Association of the triglyceride-glucose index with all-cause and cardiovascular mortality among individuals with cardiovascular-kidney-metabolic syndrome: a population-based cohort study using data from the US National Health and Nutrition Examination Survey, 1999-2018.

Objective: The study investigated the association between the triglyceride-glucose (TyG) index (a surrogate measure for insulin resistance) and all-cause and cardiovascular disease (CVD) mortality among individuals with cardiovascular-kidney-metabolic syndrome.

Design: Population-based cohort study.

Setting: US National Health and Nutrition Examination Survey, 1999-2018.

Participants: A total of 13 585 participants who had valid data were included in this analysis.

Outcome measures: Data from the participants were linked to death certificates to obtain follow-up mortality information from the National Death Index. Cox proportional hazards models were used to assess the associations between the TyG index and all-cause and CVD mortality. Non-linear associations and threshold effects were investigated using restricted cubic spline regression and a two-piecewise Cox proportional hazards model.

Results: During a median follow-up of 99 months, a total of 2876 (16.24%) deaths occurred, of which 961 were attributed to CVD. Each one-unit increase in the TyG index was associated with an 8.9% relative increase in the hazard of all-cause mortality (HR 1.089, 95% CI 1.013 to 1.171) and a 19.5% relative increase in the hazard of CVD mortality (HR 1.195, 95% CI 1.027 to 1.390). Non-linear relationships were identified between the TyG index and all-cause and CVD mortality, with threshold values of 8.97 and 8.81 for all-cause and CVD mortality, respectively. A significant interaction effect was found between age and the TyG index.

Conclusion: There was a U-shaped relationship between the TyG index and both all-cause and CVD mortality. The thresholds of the TyG index may serve as potential tools for managing populations with cardiovascular-kidney-metabolic syndrome to reduce mortality risk.