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

Metabolic dysfunction associated steatotic liver disease is associated with an increased risk of multiple respiratory system diseases

Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a significant public health concern. However, the relationship between MAFLD and different types of respiratory diseases is not yet fully understood. In UK Biobank prospective cohort, 11 types of respiratory diseases were identified according to the ICD-10 codes. Cox regression was used to determine the association between MASLD and respiratory disease risk. A total of 393,416 subjects with an average age of 56.6 years were included, MASLD patients account for 34.9%. After fully adjustment for confounding factors, 9 out of 11 respiratory diseases were significantly associated with MASLD, including influenza (hazard ratio (HR): 1.294), pneumonia (HR: 1.258), chronic lower respiratory diseases (HR: 1.297), asthma (HR: 1.222), lung diseases due to external agents (HR: 1.190), interstitial lung diseases (HR: 1.336), diseases of the pleura (HR: 1.175), pulmonary embolism (HR: 1.225), lung and bronchus cancer (HR: 1.212) and respiratory system death (HR: 1.108) (P < 0.05 for all). The risk of respiratory diseases increases with the severity of MASLD assessed by fibrosis score. The relationship between the MASLD phenotype and respiratory diseases is independent of polygenic risk scores and four related risk alleles. These findings emphasize the value of comprehensive prevention of respiratory diseases by targeting MASLD.

Metabolic dysfunction-associated steatotic liver disease, metabolic alcohol-related liver disease, and incident dementia: a nationwide cohort study : MASLD, MetALD, and dementia risk

BACKGROUND

The relationship between the newly proposed steatotic liver disease (SLD) subtypes-metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic alcohol-associated liver disease (MetALD)-and dementia is understudied. We evaluated the dementia risk associated with these subtypes.

METHODS

This retrospective cohort study included 296,001 participants aged over 60 who underwent health examinations between 2009 and 2010. Participants were categorized into non-SLD (reference), MASLD, and MetALD groups and followed up until dementia onset, death, or December 31, 2019. SLD was defined by a fatty liver index ≥ 30, with (i) MASLD based on cardiometabolic risk factors, and (ii) MetALD as MASLD with moderate alcohol intake. Outcomes included overall dementia, Alzheimer's disease (AD), and vascular dementia (VaD). Subdistribution hazard ratios (SHRs) was calculated using the Fine-Gray model, treating death as a competing risk.

RESULTS

Over 7,430,253 person-years of follow-up, 11,345 dementia cases occurred (10,863 AD and 2,159 VaD). Adjusted SHRs for MASLD were 1.10 (1.07-1.13) for AD and 1.20 (1.13-1.27) for VaD. For MetALD, SHRs were 0.90 (0.87-0.94) for AD and 1.53 (1.40-1.66) for VaD. Dementia risk in both MASLD and MetALD increased over longer periods, with MetALD initially linked to increased VaD risk and decreased AD risk, which reversed after three years.

CONCLUSIONS

MASLD and MetALD were associated with increased risks of AD and VaD; MetALD showing a stronger association with VaD. Understanding the distinct effects of different SLD subtypes on dementia is crucial for improving risk assessment and management strategies.

Lean Metabolic Dysfunction-Associated Steatotic Liver Disease: A Comparative Analysis of Hepatic and Oncological Outcomes

GOALS

To compare outcomes of MASLD in obese and nonobese populations.

BACKGROUND

MASLD is emerging as one of the leading causes of liver failure and liver-related morbidity and mortality, with an increasing prevalence in the nonobese or lean population. The purpose of this study is to compare hepatic and oncological outcomes between MASLD patients with lean BMI and nonlean BMI.

STUDY

The National Inpatient Sample (NIS) was queried from 2016 to 2020 for adult hospitalizations with MASLD. Exclusion criteria included concurrent diagnoses of viral hepatitis, alcoholic hepatitis, primary biliary cholangitis, hereditary hemochromatosis, autoimmune hepatitis, or Wilson disease. Outcomes of MASLD and its complications were compared between the lean and nonlean subgroups.

RESULTS

Patients with lean BMI had higher mortality rates (odds ratio: 2.10, P<0.001). The lean cohort also had higher odds of cirrhosis, portal hypertension, SBP, and ascites. The lean subgroup had higher odds of gastrointestinal malignancies including esophageal cancer, gastric cancer, pancreatic cancer, and colorectal cancer.

