Association of the C-Reactive Protein–Triglyceride–Glucose Index with Kidney Injury in Patients with Coronary Heart Disease: A Two-Center Cross-Sectional Study

Mengmeng Fan,1 Xueping Zhang,1 Xianwei Tian,1 Keli Li,2 Zhiqiang Liu11Department of Cardiology, Xinxiang Central Hospital, Xinxiang, Henan, People’s Republic of China; 2Department of Cardiology, Huangshan City People’s Hospital, Huangshan, Anhui, People’s Republic of ChinaCorrespondence: Zhiqiang Liu, Department of Cardiology, Xinxiang Central Hospital, Xinxiang, Henan, People’s Republic of China, Email ljlzq2001@126.comBackground: The composite index of inflammation and insulin resistance (IR), the C-reactive protein (CRP)–triglyceride–glucose (TyG) index (CTI), has been suggested to be closely associated with cardiovascular disease. However, the relationship between the CTI and kidney injury (KI), including its subtypes [declined kidney function (DKF) and proteinuria], remains unclear in patients with coronary heart disease (CHD), and whether sex differences exist is unknown.Methods: This two-center cross-sectional study enrolled 3793 patients with CHD between September 2021 and May 2026. Multivariable stepwise-adjusted logistic regression assessed associations of the CTI with KI and its subtypes. Restricted cubic spline (RCS) analysis identified dose-response relationships and threshold effects, followed by piecewise comparisons. Subgroup analyses stratified by sex were performed to evaluate consistency across sexes. The area under the receiver operating characteristic curve (AUC), decision curve analysis (DCA), and the Boruta algorithm compared the discriminative performance of the CTI versus CRP and TyG alone for KI and its subtypes.Results: Multivariable logistic regression showed that the CTI was significantly associated with KI and its subtypes in CHD patients. The overall prevalence of KI was 814/3,793 (21.5%). RCS revealed that CTI exceeding 4.8, 4.7, and 4.55, respectively, significantly increased risks of KI, DKF, and proteinuria. Notably, the increased risk of KI was particularly evident when CTI exceeded 4.45 in females and 4.96 in males. AUC, DCA, and Boruta rankings all confirmed stronger discriminative performance of the CTI than CRP or TyG alone for KI and its subtypes.Conclusion: Elevated CTI was independently associated with KI and its subtypes in CHD patients, with clear threshold effects that differed by sex and superior discriminative performance to single indicators. These associations were more pronounced in overweight/obese patients. Although CTI may help identify individuals at higher risk, the sex-specific thresholds should be regarded as exploratory threshold estimates and require external validation before clinical application.Keywords: coronary heart disease, C-reactive protein-triglyceride-glucose index, kidney injury, declined kidney function, proteinuria