Association Between Whole Blood Cell-Derived Inflammatory Markers and All-Cause Mortality in Patients with Sepsis-Associated Acute Kidney Injury: A Retrospective Study Based on the MIMIC-IV Database

Background Sepsis-associated acute kidney injury (SA-AKI) is a serious condition with a high mortality rate. Whole blood-derived inflammatory markers like the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI), are emerging prognostic indicators for various diseases. This study endeavors to unravel the link of these markers to all-cause mortality(ACM) in the SA-AKI population utilizing the MIMIC-IV database. Methods A retrospective cohort study was conducted on SA-AKI patients meeting the Sepsis-3 and KDIGO criteria. Cox regression analysis was performed to evaluate the association between inflammatory markers and mortality. Restricted cubic spline (RCS) analysis was employed to unveil the potential nonlinear relation of inflammatory markers to mortality. Survival differences across varying levels of inflammation were compared via Kaplan-Meier (KM) survival curves. Subgroup analyses were executed to examine the robustness of the relation and possible interactions between variables. The predictive performance of inflammatory markers was evaluated via receiver operating characteristic (ROC) curves, and the clinical utility of these markers was assessed through clinical decision curve analysis(DCA). Results 3429 SA-AKI patients were encompassed (2785 survivors at 30 days and 644 non-survivors). Cox regression analysis revealed a significant link between risen NLR, PLR, MLR, SII, and SIRI to elevated ACM. KM survival analysis demonstrated that patients with higher levels of inflammatory markers had notably higher 30-day death rates. Subgroup analysis indicated an interaction between coronary artery disease (CHD) and inflammation in influencing mortality risk. Among the markers assessed, NLR exhibited the highest forecasting accuracy for 30-day death (AUC = 0.624). Propensity score matching (PSM) confirmed the robustness of these findings. Conclusion Whole blood-derived inflammatory markers, particularly NLR, are closely linked to mortality in patients with SA-AKI. These markers may serve as valuable prognostic tools for identifying high-risk patients and improving clinical outcomes.