Prognostic Value of Standard Base Excess in Sepsis-Associated Acute Kidney Injury: A Retrospective Cohort Study.

Background: Standard base excess (SBE) is a pivotal indicator of metabolic acid-base status and has been associated with adverse outcomes in critically ill patients. Nevertheless, the evidence regarding its association with mortality risk in sepsis-associated acute kidney injury (SA-AKI) remains limited. Methods: The present study utilized the MIMIC-IV database and comprised 16,842 adult patients with SA-AKI. Patients were stratified into quartiles based on SBE levels. The association between SBE and 28-day and 180-day all-cause mortality was evaluated using Cox proportional hazards models. Restricted cubic spline analysis was performed to assess potential nonlinear relationships. Multivariable adjustments and subgroup analyses were conducted to ensure the robustness of the findings. Results: Multivariate Cox regression analysis demonstrated that patients in the higher SBE quartiles had significantly lower risks of 28-day and 180-day mortality compared to those in the lowest quartile. Kaplan-Meier survival curves and restricted cubic spline analysis further confirmed a significant association between SBE levels and mortality risk, with evidence of a nonlinear relationship. Subgroup analyses showed different interaction effects between the primary and secondary outcomes. Conclusions: SBE was associated with mortality risk in patients with SA-AKI, with lower levels of SBE being associated with worse outcomes. As a routine blood gas parameter, SBE may serve as a useful indicator for risk stratification and prognostic assessment in this population.