Comparison of SII, NLR, and SIRI for severity stratification and prognosis in sepsis-related acute kidney injury

BACKGROUND: Sepsis-associated acute kidney injury (SA-AKI) is a severe complication linked to excessive systemic inflammation and immune dysregulation, with high mortality and poor prognosis. OBJECTIVE: To compare the predictive efficacy of the Systemic Immune-Inflammation Index (SII), Neutrophil-to-Lymphocyte Ratio (NLR), and Systemic Inflammation Response Index (SIRI) for adverse outcomes in SA-AKI patients. METHODS: This retrospective study included 265 SA-AKI patients admitted to the ICU (June 2022-June 2025). Patients were stratified by AKI severity and 28‑day outcomes. SII, NLR, and SIRI were calculated from admission bloodwork. Associations with 28‑day mortality were assessed using Spearman correlation, independent risk factors by logistic regression, and predictive performance by ROC curves. RESULTS: = 0.607). Logistic regression confirmed them as independent risk factors. The combined model achieved the highest AUC (0.943), with 89.51% sensitivity and 84.47% specificity, outperforming any single indicator. CONCLUSION: SII provides superior predictive value for 28‑day mortality in SA-AKI patients compared with NLR and SIRI. Combined testing further enhances predictive performance, supporting its potential as a cost‑effective bedside tool for risk stratification.