Nonlinear Relationship Between Triglyceride-to-High-Density Lipoprotein Cholesterol Ratio and Non-Alcoholic Fatty Liver Disease: A Secondary Retrospective Analysis Based on a Japanese Longitudinal Study.

Abstract

Background: The purpose of this research is to investigate the particular connection between the triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio and non-alcoholic fatty liver disease (NAFLD) to offer a more precise foundation for evaluating NAFLD risk.

Methods: This study involves a secondary analysis of a retrospective cohort study conducted from 2004 to 2015 in a Japanese population, which included 14,106 participants. The TG/HDL-C ratio was determined by the levels of triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C). Participants were grouped according to the quartiles of TG/HDL-C. We analyzed the relationship between TG/HDL-C and NAFLD using Cox proportional hazards regression, smooth curve fitting, and sensitivity analysis.

Results: The average age of the study participants was 43.51 ± 8.89 years, with 7275 (51.57%) being male. After considering potential confounding factors, the study found a positive correlation between TG/HDL-C and NAFLD (OR: 1.37, 95% CI: 1.31-1.43, p < 0.001). Moreover, a nonlinear relationship between TG/HDL-C and NAFLD was found, with a turning point at 1.42. The odds ratio (OR) on either side of this inflection point were 3.71 (95% CI: 2.87-4.79) on the left and 1.23 (95% CI: 1.17-1.29) on the right, indicating a stronger correlation when TG/HDL-C is below 1.42, particularly in younger individuals, females, and those with a BMI under 25 kg/m².

Conclusion: The TG/HDL-C index shows a nonlinear positive correlation with NAFLD risk, particularly when the TG/HDL-C ratio is below 1.42, with a stronger association observed in younger individuals, females, and lower-BMI populations.