Lower Admission CALLY Index Is Associated with Contrast-Associated Acute Kidney Injury in Patients with STEMI Undergoing Primary PCI

Background and Objectives: The C-reactive protein–albumin–lymphocyte (CALLY) index integrates inflammatory, nutritional, and immune information, but its relationship with contrast-associated acute kidney injury (CA-AKI) in patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) remains uncertain. This study evaluated the association between admission CALLY and CA-AKI and compared its discriminatory performance with other inflammatory indices. Materials and Methods: This retrospective, single-center cohort included 903 patients with STEMI who underwent primary PCI between January 2018 and December 2024. CA-AKI was defined as an increase in serum creatinine of ≥0.3 mg/dL or ≥1.5-fold from baseline within 48–72 h after contrast exposure. Multivariable logistic regression assessed the independent association between CALLY and CA-AKI. Receiver operating characteristic analyses compared CALLY with the C-reactive protein-to-albumin ratio (CAR), C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), and systemic immune-inflammation index (SII). Results: CA-AKI occurred in 139 patients (15.4%). Median CALLY was lower in patients with than without CA-AKI (0.635 [IQR, 0.193–1.529] vs. 1.536 [IQR, 0.891–2.356]; p < 0.001). Each 50% decrease in CALLY was independently associated with higher odds of CA-AKI (adjusted OR, 1.587; 95% CI, 1.367–1.843; p < 0.001). CALLY yielded an AUC of 0.734 (95% CI, 0.683–0.782). Its discrimination was greater than that of CRP, NLR, and SII but was not significantly different from that of CAR (AUC, 0.707; DeLong p = 0.163). Conclusions: Lower admission CALLY was independently associated with CA-AKI and showed moderate discriminatory ability. Prospective multicenter studies are needed to validate these findings and establish clinical utility.