Association of the RDW-to-albumin ratio with MAFLD and hepatic fibrosis in the U.S. population: a national cross-sectional study

Systemic inflammation plays a key role in the pathogenesis of metabolic dysfunction-associated fatty liver disease (MAFLD). The red blood cell distribution width (RDW) and serum albumin levels are well-recognized biomarkers reflecting inflammatory and nutritional status. This study systematically investigates the association between the RDW-to-albumin ratio (RAR) and MAFLD, while further analyzing the dose-response relationship between RAR and the severity of hepatic steatosis (assessed by Controlled Attenuation Parameter, CAP) and fibrosis (assessed by Liver Stiffness Measurement, LSM). This cross-sectional analysis was based on data from the National Health and Nutrition Examination Survey (NHANES) 2017-2020. MAFLD was diagnosed in accordance with the 2020 global consensus, combining evidence of hepatic steatosis (via (CAP ≥ 248 dB/m detected by Vibration-Controlled Transient Elastography [VCTE] or ultrasound) and metabolic dysfunction. Multivariate weighted logistic regression models were used to analyze the association between RAR and MAFLD. Restricted Cubic Spline (RCS) analysis was employed to evaluate the dose-response relationships between RAR and CAP, as well as(LSM). Among the 4,453 participants, 2,482 were diagnosed with MAFLD. After full adjustment for confounding factors, each 1-unit increase in RAR was associated with a 69% higher prevalence of MAFLD (OR = 1.69, 95% CI: 1.24-2.31). When RAR was categorized into tertiles, compared with the lowest tertile (RAR < 3.10), the highest tertile (RAR > 3.40) was associated with a 66% increased prevalence of MAFLD (OR = 1.66, 95% CI: 1.09-2.53). RCS analysis revealed a significant linear dose-response relationship between RAR and MAFLD prevalence (P-overall < 0.001, P-nonlinear = 0.09), and significant nonlinear dose-response relationships between RAR and CAP (P-overall < 0.01, P-nonlinear = 0.004) as well as LSM (P-overall < 0.01, P-nonlinear = 0.05). CAP and LSM values increased significantly with elevated RAR. RAR is significantly positively associated with MAFLD prevalence in a linear manner among the U.S. population, and is closely correlated with the severity of hepatic steatosis and fibrosis.