Associations of the triglyceride–glucose index, triglyceride glucose–body mass index and waist–triglyceride index with mortality in patients with cardiovascular–kidney–metabolic syndrome stages 0-4: evidence from NHANES 1999-2020

Background Cardiovascular–Kidney–Metabolic (CKM) syndrome is a major public health concern today, with insulin resistance (IR) serving as a key driver. Furthermore, the triglyceride–glucose index (TyG), TyG–body mass index (TyG–BMI) and waist–triglyceride index (WTI), which are useful biomarkers for assessing IR and obesity status, are associated with all-cause, cardiovascular disease (CVD) and diabetes mellitus (DM) mortality risk. However, the associations between these indices and mortality risk in patients with CKM syndrome stages 0–4 remain unclear. Methods In our retrospective cohort investigation, information was gathered from 10,622 individuals in the National Health and Nutrition Examination Survey (NHANES) during 1999–2020. The TyG, TyG–BMI, and WTI indices were calculated. To analyze the relationships between the TyG, TyG–BMI, and WTI indices and mortality in adults with CKM syndrome, several statistical methods were used. Kaplan–Meier curves were generated, followed by weighted univariate and multivariate Cox regression models. Additionally, additive Cox proportional hazards models were applied to further assess these associations. Demographic-based risk assessments were performed through stratified analysis. To better understand variations in risk across demographic subgroups, stratified statistical methods were employed. Results The incidence of CKM increased with increasing TyG index. Multivariate regression studies revealed that the TyG index was notably positively correlated with all-cause (HR: 1.12, 95% CI 1.01–1.24) and DM mortality (HR: 1.72, 95% CI 1.32–2.25). However, no significant correlation between the TyG index and CVD mortality was observed. Both the TyG–BMI and the WTI were significantly associated with DM mortality but not with all-cause or CVD mortality. A J-shaped link emerged between the TyG index and both all-cause and CVD mortality in CKM syndrome patients at stages 0–4 (nonlinear P value < 0.05). Stratified analysis revealed that the TyG index was strongly related to all-cause mortality in male hypertensive DM patients younger than 60 years and with CVD mortality in female hypertensive DM patients under 60 years of age ( P value < 0.05). Conclusion Compared with the TyG–BMI and WTI, the TyG index demonstrated a stronger correlation with elevated risks of all-cause, CVD and DM mortality among U.S. adults with CKM syndrome stages 0–4, and was more valuable for predicting mortality, particularly in those aged less than 60 years.