CONCLUSIONS

Hospitalized lean MASLD patients had higher odds of mortality, ​​hepatic morbidities, and gastrointestinal malignancies. These results challenge the use of BMI as a predictor of morbidity and mortality for MASLD patients. Future studies should focus on therapeutic options for MASLD and compare their efficacies between lean and nonlean populations.

Metabolic dysfunction-associated steatotic liver disease: heterogeneous pathomechanisms and effectiveness of metabolism-based treatment

The global epidemic of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing worldwide. People with MASLD can progress to cirrhosis and hepatocellular carcinoma and are at increased risk of developing type 2 diabetes, cardiovascular disease, chronic kidney disease, and extrahepatic cancers. Most people with MASLD die from cardiac-related causes. This outcome is attributed to the shared pathogenesis of MASLD and cardiometabolic diseases, involving unhealthy dietary habits, dysfunctional adipose tissue, insulin resistance, and subclinical inflammation. In addition, the steatotic and inflamed liver affects the vasculature and heart via increased glucose production and release of procoagulant factors, dyslipidaemia, and dysregulated release of hepatokines and microRNAs. However, there is substantial heterogeneity in the contributors to the pathophysiology of MASLD, which might influence its rate of progression, its relationship with cardiometabolic diseases, and the response to therapy. The most effective non-pharmacological treatment approaches for people with MASLD include weight loss. Paradoxically, some effective pharmacological approaches to improve liver health in people with MASLD are associated with no change in bodyweight or even with weight gain, and similar response heterogeneity has been observed for changes in cardiometabolic risk factors. In this Review, we address the heterogeneity of MASLD with respect to its pathogenesis, outcomes, and metabolism-based treatment responses. Although there is currently insufficient evidence for the implementation of precision medicine for risk prediction, prevention, and treatment of MASLD, we discuss whether knowledge about this heterogeneity might help achieving this goal in the future.

Fatty liver index as an independent predictor of all-cause and disease-specific mortality

PURPOSE

This study aims to assess the prognostic value of the fatty liver index (FLI), a noninvasive tool for hepatic steatosis assessment, in predicting all-cause and disease-specific mortality.

METHODS

We linked data from the National Health and Nutrition Examination Survey III (1988-1994) with Public-Use Mortality Files, forming a cohort of 11 297 participants with a median follow-up period of 26.25 years. Cox proportional hazards models were used to evaluate the association between FLI and all-cause mortality, while Fine and Gray's models assessed the relationship between FLI and disease-specific mortality.

RESULTS

The FLI ≥ 60 was independently associated with an increased risk of all-cause mortality (hazard ratio = 1.24, P  < 0.001), as well as mortality from malignant neoplasms (hazard ratio = 1.18, P  = 0.048), diabetes (hazard ratio = 2.62, P  = 0.001), and cardiovascular diseases (CVDs) (hazard ratio = 1.18, P  = 0.018), compared to FLI < 30. No significant associations were found with Alzheimer's disease, influenza and pneumonia, chronic lower respiratory diseases, or renal disorders. Subgroup analyses indicated that individuals who were females aged 40-60 (hazard ratio = 1.67, P  = 0.003), non-overweight (hazard ratio = 1.75, P  = 0.007), or without abdominal obesity (hazard ratio = 1.75, P  = 0.007) exhibited a stronger association between FLI ≥ 60 and all-cause mortality.

CONCLUSION

These findings support the prognostic value of the FLI for predicting mortality from all causes, malignant neoplasms, diabetes, and CVDs. Targeted attention is needed in postmenopausal women, non-overweight, and non-abdominally obese populations.

Propylthiouracil Induced Rat Model Reflects Heterogeneity Observed in Clinically Non-Obese Subjects with Nonalcoholic Fatty Liver Disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing, affecting up to 30% of the population, with approximately 20% of cases occurring in non-obese individuals. The recent shift to the term metabolic dysfunction-associated steatosis liver disease (MASLD) highlights the disease's heterogeneity. However, there are no well-established animal models replicating non-obese NAFLD (NO-NAFLD). This study aimed to evaluate the relevance of the high-fat diet (HFD) combined with the propylthiouracil (PTU)-induced rat model in mimicking the histopathology and pathophysiology of NO-NAFLD. We first analyzed metabolic and clinical parameters between NO-NAFLD patients (Average BMI = 21.96 kg/m2) and obese NAFLD patients (Average BMI = 29.7 kg/m2). NO-NAFLD patients exhibited significantly higher levels of carnitines, phospholipids, and triglycerides. In the animal model, we examined serum lipid profiles, liver inflammation, histology, and transcriptomics. Hepatic steatosis in the HFD+PTU model at week 4 was comparable to that of the HFD model at week 8. The HFD+PTU model showed higher levels of carnitines, phospholipids, and triglycerides, supporting its relevance for NO-NAFLD. Additionally, the downregulation of lipid synthesis-related genes indicated differences in lipid accumulation between the two models. Overall, the HFD+PTU-induced rat model is a promising tool for studying the molecular mechanisms of NO-NAFLD.

