The association between triglyceride-glucose index and all-cause mortality in postmenopausal women: A cohort study from NHANES
Elevated triglyceride–glucose (TyG) index has been linked to cardiovascular risk and metabolic disorders, but its relationship with all-cause mortality in postmenopausal women remains unclear. We aimed to investigate the association between baseline TyG index and all-cause mortality among postmenopausal women, and to determine whether a nonlinear (threshold) relationship exists. We conducted a prospective cohort study using data from the U.S. National Health and Nutrition Examination Survey 2001–2014. Participants were 3925 postmenopausal women (weighted mean age 63.1 years). Fasting subsample survey weights were applied, and the complex multistage sampling design (stratification and clustering) was fully accounted for in all analyses. TyG index was calculated from fasting triglyceride and glucose measurements. The main outcome was all-cause mortality. We used restricted cubic splines and design-based two-piecewise Cox proportional hazards regression to model nonlinear associations and identify a potential threshold. Over a median follow-up of approximately 9.9 years, 1088 deaths occurred (27.7% of participants). The association was nonlinear: the two-piecewise Cox analysis identified a significant threshold at TyG = 9.06 (95% confidence interval [CI] 8.92–9.26). Below the threshold, TyG index was not significantly associated with mortality (hazard ratio 0.88, 95% CI 0.69–1.11). Above this threshold, each 1-unit increase in TyG was associated with a 44% higher risk of all-cause mortality (hazard ratio 1.44, 95% CI 1.05–1.96, P = .020) after full adjustment for covariates. In this cohort of U.S. postmenopausal women, an elevated TyG index above 9.06 was associated with increased all-cause mortality. The relationship was nonlinear, with a risk threshold. This threshold should be considered exploratory and requires external validation before clinical use.