Data Sheet 1_Association and discriminative value of insulin resistance surrogate markers for aortic stiffness in asymptomatic adults.docx

Restricted cubic spline regression assessed potential nonlinear associations. Incremental discrimination was evaluated using ΔAUC, NRI, and IDI. Six machine-learning models were compared, and the most interpretable model was evaluated in an independent institutional validation cohort.</p>Results<p>Aortic stiffness was present in 32.8% (150/457) of the modeling cohort.

After full adjustment, the TyG index was independently associated with aortic stiffness (per-SD OR = 3.44, P = 0.002), as were TG/HDL-C (OR = 3.11, P = 0.039) and, more weakly, TyG-BMI (OR = 1.52, P = 0.043). The model including TyG showed higher discrimination (ΔAUC = 0.014, DeLong P = 0.025) and reclassification (continuous NRI = 0.692 and IDI = 0.041; both P < 0.001) than the base model. A data-derived TyG cutoff of 8.68 was identified as a potential marker for exploratory risk stratification.

The five-variable model, comprising age, MAP, diabetes mellitus, smoking, and TyG, yielded AUCs of 0.931 in the modeling cohort and 0.909 in the external validation cohort. Subgroup and sensitivity analyses showed similar patterns.</p>Conclusion<p>Among the three surrogate markers, the TyG index showed the strongest adjusted association with aortic stiffness and the greatest incremental discrimination beyond conventional clinical variables.

The five-variable model showed good discrimination in an independent institutional validation cohort. However, these cross-sectional findings support only potential risk-stratification value and do not establish temporal sequence, causality, or clinical utility; prospective studies are required to assess broader generalizability.</p>