Alactic Base Excess as a Predictor of Mortality in Trauma ICU Patients: Retrospective Study and Evaluation of Integration into Trauma Scoring Systems

Risk stratification in severe trauma remains a major clinical challenge: standard trauma scores (Injury Severity Score, ISS; Trauma and Injury Severity Score, TRISS) rely on anatomical and physiological data but lack metabolic components, potentially underestimating risk in haemodynamically compensated patients with underlying derangements. Alactic base excess (ABE) isolates the non-lactic fraction of metabolic acidosis by correcting base excess for lactate. We conducted a retrospective cohort study using the MIMIC-IV v3.1 database, including adult trauma patients with an ISS ≥ 16 and an arterial blood gas measurement within two hours of admission (n = 134), to assess ABE’s independent and incremental prognostic value for in-hospital and 30-day mortality, handling missing covariates by multiple imputation (m = 20). ABE was independently associated with in-hospital mortality after adjustment for age, New ISS (NISS), and mechanism of injury (odds ratio 0.84; 95% CI 0.745–0.946; p = 0.004; AUC 0.643), but its prognostic content overlapped substantially with lactate, and its incremental value beyond a clinical base model and beyond TRISS was small and statistically fragile; decision curve analysis showed no consistent net benefit from adding ABE to TRISS. The findings were consistent for 30-day mortality and stronger in a 60 min sensitivity cohort (n = 54; AUC 0.803), though this small subgroup may reflect selection effects. ABE should not be regarded as evidence of a novel physiological pathway in this trauma cohort; its practical contribution, if any, lies in immediate availability from a routine blood gas before ISS or TRISS can typically be computed. These findings are hypothesis-generating, given the single-centre design and absence of external validation, and require prospective, multicentre confirmation before clinical application.