Combined predictive value of triglyceride-glucose index and neutrophil-to-lymphocyte ratio for carotid plaque in a physical examination population: a cross-sectional study

Carotid atherosclerosis is a major precursor of ischemic stroke and adverse cardiovascular events. Conventional imaging and risk stratification tools are limited by cost, accessibility, or low predictive accuracy for subclinical disease. The triglyceride-glucose (TyG) index (a surrogate of insulin resistance) and the neutrophil-to-lymphocyte ratio (NLR) (a marker of systemic inflammation) are readily available biomarkers. However, their synergistic value for predicting carotid plaque remains unclear. This retrospective cross-sectional study enrolled 837 participants who underwent health examination and carotid ultrasound. Multivariate logistic regression was used to evaluate independent and combined associations of TyG index and NLR with carotid plaque. Restricted cubic spline models were applied to explore nonlinear dose-response relationships. Predictive performance was assessed using receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA). Carotid plaque was present in 328 (39.2%) participants. Plaque patients had significantly higher TyG index and NLR than non-plaque participants (both P < 0.001). In adjusted analysis, high NLR alone or combined with high TyG index was independently associated with elevated carotid plaque risk, whereas high TyG index alone was not. Nonlinear thresholds were identified: plaque risk rose sharply when TyG index > 9.0 or NLR > 2.0. The combined TyG + NLR model achieved an area under the ROC curve (AUC) of 0.914, with 85.1% sensitivity and 87.4% specificity, significantly outperforming either marker alone. The model showed excellent calibration and favorable clinical net benefit across a wide threshold range. Elevated NLR, alone or combined with high TyG index, is a strong risk factor for carotid plaque. The integrated TyG + NLR model provides a highly accurate, non-invasive, and cost-effective tool for early risk stratification of carotid atherosclerosis, supporting large-scale screening and timely intervention in clinical practice.