabolic associated fatty liver disease, as well as insulin resistance. We deeply discussed the potential of TRIM proteins as targets for the treatment of metabolic associated fatty liver disease.

Analysis of the association between dietary patterns and nonalcoholic fatty liver disease in a county in Guangxi

BACKGROUND

This study aims to investigate the relationship between different dietary patterns and non-alcoholic fatty liver disease (NAFLD).

METHODS

Residents over 30 years old in the ecological longevity cohort in Gongcheng Yao Autonomous County, Guangxi Province were the research objects selected from 2018 to 2019. Physical examination, baseline population survey, and food frequency questionnaire (FFQ) survey were conducted. Dietary patterns were analyzed by factor analysis. Influencing factors of NAFLD were analyzed by multiple logistic regression.

RESULTS

NAFLD was diagnosed in 241 of 2664 participants based on ultrasonography, and the detection rate was 9.0%. Factor analysis yielded a total of three dietary patterns, namely, traditional Chinese, Western, and cereal-potato dietary patterns. Results of multivariate logistic regression analysis showed that after adjusting for confounding factors, participants in the highest quartile of the Western dietary pattern exhibited a higher prevalence of NAFLD (OR = 2.799; 95% CI: 1.620-4.837; p < 0.05) than participants in the lowest quartile. Participants in the highest quartile of the cereal-potato pattern exhibited a decreased risk of NAFLD compared with those in the lowest quartile (OR = 0.581; 95% CI: 0.371-0.910, p < 0.05). The traditional Chinese patterns did not show any association with the risk of NAFLD.

CONCLUSIONS

The Western dietary pattern increases the risk of NAFLD, whereas the cereal-potato dietary pattern reduces the risk of NAFLD. It is important for the prevention and control of NAFLD to adhere to the cereal-potato dietary.

Comparison of cardiometabolic risk factors between obese and non-obese patients with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is closely associated with cardiometabolic abnormalities. This association could be partly influenced by weight, but not entirely. This study aimed to compare the cardiometabolic risk factors between obese and non-obese NAFLD patients, and explored the relationship between adiposity and severity of fatty liver. This cross-sectional study included 452 patients with Fibroscan-proven NAFLD. Anthropometric measurements, metabolic components and hepatic histological features were evaluated. The risk of metabolic syndrome in each body mass index (BMI) category was analyzed using logistic regression. The prevalence of metabolic syndrome was 10.2%, 27.7%, and 62.1% in normal-weight, overweight and obese participants. Regression analysis showed that the risk of metabolic syndrome in overweight and obese NAFLD patients was 3.74 and 4.85 times higher than in patients with normal weight, respectively. Waist circumference (β = 0.770, P < 0.001) and serum concentration of fasting blood glucose (β = 0.193, P = 0.002) and triglyceride (β = 0.432, P < 0.001) were the determinants of metabolic syndrome occurrence in NAFLD patients. Metabolic abnormalities were similar in obese and non-obese NAFLD patients, although, the increase in BMI was associated with an increased risk of metabolic syndrome in patients.

Epidemiology of lean/non-obese nonalcoholic fatty liver disease in China: A systematic review and meta-analysis

OBJECTIVES

To assess the prevalence and metabolic characteristics of lean/non-obese (L/NO) nonalcoholic fatty liver disease (NAFLD) in China.

METHODS

The databses, inlcuding PubMed, Web of Science, EMBASE, as well as Cochrane databases, were retrieved for eligible studies. The prevalence together with clinical features of L/NO-NAFLD in China were analyzed using a random/fixed effects model. Lean or nonobese participants were characterized by the cut-offs of body mass index used in original studies. Heterogeneity was identified using meta-regression and subgroup analyses.

RESULTS

We included 25 studies for the final analysis comprising 229091 L/NO Chinese adults and 22641 diagnosed with NAFLD, with the NAFLD prevalence of 8.98% (95% confidence interval [CI]: [5.55-13.13] for L-NAFLD Chinese participants and 13.77% (95% CI: [11.13-16.63]) for NO-NAFLD Chinese participants. This prevalence gradually increased during the past few years. The community and health checkup populations presented similar prevalence (14.19% vs. 13.55%). Meanwhile, L/NO patients with NAFLD showed lower blood pressure (128.86/80.48 vs. 136.09/84.98 mmHg), waist circumference (80.63 vs. 92.73 cm), fasting blood glucose (5.53 vs. 5.69 mmol/L), uric acid (339.14 vs. 365.46 μmol/L), triglyceride levels (1.63 vs. 1.94 mmol/L), alanine transaminase (30.28 vs. 33.12 IU/L), and γ-glutamyl transferase (29.9 vs. 43.68 IU/L), but higher levels of high-density lipoprotein cholesterol (1.33 vs. 1.26 mmol/L) compared to overweight/obese (OW/O) patients with NAFLD.

CONCLUSION

Prevalence of NAFLD was slightly lower among the L/NO-NAFLD Chinese population than the global level but has obviously increased recently. In addition, the metabolic profile of L/NO-NAFLD patients was generally better compared to OW/O-NAFLD patients.PROSPERO Reg. No.: CRD42022327240.