Investigation of the risk factors associated with prediabetes in normal-weight Qatari adults: a cross-sectional study

Type 2 diabetes is one of the most prevalent chronic diseases in the world, and more people than ever before have impaired glucose tolereance, or prediabetes. Many patients with impaired glucose tolerance and undiagnosed diabetes do not know that their glucose metabolism system has been in a state of disorder. Every year, about 5-10% of prediabetics develop diabetes. One of the important achieving factors may be the increase in blood lipids. However, it is not clear whether triglyceride is associated with impaired glucose tolerance and prediabetes in the Qatari population. Therefore, we investigated the relationship between the first several clinical variables and prediabetes status in normal and overweight populations. We conducted a cross-sectional study using data from the Qatar Biobank program. The study included 5,996 participants who were adults over the age of 20. We collected information about participants' fasting blood glucose levels with other clinical measurements and used various machine learning models and logistic regression to study the association between the clinical measurements and prediabetes for normal and overobese weight groups. The use of several machine learning models showed that, after adjusting the potential confounding factors such as age and sex, Triglyceride has been demonstrated to be positively correlated with prediabetes, and there was a special population dependence phenomenon. Among them, nonobese people (p < 0.05). The effect value and 95% confidence interval and OR of triglyceride on prediabetes was 2.79 and (e0.78, e1.28), respectively.

Liver and cardiovascular outcomes in lean non-alcoholic fatty liver disease: an updated systematic review and meta-analysis of about 1 million individuals

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) is present in lean people. However, the magnitude of the prognostic hepatic and cardiovascular risk in these patients compared to non-lean counterparts remains unclear. We aimed to investigate this topic, and to explore whether these risks change based on factors related to NAFLD severity.

METHODS

PubMed and Embase databases were searched for cohort studies (published through April 2024) that evaluated liver and cardiovascular (CV) outcomes in lean and non-lean individuals with NAFLD and reported unadjusted or adjusted data. We pooled risk ratios (RRs) or hazard ratios (HRs) using a random-effects modeling and performed subgroup and meta-regressions analyses.

RESULTS

We identified 22 studies with over 1 million NAFLD patients (13.0% were lean). Lean NAFLD showed a similar risk of liver-related events in unadjusted analysis (RR 1.08, 95% CI 0.79-1.49, I2 = 31%), but a higher risk in adjusted analysis (HR 1.66, 95% CI 1.17-2.36, I2 = 83%) compared to non-lean NAFLD. Lean NAFLD had a higher risk of liver-related mortality (RR 2.22, 95% CI 1.57-3.15, I2 = 0%; HR 2.26, 95% CI 1.14-4.51, I2 = 0%). For CV outcomes, lean NAFLD had a lower risk of any cardiovascular disease in unadjusted analysis (RR = 0.82, 95% CI 0.70-0.95, I2 = 88%), but similar risk in adjusted analysis (HR 0.89, 95% CI 0.77-1.02, I2 = 78%), and similar risk of cardiovascular mortality (RR 1.09, 95% CI 0.71-1.66, I2 = 85%; HR 1.26, 95% CI 0.89-1.78, I2 = 46%) compared to non-lean NAFLD.

CONCLUSIONS

Lean NAFLD patients have worse liver outcomes, but similar CV outcomes compared to non-lean NAFLD patients, highlighting the importance of monitoring both groups closely.

