Comparison of NAFLD, MAFLD and MASLD characteristics and mortality outcomes in United States adults

Following the classification of metabolic dysfunction-associated fatty liver disease (MAFLD), non-alcoholic fatty liver disease (NAFLD) has recently been redefined again as metabolic dysfunction-associated steatotic liver disease (MASLD). However, the distinctions in characteristics and mortality outcomes between NAFLD, MAFLD and MASLD remain unclear. We analysed data from 7519 participants in the third National Health and Nutrition Examination Surveys of United States (US) and their linked mortality until 2019. Survey weight-adjusted multivariable Cox proportional model was used to study the mortality over three terms. The prevalence of NAFLD, MAFLD and MASLD was 18.5%, 19.3% and 20.8%, respectively. Most individuals with NAFLD (94.5%) or MAFLD (100%) can be classified as MASLD, while a relatively low percentage of those with MASLD were also diagnosed with either NAFLD (84.1%) or MAFLD (92.7%). During a median follow-up of 26.9 years, both MAFLD and MASLD were associated with increased risk of all-cause mortality (adjusted hazard ratio [aHR] 1.18, 95% CI 1.04-1.33 and 1.19, 1.06-1.34, respectively), this association was mainly observed in NAFLD-/MASLD+ subgroups. NAFLD was not associated with all-cause mortality. However, all three terms were associated with an increased risk of all-cause mortality in individuals with advanced fibrosis (aHR: 1.71-1.81). Subgroup analyses showed that higher risk of all-cause mortality for both MAFLD and MASLD were observed among older adults (≥65 year), non-Hispanic whites and those without diabetes. Both MASLD and MALFD were linked to higher all-cause mortality risk, but MASLD identified a greater number of individuals compared to MAFLD.