Impact renaming non-alcoholic fatty liver disease to metabolic associated fatty liver disease in prevalence, characteristics and risk factors

BACKGROUND

Recently, a group of hepatologists proposed to rename non-alcoholic fatty liver disease (NAFLD) as metabolic associated fatty liver disease (MAFLD) with modified diagnostic criteria. It is important to note, however, that there are some differences between the diagnostic criteria used for NAFLD and MAFLD. Since the research on MAFLD is just beginning, however, evidence on its incidence and prevalence in the general population and in specific subpopulations remains limited.

AIM

To assess epidemiology of fatty liver in new definition and compare MAFLD with NAFLD. Exploring risk factors of MAFLD individuals.

METHODS

This was a retrospective, cross-sectional study. A total of 85242 adults were selected from the Chinese health management database in 2017-2022. The data of general information, laboratory indicators, lifestyle management and psychological status were obtained. MAFLD was diagnosed as ultrasound diagnosis of fatty liver and at least one between these three conditions: Overweight/obesity, type 2 diabetes mellitus (T2DM) or metabolic dysregulation. Metabolic factors were not considered in NAFLD diagnosis standard. The clinical characteristics of MAFLD and NAFLD were analysed using descriptive statistics. Continuous variables normally distributed were expressed as means ± SD. Categorical variables were expressed as frequencies and proportions. Binary logistic regression was used to determine risk factors of the MAFLD.

RESULTS

The prevalence of MAFLD and NAFLD was 40.5% and 31.0%, respectively. The MAFLD or NAFLD population is more likely to be older (M: 47.19 ± 10.82 vs 43.43 ± 11.96; N: 47.72 ± 11.17 vs 43.71 ± 11.66), male (M: 77.21% vs 44.43%; N: 67.90% vs 53.12%) and high body mass index (M: 26.79 ± 2.69 vs 22.44 ± 2.48; N: 26.29 ± 2.84 vs 23.29 ± 3.12) than the non-MAFLD or non-MAFLD population. In multivariate analysis, general information (e.g., ≥ 2 metabolic abnormalities OR = 3.38, (95%CI: 2.99-3.81), P < 0.001; diastolic blood pressure OR = 1.01, (95%CI: 1.00-1.01), P = 0.002), laboratory results [e.g.,total bilirubin (TBIL) OR = 0.98, (95%CI: 0.98-0.99), P < 0.001; serum uric acid(SUA) OR = 1.01, (95%CI: 1.01-1.01), P < 0.001], and lifestyle factors [e.g., drink beverage OR = 0.32, (95%CI: 0.17-0.63), P = 0.001] were influence factors for MAFLD. Our study results offer new insight into potential risk factors associated with fatty liver disease, including SUA, TBIL and creatinine, all of which are related to chronic renal disease (CKD).

CONCLUSION

MAFLD is more prevalent than NAFLD, with two-fifths of individuals meeting the diagnosis criteria. MAFLD and NAFLD populations have different clinical characteristics. CKD may be related with MAFLD.

Non-Traditional Blood Lipid Indices for Metabolism Dysfunction-Associated Fatty Liver Disease Prediction in Non-Obese Type 2 Diabetes Mellitus

Objective

This study aims to investigate the predictive value of non-traditional blood lipid indices for metabolism dysfunction-associated fatty liver disease (MAFLD) in non-overweight/obese patients with type 2 diabetes mellitus (T2DM).

Methods

A retrospective observational study was conducted, including non-overweight/obese patients with T2DM who visited the Fourth Hospital of Hebei Medical University between August 2018 and August 2022. The low-density lipoprotein cholesterol (LDL-C)/high-density lipoprotein cholesterol (HDL-C) ratio, the triacylglycerol-glucose index (TyG) multiplied by body mass index (BMI), and TyG/HDL-C ratio were calculated.

Results

The study involved 190 participants, of whom 34 were diagnosed with MAFLD (24 males and 10 females), while 156 did not have MAFLD (64 males and 92 females). Multivariable analysis revealed that aspartate transaminase (AST) (OR=1.216, 95% CI: 1.059-1.374, P=0.006), blood uric acid (BUA) (OR=1.017, 95% CI: 1.002-1.032, P=0.022), TyG*BMI (OR=1.231, 95% CI: 1.051-1.442, P=0.010), and TyG/HDL-C (OR=3.162, 95% CI: 1.228-8.141, P=0.017) were independently associated with MAFLD. The TyG*BMI index exhibited an area under the ROC curve (AUC) of 0.812, with 91.2% sensitivity and 69.2% specificity for MAFLD. The TyG/HDL-C index had an AUC of 0.929, with 85.3% sensitivity and 88.5% specificity for MAFLD.

Conclusion

The results indicate that TyG*BMI and TyG/HDL-C are independently associated with MAFLD in non-overweight/obese patients with T2DM.

