Prognosis prediction by urinary liver-type fatty acid-binding protein in patients in the intensive care unit admitted from the emergency department: A single-center, historical cohort study

Abstract

Introduction: Early risk stratification of critically ill patients is essential for optimizing intensive care unit (ICU) resource allocation and treatment decisions. Urinary liver-type fatty acid-binding protein (L-FABP) is a simple, noninvasive biomarker that may provide real-time information on organ dysfunction. However, its prognostic utility in patients admitted to the ICU from the emergency department remains unclear. 
Aim of the study: The aim of this study was to evaluate the prognostic value of L-FABP levels measured shortly after ICU admission in predicting 28-day mortality among patients admitted from the emergency department.
Methods: This single-center retrospective observational study included patients admitted to the ICU between December 2020 and August 2022. Urinary L-FABP concentrations were measured at ICU admission (T0) and 3 hours later (T3). The primary outcome was 28-day in-hospital mortality. Prognostic performance was assessed using receiver operating characteristic curves and Cox proportional hazards models with inverse probability of treatment weighting. Results were compared with Acute Physiology and Chronic Health Evaluation (APACHE) II, Sequential Organ Failure Assessment (SOFA) scores, and lactate levels. 
Results: Data of 118 patients were included in the final analysis. Urinary L-FABP levels at T3 showed the highest AUC for predicting 28-day mortality (area under the curve [AUC] = 0.873), compared with APACHE II (AUC = 0.801), SOFA (AUC = 0.753), and the lactate level (AUC = 0.734). An elevated L-FABP (T3) level was independently associated with increased mortality (hazard ratio [HR] = 8.60, 95% confidence interval [CI]: 1.02–72.64, P = 0.047). The T3/T0 ratio showed only modest predictive value (AUC = 0.623). 
Conclusions: Urinary L-FABP levels measured 3 hours after ICU admission were an independent predictor of short-term mortality. The marker’s simplicity and bedside applicability suggest its potential utility not only in ICUs but also in emergency departments and triage decision-making.