Association between monocyte-to-lymphocyte ratio and metabolic dysfunction-associated steatotic liver disease and hepatic steatosis: evidence from NHANES 2017–2020

Background: The monocyte-to-lymphocyte ratio (MLR), an emerging inflammatory immune indicator, has an unclear association with metabolic dysfunction-associated steatotic liver disease (MASLD). This study aimed to evaluate the relationship between MLR and MASLD in the U.S. population and further explore its association with hepatic steatosis and liver fibrosis. Methods: This cross-sectional study analyzed data from 6,801 participants in the 2017-2020 National Health and Nutrition Examination Survey (NHANES). Multivariable logistic regression and multivariable linear regression were used to assess the associations of MLR levels with MASLD, hepatic steatosis [controlled attenuation parameter (CAP)], and liver fibrosis. Smooth curve fitting, restricted cubic spline (RCS) analysis, and threshold effect analysis were used to explore the relationship between MLR and MASLD. Subgroup analyses and interaction tests were conducted by sex, body mass index (BMI), race/ethnicity, and smoking status. Results: A total of 6,801 participants (mean age 48.61 years) were included in the analysis. After full adjustment for confounders, Ln(MLR) was significantly positively associated with MASLD risk [odds ratio (OR) =2.58, 95% confidence interval (CI): 1.99-3.35, P