The relationship between the triglyceride-glucose (TyG) index and all-cause mortality in ICU patients with primary hypertension: a retrospective study

Abstract Background Hypertension includes both primary hypertension and secondary hypertension. Primary hypertension is the most common type of hypertension, accounting for 90% to 95% of all cases, with a complex and not fully understood pathogenesis. Insulin resistance (IR) is a metabolic abnormality that has been shown to be quite prevalent among patients with hypertension in existing literature. The triglyceride-glucose index (TyG-i) is a reliable indicator for assessing insulin resistance (IR). This study aims to evaluate the relationship between the TyG index at admission and all-cause mortality (ACM) in patients with severe primary hypertension, and to explore its role in predicting the future all-cause mortality risk in primary hypertension patients. Methods This study employs a retrospective design to categorize all patients into four quartiles based on the TyG index. The Kaplan-Meier (K-M) method was utilized to estimate the survival curves for each group and to compare the survival outcomes across different quartiles. To assess the nonlinear relationship between the TyG index and prognosis, Cox proportional hazards regression models and restricted cubic splines (RCS) were applied, adjusting for potential confounders. Additionally, subgroup analyses were performed to conduct stratified analyses and interaction tests. Results The study included 3,829 patients with a mean age of 69±11 years. Kaplan-Meier survival curve analysis showed that patients with higher TyG index levels had higher all-cause mortality rates at 30 days, 60 days, and 90 days post-admission. This indicates that a higher TyG index is associated with an increased risk of death in the short term. Additionally, multivariate Cox proportional hazards regression analysis revealed that an increased TyG index was significantly associated with all-cause mortality at 30 days, 60 days, and 90 days(HR: 1.93, 95% CI: 1.44-2.57, P-value: <0.001; HR: 1.80, 95% CI: 1.38-2.34, P-value: <0.001; HR: 1.72, 95% CI: 1.34-2.21, P-value: <0.001).Meanwhile, restricted cubic splines (RCS) analysis revealed a J-shaped relationship between the TyG index and all-cause mortality. This relationship suggests that as the TyG index level increases, the risk of all-cause mortality also progressively rises. Conclusion In summary, among patients with primary hypertension in the intensive care unit, elevated triglyceride-glucose index (TyG-i) levels are associated with an increased risk of short-term mortality.