Exploring Fibrosis Pathophysiology in Lean and Obese Metabolic-Associated Fatty Liver Disease: An In-Depth Comparison

While obesity-related nonalcoholic fatty liver disease (NAFLD) is linked with metabolic dysfunctions such as insulin resistance and adipose tissue inflammation, lean NAFLD more often progresses to liver fibrosis even in the absence of metabolic syndrome. This review aims to summarize the current knowledge regarding the mechanisms of liver fibrosis in lean NAFLD. The most commonly used lean NAFLD models include a methionine/choline-deficient (MCD) diet, a high-fat diet with carbon tetrachloride (CCl4), and a high-fructose and high-cholesterol diet. The major pro-fibrogenic mechanisms in lean NAFLD models include increased activation of the extracellular signal-regulated kinase (ERK) pathway, elevated expression of α-smooth muscle actin (α-SMA), collagen type I, and TGF-β, and modulation of fibrogenic markers such as tenascin-X and metalloproteinase inhibitors. Additionally, activation of macrophage signaling pathways promoting hepatic stellate cell (HSC) activation further contributes to fibrosis development. Animal models cannot cover all clinical features that are evident in patients with lean or obese NAFLD, implicating the need for novel models, as well as for deeper comparisons of clinical and experimental studies. Having in mind the prevalence of fibrosis in lean NAFLD patients, by addressing specific pathways, clinical studies can reveal new targeted therapies along with novel biomarkers for early detection and enhancement of clinical management for lean NAFLD patients.

Association between nonalcoholic fatty liver disease and gallstone risk in nonobese and lean individuals

PURPOSE

The association between nonobese/lean nonalcoholic fatty liver disease (NAFLD) and gallstone formation remains unclear. We aimed to assess whether NAFLD is an independent risk factor for gallstones, even in nonobese or lean individuals.

METHODS

We analyzed 265 353 asymptomatic adults who underwent abdominal ultrasonography. The risk of gallstone was assessed on the basis of obesity and NAFLD status.

RESULTS

The overall prevalence rates of NAFLD and gallstones were 27.1% and 2.6%, respectively. The prevalence rates of NAFLD among the 195 204 nonobese and 136 194 lean participants were 14.7% and 7.4%, respectively. Individuals with NAFLD had a significantly increased risk of gallstones (adjusted odds ratio [OR], 1.23; 95% confidence interval [CI], 1.14-1.32). Moreover, NAFLD significantly increased the risk of gallstone (adjusted OR, 1.29; 95% CI, 1.17-1.41) among nonobese individuals. Lean individuals with NAFLD also exhibited a significantly increased risk of gallstones (adjusted OR, 1.20; 95% CI, 1.03-1.40). Furthermore, these findings remained consistent even in nonobese and lean individuals without insulin resistance.

CONCLUSION

Nonobese/lean NAFLD is an independent risk factor for gallstone formation, suggesting its role in gallstone pathogenesis, regardless of obesity status. Therefore, when hepatic steatosis is detected on abdominal ultrasonography, a more thorough evaluation of the gallstones may be necessary, even in nonobese or lean individuals.

Impact of metabolic phenotype and alcohol consumption on mortality risk in metabolic dysfunction-associated fatty liver disease: a population-based cohort study

Patients with metabolic dysfunction-associated fatty liver disease (MAFLD) often present with concomitant metabolic dysregulation and alcohol consumption, potentially leading to distinct clinical outcomes. We analyzed data from 8043 participants with MAFLD in the Thai National Health Examination Survey with linked mortality records. According to the MAFLD criteria, 1432 individuals (17.2%) were categorized as having the diabetes phenotype, 5894 (71.0%) as the overweight/obesity phenotype, and 978 (11.8%) as the lean metabolic phenotype. Over 71,145 person-years, 916 participants died. Using Cox proportional hazard models adjusting for physiological, lifestyle, and comorbid factors, both diabetes (adjusted hazards ratio [aHR] 1.59, 95% CI 1.18-2.13) and lean metabolic phenotypes (aHR 1.28, 95% CI 1.01-1.64) exhibited significantly higher mortality risk compared to the overweight/obesity phenotype. A J-shaped relationship was observed between daily alcohol consumption and the risk of all-cause mortality. Daily alcohol intake exceeding 50 g for women and 60 g for men increased the all-cause mortality risk among MAFLD individuals with the lean metabolic phenotype (aHR 3.39, 95% CI 1.02-11.29). Our study found that metabolic phenotype and alcohol consumption have interactive effects on the risk of all-cause mortality in patients with MAFLD, indicating that evaluating both factors is crucial for determining prognostic outcomes and management strategies.