The nonlineard association between triglyceride to HDL cholesterol ratio and long-term heart disease risk: findings from China Health and Retirement Longitudinal Study (CHARLS).

Objective: The aim of this study was to investigate the relationship between triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) and the risk of cardiovascular disease (CVD) in middle-aged and elderly Chinese population. CVD has high morbidity and mortality in China, with 5.09 million CVD deaths in 2019 and a mortality rate of 364.5 cases per 100,000 people. Existing studies have focused on specific populations and lack studies on the general population.

Methods: This study used data from the China Health and Aged Care Tracking Survey (CHARLS) to analyse the middle-aged and elderly population between 2011 and 2020. The exposure variable was TG/HDL-C ratio, the outcome variable was the occurrence of heart disease (including myocardial infarction, coronary heart disease, etc.), and the covariates included age, gender, education level, and body mass index. The final sample size was 4,551 participants. Weighted Cox regression models were used to assess the association between TG/HDL-C and CVD risk, and nonlinear associations and stratified analyses were performed.

Results: The results demonstrated a significant association between TG/HDL-C ratios and cardiac morbidity, with a risk ratio of 0.71 (95% CI: 0.71-0.71) in the adjusted model II. Nonlinear analysis revealed a threshold effect. Within the TG/HDL-C 0.15-1.5 interval (inflection point LnTG/HDL-C 0.41), each 1-unit increase in Ln (TG/HDL-C) was associated with a 17% reduction in the risk. The inflection point was associated with a 0.83-fold reduction in the risk of CVD (95% CI: 0.75, 0.92; p = 0.0003), but beyond this point, the association was no longer significant (1.00-fold reduction in risk; 95% CI: 0.95, 1.05; p = 0.9701). In contrast, stratified analyses demonstrated that the results were more applicable to women and those younger than 65 years.

Conclusion: In summary, the study found a significant inverse relationship between the triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio and the risk of cardiovascular disease in the middle-aged and elderly Chinese population, with a nonlinear threshold effect observed at a TG/HDL-C ratio of around 1.5.