Waist to height ratio in nonalcoholic fatty liver disease - Systematic review and meta-analysis

BACKGROUND AND AIMS

Current nonalcoholic fatty liver disease (NAFLD) guidelines do not provide any recommendations regarding the waist-to-height ratio (WHtR), a simple obesity metric calculated by dividing waist circumference by height. Therefore, we performed a systematic review and meta-analysis aiming to evaluate WHtR in NAFLD.

METHODS

We performed a systematic electronic search on PubMed, Embase, and Scopus, identifying observational studies assessing WHtR in NAFLD. QUADAS-2 tool was used to evaluate the quality of included studies. The two main statistical outcomes were the area under the curve (AUC) and the mean difference (MD).

RESULTS

We included a total of 27 studies in our quantitative and qualitative synthesis, with a total population of 93,536 individuals. WHtR was significantly higher in NAFLD patients compared to controls with an MD of 0.073 (95% CI 0.058 - 0.088). This was also confirmed after conducting a subgroup analysis according to the hepatic steatosis diagnosis method, for ultrasound (MD 0.066 [96% CI 0.051 - 0.081]) and transient elastography (MD 0.074 [96% CI 0.053 - 0.094]). Moreover, NAFLD male patients presented significantly lower WHtR compared to female patients (MD -0.022 [95% CI -0.041 - -0.004]). The AUC of WHtR for predicting NAFLD was 0.815 (95% CI 0.780 - 0.849).

CONCLUSIONS

WHtR is considerably higher in NAFLD patients compared to controls. Female NAFLD patients present higher WHtR compared to NAFLD male patients. In comparison to other presently suggested scores and markers, the WHtR's accuracy in predicting NAFLD is considered acceptable.

Nonalcoholic Fatty Liver Disease in Lean/Nonobese and Obese Individuals: A Comprehensive Review on Prevalence, Pathogenesis, Clinical Outcomes, and Treatment

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, with an estimated prevalence of 25% globally. NAFLD is closely associated with metabolic syndrome, which are both becoming increasingly more common with increasing rates of insulin resistance, dyslipidemia, and hypertension. Although NAFLD is strongly associated with obesity, lean or nonobese NAFLD is a relatively new phenotype and occurs in patients without increased waist circumference and with or without visceral fat. Currently, there is limited literature comparing and illustrating the differences between lean/nonobese and obese NAFLD patients with regard to risk factors, pathophysiology, and clinical outcomes. In this review, we aim to define and further delineate different phenotypes of NAFLD and present a comprehensive review on the prevalence, incidence, risk factors, genetic predisposition, and pathophysiology. Furthermore, we discuss and compare the clinical outcomes, such as insulin resistance, dyslipidemia, hypertension, coronary artery disease, mortality, and progression to nonalcoholic steatohepatitis, among lean/nonobese and obese NAFLD patients. Finally, we summarize the most up to date current management of NAFLD, including lifestyle interventions, pharmacologic therapies, and surgical options.

Epidemiological characteristics and management of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis in China: A narrative review

AIM

With industrialization and spread of the westernized lifestyle, the number of people affected by non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) is growing rapidly in China; this has become a major public health concern. To better understand the burden and characteristics of NAFLD/NASH in China, we aim to perform a narrative review of the literature published in this field.

MATERIALS AND METHODS

We carried out a comprehensive electronic search of five English-language and three Chinese-language databases, to identify studies regarding NAFLD or NASH published from inception to November 30, 2022. Epidemiological studies of NAFLD/NASH in China were particularly noticed and summarized. We also searched the www.

CLINICALTRIALS

gov and www.chictr.org.cn websites for the registered trials on the treatment of the disease led by Chinese investigators or located in China.

RESULTS

The increasing rate of NAFLD prevalence in China is strikingly high, reaching more than twice that in western countries. The prevalence of NAFLD is nearly 30% of the general Chinese population, making it the leading cause of chronic liver diseases. The prevalence of NAFLD/NASH varies between provinces/regions, age groups, sexes, and individuals with different metabolic profiles. NAFLD co-exists in many Chinese patients with chronic hepatitis B. Since 2020, more Chinese studies have used the term metabolic-associated fatty liver disease (MAFLD), emphasizing the underlying metabolic disorders that occur concurrently with this disease. Several clinical trials involving lifestyle interventions, antidiabetic drugs, or traditional Chinese medicines, registered by Chinese investigators, have been completed or are ongoing. Moreover, several innovative targeted therapies developed in China are revolutionizing the treatment of NAFLD/NASH.

CONCLUSIONS

NAFLD has cast a heavy burden on the Chinese healthcare system. Chinese scholars are making efforts to achieve the optimal management of this disease.

