Prognostic value of non-insulin-based insulin resistance indices in patients with newly diagnosed coronary artery disease: a cohort study.

AIMS: : Insulin resistance (IR) plays a pivotal role in the onset and progression of coronary artery disease (CAD). This study aims to assess the efficacy and clinical utility of four non-insulin-based IR indices-Triglyceride-Glucose (TyG) index, Metabolic Score for Insulin Resistance (METS-IR), Triglyceride-Glucose-Body Mass Index (TyG-BMI), and Triglyceride to High-Density Lipoprotein Cholesterol ratio (TG/HDL-C)-in predicting prognosis in patients with newly diagnosed CAD. METHODS: This retrospective analysis included 890 patients with newly diagnosed CAD enrolled between January 2019 and June 2022. LASSO penalized regression was applied for covariate selection to mitigate overfitting (events-per-variable ratio ≈ 13.9), and Firth's penalized maximum likelihood estimation was performed as a sensitivity analysis. Multivariable Cox models and restricted cubic spline analyses examined associations between the four non-insulin-based IR indices and major adverse cardiovascular events (MACEs). The proportional hazards assumption was verified using Schoenfeld residual tests, and Bonferroni correction was applied for multiple comparisons (α = 0.0125). Receiver operating characteristic curves were plotted, and the incremental prognostic performance of each IR index for MACEs was assessed using the area under the ROC curve (AUC), C-statistics, net reclassification index (NRI), and integrated discrimination improvement (IDI). Kaplan-Meier analysis was used to evaluate the relationship between IR indices and clinical outcomes. RESULTS: Over a median follow-up of 26.5 months, the overall incidence of MACEs was 10.9%. TyG index (HR = 1.627, 95% CI: 1.228-2.145), TyG-BMI (HR = 1.019, 95% CI: 1.014-1.023), TG/HDL-C (HR = 1.127, 95% CI: 1.055-1.195), and METS-IR (HR = 1.104, 95% CI: 1.080-1.129) were all identified as independent risk factors for MACEs. METS-IR showed the highest incremental prognostic value (C-statistic = 0.779, IDI = 0.082, NRI = 0.356, P < 0.001). Log-rank tests indicated significantly higher MACEs rates in patients with higher IR indices (P < 0.01). CONCLUSIONS: TyG index, TyG-BMI, TG/HDL-C ratio, and METS-IR are independently associated with MACEs in patients with newly diagnosed CAD, with METS-IR demonstrating the highest incremental predictive performance.