Association of triglyceride-glucose index and high-sensitivity C-reactive protein with contrast-induced nephropathy after percutaneous coronary intervention in patients with acute coronary syndrome: a retrospective cohort study

Background Contrast-induced nephropathy (CIN) remains a frequent and serious complication after percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) patients. The triglyceride-glucose (TyG) index, a marker of insulin resistance, and high-sensitivity C-reactive protein (hs-CRP), an inflammatory biomarker, may contribute to CIN development. Methods This retrospective cohort study included 1,818 ACS patients undergoing PCI between 2017 and 2024. Logistic regression, restricted cubic splines (RCS), and interaction analyses were performed to examine the nonlinear relationships and additive effects of TyG index and hs-CRP on CIN risk. Results Multivariate logistic regression analysis indicated that both the TyG index (OR = 4 .08, 95% CI: 2.95–5.71) and hs-CRP levels (OR = 1 .07, 95% CI: 1.05–1.10) were significant independent risk factors for CIN (all P < 0.001). The RCS analysis revealed nonlinear associations between the TyG index, hs-CRP, and CIN risk ( P < 0.001). Threshold effect analysis identified optimal cutoff values of TyG index ≥8.5 and hs-CRP ≥5.0 mg/L, beyond which CIN risk sharply increased. Patients with both TyG index ≥8.5 and hs-CRP ≥5.0 mg/L showed the highest CIN risk (adjusted OR = 8 .356, 95% CI: 2.13–32.8), with significant additive interactions observed (RERI = 4.914, A P = 0.588, SI = 3.012). The predictive model demonstrated a robust area under the ROC curve (AUC = 0.780, 95% CI: 0.750–0.809), with sensitivity of 77.7% and specificity of 69.3%. Conclusion Elevated TyG index and hs-CRP levels independently and synergistically increase CIN risk in ACS patients after PCI. These findings highlight the interplay between metabolic and inflammatory pathways in CIN pathogenesis and may help identify high-risk individuals for early preventive strategies.