Surveillance of the progression and assessment of treatment endpoints for nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is an aggressive form of nonalcoholic fatty liver disease (NAFLD) characterized by steatosis-associated inflammation and liver injury. Without effective treatment or management, NASH can have life-threatening outcomes. Evaluation and identification of NASH patients at risk for adverse outcomes are therefore important. Key issues in screening NASH patients are the assessment of advanced fibrosis, differentiation of NASH from simple steatosis, and monitoring of dynamic changes during follow-up and treatment. Currently, NASH staging and evaluation of the effectiveness for drugs still rely on pathological diagnosis, despite sample error issues and the subjectivity associated with liver biopsy. Optimizing the pathological assessment of liver biopsy samples and developing noninvasive surrogate methods for accessible, accurate, and safe evaluation are therefore critical. Although noninvasive methods including elastography, serum soluble biomarkers, and combined models have been implemented in the last decade, noninvasive diagnostic measurements are not widely applied in clinical practice. More work remains to be done in establishing cost-effective strategies both for screening for at-risk NASH patients and identifying changes in disease severity. In this review, we summarize the current state of noninvasive methods for detecting steatosis, steatohepatitis, and fibrosis in patients with NASH, and discuss noninvasive assessments for screening at-risk patients with a focus on the characteristics that should be monitored at follow-up.

Unique genetic variants of lean nonalcoholic fatty liver disease: a retrospective cohort study

We investigated the prevalence and clinical metabolic characteristics of lean nonalcoholic fatty liver disease (NAFLD) in an elderly Chinese population and assessed the relevance of lipid markers and genetic variation. All 5,338 community subjects underwent detailed clinical and laboratory examinations and were divided into three groups: lean (Body mass index (BMI) < 23 kg/m², n = 2,012), overweight (BMI = 23-24.9 kg/m², n = 1,354), and obese (BMI ≥ 25 kg/m², n = 1,972). Single nucleotide polymorphisms were selected based on those reported in previous NAFLD or obesity genome-wide association studies. The frequencies of alleles and genotypes were calculated and statistically analyzed with Pearson's χ² tests. One-way ANCOVA was used to test the association between positive SNPs and metabolic parameters in lean NAFLD individuals. Our results showed that the C allele frequency of rs2279026, the G allele of rs2279028, the C allele of rs780093, and the C allele frequency of rs1260326 were higher in obese NAFLD than in lean NAFLD (P < 0.05). In addition, we observed an association between the CC of rs1421085, TT of rs3751812, AA of rs8050136, and AA of rs9939609 genotypes in the FTO gene and low-density lipoprotein levels (P < 0.05). In conclusion, our findings provide a unique perspective on the prevalence, genetic characteristics, and metabolic profile of NAFLD in older lean individuals in China. This is the first study to examine the association between genetic variants in the FTO, TFAP2B and GCKR genes and NAFLD in a cohort of lean individuals.

Metabolic (dysfunction)-associated fatty liver disease in individuals of normal weight

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) affects up to a third of the global population; its burden has grown in parallel with rising rates of type 2 diabetes mellitus and obesity. MAFLD increases the risk of end-stage liver disease, hepatocellular carcinoma, death and liver transplantation and has extrahepatic consequences, including cardiometabolic disease and cancers. Although typically associated with obesity, there is accumulating evidence that not all people with overweight or obesity develop fatty liver disease. On the other hand, a considerable proportion of patients with MAFLD are of normal weight, indicating the importance of metabolic health in the pathogenesis of the disease regardless of body mass index. The clinical profile, natural history and pathophysiology of patients with so-called lean MAFLD are not well characterized. In this Review, we provide epidemiological data on this group of patients and consider overall metabolic health and metabolic adaptation as a framework to best explain the pathogenesis of MAFLD and its heterogeneity in individuals of normal weight and in those who are above normal weight. This framework provides a conceptual schema for interrogating the MAFLD phenotype in individuals of normal weight that can translate to novel approaches for diagnosis and patient care.

Comparative Burden of Metabolic Dysfunction in Lean NAFLD vs Non-lean NAFLD - A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is traditionally associated with obesity. However, there is a subtype of NAFLD, namely NAFLD in lean, that occurs without obesity. However, a recent call to redefine NAFLD to metabolic-associated fatty liver disease focuses on obesity and metabolic dysfunction. Criticism has arisen from the perceived over emphasis on systemic comorbidities, which may disadvantage the lean. The current analysis seeks to quantify the degree of metabolic dysfunction in NAFLD in lean and compare with NAFLD in overweight and obese and non-NAFLD.

METHODS

Medline and Embase databases were searched from inception to March 3, 2022. The inclusion criteria were articles with NAFLD in lean patients presenting with baseline metabolic parameters. Comparisons were conducted with subgroup analysis.

RESULTS

Eighty-five articles were included in the meta-analysis. NAFLD in lean accounted for 13.11% (95% confidence interval [CI], 10.26%-16.62%) of the global population and 14.55% (95% CI, 11.32%-18.51%) in Asia. The degree of metabolic dysfunction was weight dependent with significantly less metabolic dysfunction in NAFLD in lean subjects as compared with NAFLD in overweight counterparts. For NAFLD in lean, only 19.56% (95% CI, 15.28%-24.69%) of the subjects were diabetic, whereas 45.70% (95% CI, 35.01%-56.80%) of obese subjects with NAFLD had diabetes (P < .01). Fasting blood glucose and systolic and diastolic blood pressure values were significantly lower in subjects with NAFLD in lean than in overweight and obese.

