Impact of sarcopenia on the progression of nonalcoholic fatty liver disease: a frequently forgotten association

Steatotic liver disease-associated all-cause/cause-specific mortality in the United States

BACKGROUND

Recently, a panel of multi-society experts proposed steatotic liver disease (SLD) as an alternative terminology for metabolic dysfunction-associated fatty liver disease (MAFLD) or nonalcoholic fatty liver disease (NAFLD).

AIMS

We compared the impact of SLD, subtype of SLD, MAFLD and NAFLD on all-cause and cause-specific mortality.

METHODS

A total of 7811 individuals in the third National Health and Nutrition Examination Survey and linked mortality through 2019 were analysed. SLD was defined based on ultrasonographic hepatic steatosis. SLD, subtype of SLD and MAFLD were defined using the proposed definitions. The Cox proportional hazard model assessed all-cause/cause-specific mortality.

RESULTS

During a median follow-up of 27.1 years, individuals with SLD and MAFLD experienced approximately 13%-23% higher risk of all-cause mortality (hazard ratio [HR]: 1.15, 95% confidence interval [CI]: 1.02-1.29 for SLD; HR: 1.23, 95% CI: 1.09-1.38 for MAFLD; HR: 1.13, 95% CI: 1.01-1.27 for metabolic dysfunction-associated steatotic liver disease [MASLD]). Individuals with MetALD demonstrated a higher risk of all-cause (HR: 1.68, 95% CI: 1.10-2.57) and cancer-related mortality (HR: 2.40, 95% CI: 1.23-4.66). MASLD with advanced fibrosis had an increased risk of all-cause mortality compared to MASLD without advanced fibrosis.

CONCLUSIONS

SLD, especially MASLD and MetALD, is associated with increased all-cause mortality among adults in the US. Given this significant association between SLD or subtype of SLD (MASLD and MetALD) and all-cause mortality, adopting the proposed SLD criteria may help identify a sub-group of individuals with SLD who are at an increased risk for all-cause mortality.

Non-alcoholic fatty liver disease-related fibrosis and sarcopenia: An altered liver-muscle crosstalk leading to increased mortality risk

In the last few decades, the loss of skeletal muscle mass and function, known as sarcopenia, has significantly increased in prevalence, becoming a major global public health concern. On the other hand, the prevalence of non-alcoholic fatty liver disease (NAFLD) has also reached pandemic proportions, constituting the leading cause of hepatic fibrosis worldwide. Remarkably, while sarcopenia and NAFLD-related fibrosis are independently associated with all-cause mortality, the combination of both conditions entails a greater risk for all-cause and cardiac-specific mortality. Interestingly, both sarcopenia and NAFLD-related fibrosis share common pathophysiological pathways, including insulin resistance, chronic inflammation, hyperammonemia, alterations in the regulation of myokines, sex hormones and growth hormone/insulin-like growth factor-1 signaling, which may explain reciprocal connections between these two disorders. Additional contributing factors, such as the gut microbiome, may also play a role in this relationship. In skeletal muscle, phosphatidylinositol 3-kinase/Akt and myostatin signaling are the central anabolic and catabolic pathways, respectively, and the imbalance between them can lead to muscle wasting in patients with NAFLD-related fibrosis. In this review, we summarize the bidirectional influence between NAFLD-related fibrosis and sarcopenia, highlighting the main potential mechanisms involved in this complex crosstalk, and we discuss the synergistic effects of both conditions in overall and cardiovascular mortality.

Metabolic dysfunction-associated fatty liver disease is associated with increased all-cause mortality in the United States

BACKGROUND & AIMS

Recently, international experts proposed redefining non-alcoholic fatty liver disease (NAFLD) as metabolic dysfunction-associated fatty liver disease (MAFLD), based on modified criteria. It is suspected that outcomes such as mortality may differ for these clinical entities. We studied the impact of MAFLD and NAFLD on all-cause and cause-specific mortality in US adults.

METHODS

We analyzed data from 7,761 participants in the Third National Health and Nutrition Examination Survey and their linked mortality through 2015. NAFLD was diagnosed by ultrasonographic evidence of hepatic steatosis without other known liver diseases. MAFLD was defined based on the criteria proposed by an international expert panel. The Cox proportional hazard model was used to study all-cause mortality and cause-specific mortality between MAFLD and NAFLD, with adjustments for known risk factors.

RESULTS

During a median follow-up of 23 years, individuals with MAFLD had a 17% higher risk of all-cause mortality (hazard ratio [HR] 1.17; 95% CI 1.04-1.32). Furthermore, MAFLD was associated with a higher risk of cardiovascular mortality. NAFLD per se did not increase the risk of all-cause mortality. Individuals who met both definitions had a higher risk of all-cause mortality (HR 1.13, 95% CI 1.00-1.26), while individuals who met the definition for MAFLD but not NAFLD had a 1.7-fold higher risk of all-cause mortality (HR 1.66, 95% CI 1.19-2.32). Estimates for all-cause mortality were higher for those with advanced fibrosis and MAFLD than for those with advanced fibrosis and NAFLD.

CONCLUSIONS

In this US population-based study, MAFLD was associated with an increased risk of all-cause mortality, while NAFLD demonstrated no association with all-cause mortality after adjusting for metabolic risk factors.

LAY SUMMARY

Our findings provide further support for the idea that non-alcoholic fatty liver disease (NAFLD) is a part of a broader multi-system disease that also includes obesity, diabetes, high blood pressure, and high cholesterol. Therefore, re-defining NAFLD as metabolic dysfunction-associated fatty liver disease (MAFLD) may help improve our understanding of predictors that increase the risk of death.

Sarcopenia in nonalcoholic fatty liver disease and all-cause and cause-specific mortality in the United States

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) has been associated with sarcopenia. However, mortality in the setting of NAFLD-related sarcopenia remains undefined. We aim to determine the all-cause and cause-specific mortality from sarcopenia among adults with NAFLD in the USA.

METHODS

11 065 individuals in the Third National Health and Nutrition Examination Survey were studied and linked mortality through 2015 was analysed. NAFLD was diagnosed based on presence of ultrasonographic hepatic steatosis without other known liver diseases. Sarcopenia was defined as skeletal muscle index determined by bioelectrical impedance analysis. The Cox proportional hazard model was used to assess all-cause mortality and cause-specific mortality, and hazard ratio (HR) adjusted for known risk factors.

RESULTS

During a median follow-up of 23 years or more, sarcopenia was associated with increased all-cause mortality (HR 1.27, 95% confidence interval [CI] 1.11-1.44). Only in individuals with NAFLD, sarcopenia was associated with a higher risk for all-cause mortality, while this association was absent in those without NAFLD. Individuals with both sarcopenia and NAFLD had a higher risk for all-cause mortality (HR 1.28 95% CI 1.06-1.55) compared with those without sarcopenia and NAFLD. Furthermore, sarcopenia was associated with a higher risk for cancer- and diabetes-related mortality among those with NAFLD. This association was not noted in those without NAFLD.

CONCLUSION

In this nationally representative sample of US adults, sarcopenia was associated with a higher risk for all-cause, cancer- and diabetes-related mortality in individuals with NAFLD.