AISI and MASLD: a nonlinear association in U.S. adults (NHANES 2017-2020)

Systemic inflammation is recognized as a key driver in the development of metabolic dysfunction-associated steatotic liver disease (MASLD). While emerging evidence suggests that the Aggregate Index of Systemic Inflammation (AISI) may reflect overall inflammatory burden, its association with MASLD prevalence remains poorly understood, especially in large population-based studies. This is a population-based, cross-sectional study analyzed NHANES data (2017-2020) from 5,948 U.S. adults aged $$\ge $$ 20 years, including both sexes and diverse ethnicities. We aimed to assess the association between the Aggregate Index of Systemic Inflammation (AISI) and MASLD prevalence. MASLD was defined by a controlled attenuation parameter (CAP) $$\ge $$ 274 dB/m, and participants with viral hepatitis or excessive alcohol intake were excluded. AISI was calculated from neutrophil, monocyte, platelet, and lymphocyte counts. We used adjusted analysis models to evaluate the association, adjusting for demographic and clinical covariates. Subgroup and sensitivity analyses were conducted to test the robustness of our findings. Our research identified a significant association between AISI and MASLD prevalence. After adjusting for confounders, individuals in the highest AISI quartile had a 53% higher risk of MASLD (OR = 1.53; 95% CI: 1.14-2.06; P for trend < 0.001). A nonlinear relationship was observed, with an inflection point at $$\log _2$$ AISI = 8.552. AISI is independently associated with MASLD prevalence in U.S. adults and may serve as an accessible biomarker for MASLD risk stratification in primary care settings.