CONCLUSION

The current analysis highlights the weight-dependent nature of metabolic dysfunction in NAFLD. Lean subjects with NAFLD were significantly less metabolically unhealthy than were obese and overweight persons with NAFLD. An overreliance on metabolic dysfunction in defining fatty liver will be a flaw in potentially excluding previously characterized NAFLD.

Prediction and validation of nonalcoholic fatty liver disease by fatty liver index in a Japanese population

Fatty liver index (FLI) calculated by using body mass index (BMI), waist circumference and levels of γ-glutamyl transferase and triglycerides is a non-invasive predictor of nonalcoholic fatty liver disease (NAFLD). The original study in Italy showed that the cutoff level for prediction of NAFLD was FLI ≥60. However, the sex difference in FLI was not taken into consideration, and it is unclear whether the cutoff value can be applied to other races. We investigated the cutoff value of FLI for prediction of NAFLD determined by abdominal ultrasonography using receiver operating characteristic curve analyses in 14,471 Japanese subjects (men/women: 9,240/5,231; mean age: 48 ± 9 years). There was a significant interaction between sex and FLI for detection of NAFLD (p < 0.001). The cutoff values of FLI in men and women were 35.1 (area under the curve [AUC]: 0.82) and 15.6 (AUC: 0.91), respectively. When the subjects were divided by the absence and presence of obesity (BMI ≥25), there was a significant interaction between FLI and obesity for detection of NAFLD in women (p < 0.001) but not in men (p = 0.679). The cutoff values of FLI in non-obese/obese men and women were 22.6/52.6 and 11.2/33.2, respectively. In conclusion, the cutoff value of FLI for prediction of NAFLD in Japanese individuals was lower than that in the original study, and there is a significant sex difference. The simple and useful cutoff values in Japanese men and women are FLI ≥35 (non-obese/obese: 23/53) and FLI ≥16 (non-obese/obese: 11/33), respectively.

Triglyceride: A mediator of the association between waist-to-height ratio and non-alcoholic fatty liver disease: A second analysis of a population-based study

OBJECTIVE

Increasing evidence suggests that an increased waist-to-height ratio (WHtR) may increase the risk of non-alcoholic fatty liver disease (NAFLD). Whether this association is due to WHtR itself or mediated by WHtR-associated increases in triglyceride (TG) is uncertain. On that account, our research aims to disentangle these relationships.

METHODS

In this cross-sectional study, 14251 participants who participated in the medical examination program were consecutively and non-selectively collected in Murakami Memorial Hospital in Japan from 2004 to 2015. The independent and dependent variables were WHtR and NAFLD, respectively. Triglyceride was the mediating factor. The correlation between WHtR, TG, and NAFLD risk factors was examined using spearman correlation analysis. The association between WHtR or TG and NAFLD was examined using multiple logistic regression. In order to determine whether TG mediated the association between WHtR and NAFLD, a mediation analysis was performed.

RESULTS

The mean age of the included individuals was 43.53 ± 8.89 years old, and 7411 (52.00%) were male. The mean WHtR and TG were 0.46 ± 0.05, 0.89 ± 0.63, respectively. The prevalence rate of NAFLD was 2507 (17.59%). Individuals with NAFLD had significantly higher levels of WHtR and TG than those without NAFLD (P&lt;0.05). After adjusting covariates, the multivariate linear regression analysis showed that WHtR was positively associated with TG. That was, for every 0.1 increase in WHtR, TG increased by 0.226mmol/L (β=0.226, 95%CI: 0.206, 0.247). Multiple logistic regression analysis indicated that WHtR (OR=8.743, 95%CI: 7.528, 10.153) and TG (OR=1.897, 95%CI: 1.732, 2.078) were positively associated with NAFLD. The mediation analysis showed that WHtR had a direct, significant effect on NAFLD (β=0.139, 95%CI: 0.126, 0.148), and TG partially mediated the indirect effect of WHtR on NAFLD (β=0.016, 95% CI: 0.013-0.019). TG contributed to 10.41% of WHtR-related NAFLD development.

CONCLUSION

Findings suggest a mediation link between WHtR and TG and the risk of NAFLD. The significance of TG as a mediator deserves recognition and consideration.

Association between the atherogenic index of plasma and new-onset non-alcoholic fatty liver disease in non-obese participants

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) in the non-obese population accounts for a large proportion of NAFLD. Atherogenic index of plasma (AIP, defined as the logarithm of the triglyceride/high-density lipoprotein cholesterol ratio.) can provide a stronger reflection of dyslipidemia and studies on the longitudinal association between AIP and NAFLD were limited in non-obese participants, especially in different BMI groups.

METHODS

We performed a post-hoc analysis of data obtained from the Dryad data repository (Dryad is a nonprofit open database of medicine.) and explored the predictive value of AIP on the risk of NAFLD among non-obese participants.

