Background Lactate is an established prognostic marker in sepsis, but the additional predictive value of standard base excess (SBE) and alactic base excess (aBE) remains unclear. This study aimed to evaluate the prognostic utility of lactate, SBE, and aBE in predicting mortality among patients with sepsis and septic shock.

Methods This retrospective cohort study included 218 adult patients admitted to the intensive care unit (ICU) with a diagnosis of sepsis or septic shock. Arterial blood gas parameters (lactate, SBE, and calculated aBE), severity scores (APACHE II, SOFA), and clinical outcomes were recorded. Patients were stratified into survivors and non-survivors. Receiver operating characteristic (ROC) curve analysis and multivariate logistic regression were used to assess the prognostic accuracy of the biomarkers.

Results Among 218 patients, 128 (58.7%) were non-survivors. Non-survivors had significantly higher lactate levels (median: 2.9 mmol/L vs. 1.2 mmol/L; p < 0.001). Lactate remained an independent predictor of mortality (OR: 1.40, 95% CI: 1.11–1.77; p = 0.005). SBE showed limited prognostic value and lost significance in multivariate analysis. aBE did not differ significantly between groups and was not associated with mortality. ROC analysis showed lactate had the highest area under the curve (AUC: 0.742), while SBE (AUC: 0.421) was a poor predictor.

Conclusions Lactate is a superior independent predictor of ICU mortality in sepsis and septic shock. Neither SBE nor aBE provided additional prognostic value. These findings support the continued use of lactate for risk stratification, while highlighting the limited utility of SBE and aBE in this context.

The authors have declared no competing interest.

This study did not receive any funding

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The study protocol was approved by the Ethics Committee of Ondokuz Mayis University Faculty of Medicine, Samsun, Turkey (Approval No: 2024000579).

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The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.