Association of the Preoperative CALLY Index with Acute Kidney Injury After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: A Comparison with Other Inflammatory and Immune-Nutritional Indices

Background/Objectives: Acute kidney injury (AKI) is a frequent complication following cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). The association between preoperative inflammatory and immune-nutritional indices and postoperative AKI after CRS-HIPEC remains unclear. We aimed to investigate whether these prespecified candidate preoperative markers are associated with postoperative AKI in patients undergoing CRS-HIPEC. Methods: This retrospective single-center study included 87 patients who underwent CRS-HIPEC between October 2022 and April 2025. All received intraoperative cisplatin and mitomycin C. AKI was defined according to Kidney Disease: Improving Global Outcomes serum creatinine criteria. Preoperative neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune-inflammation index, pan-immune-inflammation value, systemic inflammation response index, and C-reactive protein–albumin–lymphocyte (CALLY) index were calculated from routine laboratory parameters. Each candidate marker was evaluated in a separate model adjusted for age and sex, and then in a second model additionally adjusted for baseline estimated glomerular filtration rate. Discriminatory performance was assessed using receiver operating characteristic analysis. The CALLY index was calculated using albumin in g/dL, lymphocyte count in ×109/L, and C-reactive protein in mg/L. Results: AKI developed in 24 patients (27.6%). In-hospital mortality was higher in patients with AKI than in those without AKI (25.0% vs. 1.6%; p = 0.002). A higher log10-transformed CALLY index remained associated with lower odds of AKI after adjustment for age and sex (adjusted OR, 0.276; 95% CI, 0.113–0.673; p = 0.005). The CALLY index had the numerically highest AUC among the evaluated indices, with moderate discriminatory performance (AUC, 0.708; 95% CI, 0.579–0.836). A data-derived exploratory cutoff of ≤1.640 yielded 79.2% sensitivity and 63.5% specificity. Conclusions: In this selected retrospective cohort of patients without established chronic kidney disease, a lower preoperative CALLY index was associated with postoperative AKI and showed moderate discrimination as an individual marker. The data-derived threshold should be considered exploratory and requires independent validation before clinical application.