Predicting Contrast-Induced Nephropathy in NSTEMI: The Role of the HALP Score

<i>Background and Objectives:</i> Contrast-induced nephropathy (CIN) remains a significant complication following invasive coronary procedures. The HALP score-a composite index derived from hemoglobin, albumin, lymphocyte, and platelet counts-reflects nutritional and inflammatory status and may serve as a predictive biomarker for CIN. The aim of our study is to evaluate the relationship between the HALP score and the development of CIN in non-ST segment elevation myocardial infarction (NSTEMI) patients undergoing coronary angiography (CAG) or percutaneous coronary intervention (PCI). <i>Materials and Methods:</i> This retrospective study included 577 NSTEMI patients who underwent CAG or PCI between December 2022 and June 2025. Patients were divided into two groups based on CIN development. The HALP score was calculated and compared between groups. <i>Results:</i> Of the 577 NSTEMI patients included, 74 (12.8%) developed CIN. Patients who developed CIN were significantly older and had a higher prevalence of diabetes mellitus (DM), worse baseline renal function, and lower levels of hemoglobin, albumin, HDL cholesterol, and lymphocytes (<i>p</i> < 0.001). They also showed higher neutrophil counts, troponin-T levels, and received greater volumes of contrast media (CM). Oral antidiabetic drug (OAD) use was positively associated with CIN, while angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker use showed a negative association in univariate analysis. The HALP score was significantly lower in the CIN (+) group than CIN (-) group (15.88 ± 28.48 vs. 53.86 ± 28.48, <i>p</i> < 0.001). Multivariate analysis identified older age, DM, reduced left ventricular ejection fraction, elevated creatinine, increased neutrophils, lower hemoglobin, albumin, and lymphocytes, and higher CM volume as independent predictors of CIN. The HALP score remained a strong inverse predictor of CIN (OR: 0.895; 95% CI: 0.865-0.924; <i>p</i> < 0.001) and the Mehran score was positively associated with CIN risk (OR: 1.578; 95% CI: 1.154-2.087; <i>p</i> < 0.001). Covariate-adjusted receiver operating characteristic (AROC) analysis demonstrated that the HALP score showed good predictive accuracy (AUC: 0.780), with 74.3% sensitivity and 83.3% specificity at a cutoff of 24.1. <i>Conclusions:</i> The HALP score is a simple, accessible, and cost-effective biomarker with strong predictive value for CIN in NSTEMI patients undergoing invasive coronary procedures.