The association between non-alcoholic fatty liver disease and hepatic steatosis index with triglyceride-glucose index among Iranian adults of the Amol Cohort Study: a cross-sectional study

This study aimed to investigate the association between non-alcoholic fatty liver disease (NAFLD), the Hepatic Steatosis Index (HSI), a surrogate marker of hepatic steatosis, and the triglyceride-glucose (TyG) index in a large Iranian population. This cross-sectional study included 3,120 participants from the second phase of the Amol Cohort Study. Venous blood samples were collected after a 12-hour overnight fast, and NAFLD was diagnosed using abdominal ultrasonography. The associations between TyG index tertiles and continuous TyG values and NAFLD and HSI were evaluated using multivariable logistic regression models. Statistical analyses were performed using SPSS, whereas receiver operating characteristic (ROC) analysis, calibration, bootstrap validation, and DeLong tests were conducted using R. Compared with participants in the first tertile of the TyG index, those in the second and third tertiles had significantly higher odds of NAFLD and elevated HSI in both the crude and adjusted models. In the second tertile, the crude odds ratios (ORs) were 2.499 (95% confidence interval [CI]: 2.070–3.018; P < 0.001) for NAFLD and 2.333 (95% CI: 1.956–2.782; P < 0.001) for elevated HSI. After adjustment for potential confounders, the corresponding ORs were 1.749 (95% CI: 1.388–2.203; P < 0.001) and 1.701 (95% CI: 1.248–2.320; P = 0.001), respectively. In the highest tertile, the crude ORs were 6.067 (95% CI: 5.009–7.349; P < 0.001) for NAFLD and 4.723 (95% CI: 3.923–5.692; P < 0.001) for elevated HSI, whereas the adjusted ORs were 3.629 (95% CI: 2.864–4.598; P < 0.001) and 3.171 (95% CI: 2.276–4.419; P < 0.001), respectively. Receiver operating characteristic (ROC) curve analysis demonstrated that HSI had the greatest discriminatory ability for identifying NAFLD, followed by the anthropometric indices, whereas the TyG index showed moderate discriminatory performance. The findings of this study indicate a significant association between the TyG index and NAFLD-related markers, including HSI, in a large Iranian population. However, the TyG index demonstrated lower discriminatory ability than HSI and several anthropometric indices, suggesting that it should be considered a moderate rather than a superior predictor of NAFLD.