Association between triglyceride glucose-body mass index and all-cause mortality in critically ill patients with atherosclerotic cardiovascular diseases: a retrospective cohort study using the MIMIC-IV database

BACKGROUND: Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of cardiovascular mortality worldwide, with insulin resistance recognized as a key pathophysiological driver. While the triglyceride glucose-body mass index (TyG-BMI) has emerged as a promising insulin resistance marker, its prognostic value for ASCVD mortality outcomes requires further elucidation. METHODS: We conducted a retrospective cohort study of 1,637 critically ill ASCVD patients (median age 68.3 years) from the MIMIC-IV database. The primary endpoints were 30-day and 1-year mortality, with secondary assessments of 90-day and 180-day mortality. Comprehensive statistical analyses included multivariable Cox regression, restricted cubic splines (RCSs) for nonlinearity assessment, and Kaplan-Meier survival analysis. RESULTS: After full adjustment for potential confounders, elevated TyG-BMI showed significant inverse associations with both 30-day (HR 0.11, 95% CI 0.06-0.19) and 1-year mortality (HR 0.13, 95% CI 0.08-0.20). RCS analysis revealed a characteristic L-shaped dose-response relationship (nonlinear P < 0.001), while Kaplan-Meier curves demonstrated progressively improved survival across TyG-BMI quartiles (log-rank P < 0.001). CONCLUSION: This study revealed that the TyG-BMI is an independent predictor of mortality in critically ill ASCVD patients, with a distinct nonlinear protective effect. These findings support the potential clinical utility of the TyG-BMI for risk stratification in this high-risk population.