RESULTS

This study included 16173 participants with AIP, of which 2322(14.4%) non-obese participants developed into individuals with NAFLD with the 5-year follow-up examination. The difference between AIP quartiles in the cumulative estimation of new-onset NAFLD was significant, and with increased AIP, the cumulative new-onset NAFLD gradually increased. Participants in higher AIP quartiles had a significantly increased risk of NAFLD. In the fully adjusted model 3, hazard ratios of the new-onset NAFLD for subjects in Q2, Q3, and Q4 of AIP were 2.00 (1.59, 2.53), 2.61 (2.09, 3.72), and 4.49 (3.62, 5.57) respectively. Meanwhile, the trend test for the association between AIP quartiles and the new-onset NAFLD presented that AIP quartile was positively and strongly associated with the new-onset NAFLD (adjusted hazard ratio (95%CI) in Model 3: 1.59 (1.51, 1.67), P<0.001). We found that AIP was also positively and strongly associated with new-onset NAFLD in different sex groups and different age groups in female patients. Moreover, the predictive ability of AIP was no significant difference in different sex groups and different age groups in female patients. In the subgroup analysis, we found that in the low BMI population, the predictive effect of AIP for new-onset NAFLD was expanded by 2-3 times for each quality increase of AIP.

CONCLUSION

This study found that AIP was a strong independent risk factor for new-onset NAFLD among non-obese individuals especially in the low BMI participants, and screening for AIP in this population can be used to prevent future NAFLD.

Risk Factors for Nonalcoholic Fatty Liver Disease with Different Insulin Resistance in a Nonobese Chinese Population

PURPOSES

The aim of this study is to identify the risk factors of nonobese nonalcoholic fatty liver disease (NAFLD) individuals under different insulin resistance status.

METHODS

This cross-sectional study was conducted at the Medical Center of Beijing Chaoyang Hospital affiliated with Capital Medical University. NAFLD was diagnosed based upon ultrasonographic findings consistent with fatty liver disease.

RESULTS

A total of 1257 nonobese adults (625 non-NAFLD and 632 nonobese NAFLD) with body mass index (BMI) 18.5-24.9 kg/m² were enrolled in the study. And all patients were divided into homeostasis model assessment of insulin resistance (HOMA - IR) > 1 group and HOMA - IR ≤ 1 group. When all the variables were adjusted in both the HOMA - IR > 1 group and HOMA - IR ≤ 1 group, older age (>50 years), higher BMI (23.0-24.9 kg/m²), higher AST (>18 U/L), higher TG (>0.9 mmol/L), higher GLU (>5.25 mmol/L), and higher HbA1C (>5.5%) were associated with higher risks of nonobese NAFLD. In patients with HOMA - IR > 1, lower homeostatic model assessment of β-cell function (HOMA-β) (<47.1%) (OR, 7.460, 95% CI, 3.051-18.238, P < 0.001) was associated with higher risks of nonobese NAFLD.

CONCLUSION

s. Metabolic profiles (i.e., higher BMI, hyperglycemia, hypertriglyceridemia, and higher glycosylated hemoglobin) are risk factors of nonobese NAFLD, regardless of insulin resistance status. Decreased function of pancreatic β-cells may be the risk factor of nonobese NAFLD with insulin resistance, who should pay attention to further development of pancreatic β-cell dysfunction.

Bile acids induced hepatic lipid accumulation in mice by inhibiting mRNA expression of patatin-like phospholipase domain containing 3 and microsomal triglyceride transfer protein

Preliminary studies have shown that a lithogenic diet (LG), which contains cholesterol and cholic acid, induces gallstones and hepatic lipid accumulation (HLA), and reduction of blood triglyceride in mice. We hypothesized that an LG induces HLA by diminishing hepatic triglyceride excretion; however, there is no clear understanding of the mechanism of LG-induced HLA. This study aimed to investigate transcript expression related to the synthesis, expenditure, and efflux of hepatic triglyceride, in mice fed an LG for 4 weeks. Results showed lower plasma concentrations of triglyceride in the LG group than in the control group, but no symptoms of hepatic injury were observed. Hepatic mRNA expressions of patatin-like phospholipase domain containing 3 (Pnpla3), microsomal triglyceride transfer protein (Mttp), and acyl-CoA oxidase 1 (Acox1) were also reduced in the LG group. Deoxycholic acid and lithocholic acid promoted intracellular lipid accumulation, reduced triglyceride concentration in media, and suppressed expression of PNPLA3 and MTTP in HepG2 human hepatoma cells. These findings suggest that deoxycholic acid and lithocholic acid promote HLA by inhibiting the expression of PNPLA3, ACOX1, and MTTP that are involved in lipid metabolism.

Comparison of clinical and metabolic profiles of lean versus non-lean nonalcoholic fatty liver disease

BACKGROUND

Data on nonalcoholic fatty liver disease (NAFLD) in the Philippines are scarce. We aimed to compare the clinical and biochemical profiles of lean (BMI<23) vs. non-lean (BMI≥23) NAFLD patients.

METHODS

Consecutive patients diagnosed with NAFLD on ultrasound in two outpatient hepatology clinics from February 2007-January 2017 were included. Patients with significant alcohol intake, alternative causes of steatosis, and incomplete data were excluded.

