Association Between Thyroid Hormone Sensitivity Indices and Metabolic- Associated Fatty Liver disease: Development and Validation of Risk Prediction Model in Retrospective Cohort Study

Purpose This study aimed to assess the association between thyroid hormone sensitivity indices and metabolic-associated fatty liver disease (MAFLD) and to develop a predictive model for MAFLD based on these indices. Methods A total of 508 participants with normal thyroid function were retrospectively included, and randomly divided into a training group (n = 356) and a testing group (n = 152). The thyroid hormone sensitivity indices, including the Thyroid Feedback Quantile-based Index by FT ₃ (TFQI _FT3 ), FT ₄ (TFQI _FT4 ), and the free triiodothyronine to free thyroxine (FT ₃ / FT ₄ ) ratio, were calculated. Key variables were screened using LASSO regression, independent risk factors for MAFLD were found using multivariate logistic regression, and a visual nomogram prediction model was built. The receiver operating characteristic curve (ROC), calibration curve, and decision curve analysis (DCA) were used to validate the model's performance. Results Among 508 euthyroid individuals, 136 (26.77%) met diagnostic criteria for MAFLD. Multiple logistic regression analysis in the training cohort identified TSH, FT ₃ /FT ₄ , TFQI _FT3 , TFQI _FT4 , sex, body mass index, alanine aminotransferase, triglycerides and fasting blood glucose as predictors of MAFLD ( P  < 0.05). The central sensitivity index TFQI _FT3 was positively correlated with MAFLD risk (OR = 4.653, 95% CI: 1.071–21.881), while TFQI _FT4 was negatively correlated (OR = 0.059, 95% CI: 0.010–0.313). Based on the above results, a predictive nomogram for MAFLD risk was constructed. The nomogram model exhibited strong performance in both the training set (AUC = 0.830) and the testing set (AUC = 0.808), demonstrating excellent calibration curve fitting and significant clinical net benefit, as indicated by the DCA. Conclusions The thyroid hormone central sensitivity index (TFQI _FT3, TFQI _FT4 ) has independent predictive value for MAFLD risk. This study constructs an early screening and prediction model for MAFLD, providing new insights and directions for early diagnosis and treatment. Clinical trial number: Not applicable. Trial registration: Retrospectively registered.