Association between triglyceride-glucose and triglyceride-glucose related indices with all-cause mortality in depression participants: a cohort study from NHANES

Abstract

Background: While the triglyceride-glucose (TyG) index and related indices have been recognized as markers of insulin resistance and cardiometabolic disorders, few studies have examined their association with all-cause mortality in individuals with depression. This study aimed to investigate the relationship between the TyG index, its related indices, and all-cause mortality among patients with depression in the United States.

Methods: A total of 3,179 patients with depression were identified from the National Health and Nutrition Examination Survey (NHANES, 2005-2018). Participants were categorized into tertiles (T1, T2, T3) based on the TyG index and its derived indices: TyG combined with body mass index (TyG-BMI), waist circumference (TyG-WC), and waist-to-height ratio (TyG-WHtR). Cox regression analysis and Kaplan-Meier curve analysis were used to explore the relationship between the independent variable TyG and its derived indicators and the dependent variable all-cause mortality.Curve fitting and threshold effect analyses were performed to evaluate potential nonlinear or dose-response relationships. Subgroup and sensitivity analyses were conducted to validate the robustness of the results.

Results: Over a 13-year follow-up period, both the lowest and highest tertiles of the TyG index and its related indices were associated with significantly increased risks of all-cause mortality compared to the middle tertile. Restricted cubic spline analysis revealed U-shaped nonlinear relationships between these indices and all-cause mortality, with distinct threshold effects. Among the indices, TyG-BMI and TyG-WC demonstrated the strongest associations, though similar trends were observed for the other TyG-related indices.

Conclusion: This study identified nonlinear associations between the TyG index and its related indices (TyG-BMI, TyG-WC, TyG-WHtR) and all-cause mortality in patients with depression, with clear threshold effects. These findings highlight the potential utility of stratified risk assessment and targeted interventions based on these thresholds.

Keywords: National Health and Nutrition Examination Survey (NHANES); all-cause mortality; depression; triglyceride glucose; triglyceride glucose body mass index; triglyceride glucose-waist circumference; triglyceride glucose-waist height ratio.

Figure 1

Flow chart of the study population inclusion. Flow chart of participants selection. NHANES, National Health and Nutrition Examination Survey; TyG, triglyceride-glucose; TyG-BMI, TyG with body mass index; TyG-WC, TyG with waist circumference; TyG-WHtR, TyG with waist-to-height ratio; PIR, poverty-income ratio.

Figure 2

Association between TyG and TyG related Indices with All-Cause Mortality risk in depression participants. TyG,triglyceride-glucose;TyG-BMI,TyG with body mass index;TyG-WC,TyG with waist circumference;TyG-WHtR, TyG with waist-to-height ratio,PIR,poverty-income ratio. Restricted cubic spline curve for the association of TyG-related indices with all-cause mortality. All-cause mortality for (A) TyG index, (B) TyG-BMI index, (C) TyG-WC index and (D) TyG-WHtR index. The solid red lines indicate hazard ratios (HRs), with the width of the red shaded areas representing the 95% confidence intervals (95% CIs). The light blue dashed line serves as the reference line, The intersection point of the reference line is the median by default. The light blue shaded bar areas in the background illustrate the population distribution of TyG-related indices. Adjusted for age, sex, race, marital status, PIR, education level, smoking status,drinking status, hyperlipidemia.

Figure 3

Subgroup analyses of TyG-related indices and all-cause mortality. TyG, triglyceride-glucose; TyG-BMI, TyG with body mass index; TyG-WC, TyG with waist circumference; TyG-WHtR, TyG with waist-to-height ratio, PIR, poverty-income ratio. HR, hazard ratio. Forest plots showing the association of TyG and TyG-related indices with the risk of all-cause mortality in depressed individuals. All-cause mortality for (A) TyG index, (B) TyG-BMI index, (C) TyG-WC index and (D) TyG-WHtR index. Adjusted for age, sex, race, marital status, PIR, education level, smoking status, drinking status, hyperlipidemia. Purple diamonds indicate point estimates of effect sizes, The length of the line segment indicates the 95% confidence interval of the effect size.