RESULTS

A total of 663 patients (57.9% male) were included. Most patients were non-lean (88.1%) and had an elevated alanine aminotransferase (ALT) (63%). Cirrhosis or hepatocellular carcinoma (HCC) were already present in 8.4% on initial consultation. Concomitant hepatitis B was equally common in patients with and without cirrhosis (20.7% vs. 17.5%; p=0.660) or HCC (17.9% vs. 12.8%; p=0.415). Independent factors associated with HCC/cirrhosis on initial consultation were older age (OR=1.038), low albumin (OR=0.428), high BARD score (BMI, AST/ALT ratio, T2 diabetes mellitus; OR=2.548) and the presence of symptoms (OR=1.808). Compared to lean NAFLD patients, non-lean patients were more likely to be younger (51.5±14.4 vs. 55±14.3; p=0.003), have DM (47.9% vs. 29.1%; p=0.002), hypertension (57.5% vs. 38%; p=0.001), dyslipidemia (73.1% vs. 54.4%; p=0.001) and metabolic syndrome (60.3% vs. 30.4%; p<0.0001), abnormal metabolic parameters (LDL-C, HDL-C, triglycerides, uric acid and FBS), and with elevated ALT (65.2% vs. 46.8%; p=0.002) and AST (41.1±29.6 vs. 35.3±28.3; p=0.008).

CONCLUSIONS

The proportion of lean NAFLD was 11.9%. Although metabolic derangements and its clinical consequences were present in about a third of lean patients, these were still more common in non-lean NAFLD. Cirrhosis or HCC were already present in a significant proportion (8.4%) of NAFLD patients on initial presentation.

A review of non-alcoholic fatty liver disease in non-obese and lean individuals

Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of hepatic disorders. It represents a wide range of chronic liver diseases in patients with no history of significant alcohol consumption, starting with simple steatosis and progressing towards non-alcoholic steatohepatitis, cirrhosis, and ultimately hepatocellular carcinoma. NAFLD is usually associated with type 2 diabetes mellitus, dyslipidemia, metabolic syndrome, and obesity. This disease has mostly been studied in obese individuals; however, it has been widely reported and studied among the lean/non-obese population in recent years. The pathogenesis of NAFLD in non-obese patients is associated with various genetic predispositions, particularly a patatin-like phospholipase domain-containing protein 3 G allele polymorphism, which results in the accumulation of triglyceride in the liver and resistance to insulin. Additionally, dietary factors such as high fructose consumption seem to play a substantial role in the pathology of non-obese NAFLD. Although there is not enough evidence on the treatment of NAFLD in non-obese patients, the standard approach is to advise altering one's lifestyle in order to diminish visceral adiposity. Dietary modification, weight loss, and increased physical activity are highly recommended. We aimed to review and summarize the existing information on the prevalence, pathogenesis, genetic predispositions, diagnosis, and treatment of NAFLD in non-obese patients according to the latest literature.

Waist-to-height ratio and non-alcoholic fatty liver disease in adults

Background

The waist-to-height ratio (WHtR) has been recognised as a powerful indicator to evaluate non-alcoholic fatty liver disease (NAFLD) in recent years, but few related studies are available. Thus, clarifying the association between the WHtR and NAFLD may be beneficial to the prevention and treatment of NAFLD.

Methods

The cross-sectional study population was from a large-scale health examination programme called ‘human dock’ in Japan. In this study, 14,125 participants in this health examination programme were included. To understand the association between the WHtR and NAFLD more intuitively, we grouped the WHtR values into quintiles and used a multivariable logistic regression model to assess WHtR and its quintile with NAFLD risk. Moreover, we used the generalised additive model to model the association between WHtR and NAFLD to explore their non-linear relationship.

Results

The prevalence of NAFLD among participants in this study was 17.59%, with an average age of 43.53 ± 8.89 years. After adjusting for all non-collinear covariables, we observed a 66% increase in the NAFLD risk per SD increase in WHtR. Furthermore, in the quintile groups of WHtR, the participants in quintile 2, quintile 3, quintile 4, and quintile 5 had 3.62-fold, 5.98-fold, 9.55-fold, and 11.08-fold increased risks of NAFLD, respectively, compared with those in quintile 1 (P_trend < 0.0001). Non-linear relationship analysis revealed threshold and saturation effects between WHtR and NAFLD in which a WHtR of approximately 0.4 might be the threshold effect of NAFLD risk, 0.6 might be the saturation effect of NAFLD risk. Additionally, subgroup analysis showed that the interaction between WHtR and BMI was significant.

Conclusions

Our results suggest that in adults, the WHtR is associated with NAFLD, and the association is not purely linear but non-linear, with significant threshold and saturation effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01824-3.

Low serum vitamin D concentrations are associated with obese but not lean NAFLD: a cross-sectional study

BACKGROUND

A low serum vitamin D concentration has been reported to be associated with an increased risk of non-alcoholic fatty liver disease (NAFLD); however, whether lean or obese individuals show a similar association between vitamin D and NAFLD remains speculative. This study aimed to explore the relationship between serum vitamin D concentration and NAFLD in lean and obese Chinese adults.

