Association between metabolic score of visceral fat and all-cause mortality among individuals with metabolic dysfunction-associated steatotic liver disease: a follow-up study based on NHANES III (1988-1994).

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease, seriously threatening the public health. However, the specific role of metabolic score of visceral fat (METS-VF) as a prognostic marker in the MASLD population remains unclear. In this study, we explored the association and nonlinear relationship between METS-VF and all-cause mortality among MASLD population.

Methods: This study included American adults aged over 20 years with MASLD who participated in the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994) in the United States. Kaplan-Meier curve was used to explore the relationship between different METS-VF levels and all-cause mortality. Multivariable Cox regression analysis was used to explore the independent linear relationship between METS-VF and all-cause mortality. In addition, Cox regression with restricted cubic spline functions and smooth curve fitting were used to evaluate potential nonlinear associations. An inflection point of METS-VF was determined using a two-piece Cox regression model.

Results: During an average follow-up period of 23.15 years, there were 1,413 all-cause deaths and the cumulative all-cause mortality proportion was 46.6%. Kaplan-Meier curve revealed that high METS-VF significantly increased the mortality risk in the MASLD population. Multivariate Cox regression analysis revealed that METS-VF was independently associated with all-cause mortality (hazard ratio [HR]: 1.121; 95% confidence interval [CI]: 1.103-1.139; P < 0.001). Cox regression with restricted cubic spline functions and smooth curve fitting showed a J-shaped relationship between METS-VF and all-cause mortality, with an inflection point of 6.394. The HR was 1.068 (95% CI: 1.038-1.099, P < 0.001) before the inflection point and 1.143 (95% CI: 1.122-1.166, P < 0.001) after it.

Conclusion: This study reveals that higher METS-VF levels are significantly associated with an increased risk of all-cause mortality in individuals with MASLD, characterized by a J-shaped non-linear relationship. This finding provides a new indicator for prognosis assessment in the MASLD population.