Prognostic nutritional index (PNI) and risk of non-alcoholic fatty liver disease and advanced liver fibrosis in US adults: Evidence from NHANES 2017-2020.

Objective: This study explored the potential association between the Prognostic Nutritional Index (PNI) and the incidence of non-alcoholic fatty liver disease (NAFLD) and advanced liver fibrosis (AF) in the adult population of the United States. Methods: Information on 6409 participants ≥18 years old was downloaded from the U.S. National Health and Nutrition Examination Survey (NHANES) from 2017 to 2020. Multivariate analysis was combined with demographic factors to assess the relationships between PNI, NAFLD, and AF. A restricted cubic spline (RCS) was used to characterise the nonlinear association between the PNI and NAFLD and AF. Results: Patients without NAFLD had substantially lower mean values for parameters such as age, lymphocyte count, neutrophil count, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammatory index (SII), total cholesterol, triglycerides, HbA1c, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) than patients with NAFLD. Interestingly, non-NAFLD patients showed a pronounced increase in serum albumin levels compared to their NAFLD counterparts. In the subset without AF, there were discernibly lower measures of NLR, age, AST, ALT, γ-glutamyl transferase, triglycerides, neutrophil count, and body mass index (BMI) than in patients with AF. It was evident that those without AF had markedly elevated mean albumin and PNI levels in comparison to AF-affected individuals. In the comprehensive multivariable framework, a direct correlation was observed between PNI and NAFLD (adjusted odds ratio[aOR] = 1.07, 95% confidence interval [CI]: 1.05-1.09; p < 0.001), whereas PNI and AF were inversely correlated (aOR = 0.92; 95% CI: 0.88-0.96; p < 0.001). Within the RCS model, a swift ascendancy was noted in the relationship between the PNI and NAFLD, peaking at approximately 52. Conversely, a non-linear inverse association was observed between PNI and AF. Conclusion: Our analytical results indicate that elevated PNI levels are positively associated with an increased risk of NAFLD, but inversely related to the risk of AF. For robust validation of these observations, further research is required.