Association of triglyceride glucose index with all-cause and cause-specific mortality among middle age and elderly US population

AIMS: To investigate the association between the triglyceride glucose (TyG) index and all-cause and cause-specific mortality in middle age and elderly population. METHODS AND RESULTS: A total of 9,254 participants with age ≥ 45 years were enrolled from the National Health and Nutrition Examination Survey cycle of 1999–2014. The TyG index was determined as ln [fasting triglycerides (mg/dL) x fasting glucose (mg/dL)/2]. Primary outcomes were all-cause mortality and cause-specific mortality (cardiovascular diseases and malignant neoplasms). The association between the levels of TyG and the risk of mortality was explored with Cox regression models. After a median follow-up of 7.6 years, 1,774 all-cause death occurred. Univariate analysis showed that the TyG was associated with all-cause mortality (hazard ratio [HR] 1.18, 95% confidence interval [CI] [1.11,1.26]; p < 0.001). Furthermore, multivariate-adjusted analysis found that the third TyG quartile (8.72 ~ 9.16) was associated with the lowest risk of all-cause mortality (HR 0.84, 95%CI [0.73, 0.98]; p < 0.05). Restricted cubic splines showed that the association between levels of TyG index and the risk of all-cause mortality was non-linear (p for nonlinearity < 0.001) and the inflection point was 9.18 using threshold effect analysis. The HR was 0.82 (95%CI [0.71,0.96]) below 9.18 while the HR was 1.32 (95%CI [1.12,1.55]) above 9.18. CONCLUSION: TyG index was U-shaped associated with all-cause mortality and the TyG index associated with the lowest risk of all-cause mortality was 9.18.