METHODS

This cross-sectional study included 2538 participants (1360 men and 1178 women) who underwent health checkups at the First Affiliated Hospital, Zhejiang University School of Medicine in 2019. NAFLD was diagnosed by liver ultrasound excluding other causes. The association of serum vitamin D concentration with NAFLD was analyzed in lean and obese participants.

RESULTS

The overall prevalence of NAFLD was 33.61% (13.10% in lean and 53.32% in obese) in this study population. The serum vitamin D levels of obese NAFLD patients were lower than those of obese NAFLD-free controls. However, the serum vitamin D levels of lean NAFLD patients were comparable to those of lean NAFLD-free controls. Serum vitamin D level was negatively correlated with the prevalence of NAFLD in obese but not lean participants. Serum vitamin D level was independently associated with the risk of NAFLD in obese participants, with an adjusted odds ratio (95% CI) of 0.987 (0.981-0.993). However, serum vitamin D level was not related to the risk of NAFLD in lean participants.

CONCLUSIONS

A low serum vitamin D level is associated with NAFLD in obese but not lean participants.

Shifting perspectives - interplay between non-alcoholic fatty liver disease and insulin resistance in lean individuals

Non-alcoholic fatty liver disease (NAFLD) has become a significant public health burden affecting not only obese individuals but also people with normal weight. As opposed to previous beliefs, this particular subset of patients has an increased risk of all-cause mortality and worse outcomes than their obese counterparts. The development of NAFLD in lean subjects seems to be interconnected with metabolic phenotype, precisely visceral fat tissue, sarcopenia, and insulin resistance. Here, we summarize available data focusing on the co-dependent relationship between metabolic phenotype, insulin resistance, and development of NAFLD in lean individuals, suggesting more appropriate tools for measuring body fat distribution for the screening of patients at risk.

Epidemiology, Pathogenesis, Diagnosis and Emerging Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, with an estimated rising prevalence, in concert with the epidemics of obesity and type 2 diabetes. The pathogenesis of NAFLD is not fully elucidated. Besides weight gain and insulin resistance, many other factors seem to contribute, including adipokines, gut microbiota and genetic predisposition. The disease starts as hepatic steatosis, which may proceed to nonalcoholic steatohepatitis (NASH); if fibrosis is added, the risk of cirrhosis and/or hepatocellular carcinoma is augmented. Liver biopsy is considered the gold standard for the diagnosis and staging of NAFLD; the early use of reliable and easily applied diagnostic tools, such as noninvasive biomarkers, is needed to identify patients at different-preferably early-stages of disease however. Whilst lifestyle modification is the first step to manage NAFLD, there is poor compliance, leading to the need of drug therapy. Accordingly, a variety of medications is under investigation. Given the multifaceted pathophysiology of NAFLD, probably, a combination of approaches in an individualized basis may be a more appropriate management. This review summarizes evidence on the epidemiology, pathogenesis, diagnosis and treatment of NAFLD.

MAFLD vs. NAFLD: shared features and potential changes in epidemiology, pathophysiology, diagnosis, and pharmacotherapy

ABSTRACT

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, placing an increasing burden on human health. NAFLD is a complex multifactorial disease involving genetic, metabolic, and environmental factors. It is closely associated with metabolic syndrome, obesity, and type 2 diabetes, of which insulin resistance is the main pathophysiological mechanism. Over the past few decades, investigation of the pathogenesis, diagnosis, and treatments has revealed different aspects of NAFLD, challenging the accuracy of definition and therapeutic strategy for the clinical practice. Recently, experts reach a consensus that NAFLD does not reflect the current knowledge, and metabolic (dysfunction) associated fatty liver disease (MAFLD) is suggested as a more appropriate term. The new definition puts increased emphasis on the important role of metabolic dysfunction in it. Herein, the shared features and potential changes in epidemiology, pathophysiology, diagnosis, and pharmacotherapy of the newly defined MAFLD, as compared with the formerly defined NAFLD, are reviewed for updating our understanding.

Nonalcoholic fatty liver disease in lean subjects: Prognosis, outcomes and management

Nonalcoholic fatty liver disease (NAFLD) accounts for most cases of chronic liver disease worldwide, with an estimated global prevalence of approximately 25% and ranges from simple steatosis to nonalcoholic steatohepatitis and cirrhosis. NAFLD is strongly connected to metabolic syndrome, and for many years, fatty liver was considered to be an exclusive feature of obese patients. However, recent studies have highlighted the presence of NAFLD in non-obese subjects, with or without increased visceral fat or even in lean subjects without increased waist circumference. "Lean NAFLD" is a relatively new concept and there is significant scientific interest in understanding the differences in pathophysiology, prognosis and management compared with NAFLD in overweight/obese patients. In the present editorial, we discuss the clinical and metabolic profiles and outcomes of lean NAFLD compared with both obese NAFLD and lean healthy individuals from Asian and Western countries. Moreover, we shed light to the challenging topic of management of NAFLD in lean subjects since there are no specific guidelines for this population. Finally, we discuss open questions and issues to be addressed in the future in order to categorize NAFLD patients into lean and non-lean cohorts.