The Lactate-to-Albumin Ratio Predicts Short and Long-Term Mortality in Patients with Traumatic Brain Injury: A Retrospective Cohort Study from the MIMIC-IV Database

Background Traumatic brain injury (TBI) exhibits significant prognostic heterogeneity, necessitating reliable early prognostic markers. The lactate-to-albumin ratio (LAR), a composite marker of tissue hypoxia and systemic inflammation, still needs to be validated as a prognostic indicator for TBI in a large-scale cohort. Methods This study utilized the MIMIC-IV database (V3.1) to enroll adult patients with traumatic brain injury (TBI) who were admitted to the ICU for the first time. The primary exposure variable was LAR within 24 hours of admission. The primary outcomes included all-cause mortality at 28 days, 90 days, and 365 days, as well as mortality during the ICU stay. Kaplan— Meier survival analysis compared survival differences across LAR quartiles. Univariate and multivariate Cox proportional hazards regression models assessed the association between LAR and mortality risk, yielding hazard ratios (HR) and 95% confidence intervals (CI). Restricted cubic spline (RCS) analysis evaluated the dose-response relationship between LAR and mortality. Subgroup analyses by age, sex, surgery, sepsis, hypertension, and diabetes further examined this association. Results In the multivariable-adjusted model (Model 5), patients in the Q4 group exhibited significantly elevated mortality risks compared to the Q1 group: ICU mortality (HR = 2.20, 95% CI: 1.09–4.42, P = 0.027), 28-day mortality (HR = 1.83, 95% CI: 1.16–2.89, P = 0.009), 90-day mortality (HR = 1.71, 95% CI: 1.15–2.54, P = 0.008), and 365-day mortality (HR = 1.77, 95% CI: 1.24–2.53, P = 0.002). Restricted cubic spline analysis demonstrated a linear positive correlation between LAR and mortality risk (P for nonlinearity > 0.05). Subgroup analysis revealed effect modification of the association between LAR and prognosis in patients with sepsis (P for interaction < 0.001). Conclusion LAR is an independent predictor of both short-term and long-term mortality in TBI patients. This readily obtainable metric facilitates early risk stratification.