Predicting mortality in critically ill patients: a machine learning approach to electrolyte imbalances and clinical risk factors

BACKGROUND: Critically ill patients in intensive care units (ICUs) exhibit high mortality due to complex interactions among metabolic instability, organ dysfunction, and therapeutic interventions. While conventional severity scores like SOFA and APACHE II are widely used, they insufficiently integrate dynamic metabolic markers. METHODS: We performed a retrospective cohort study of 1,004 adult ICU patients. Demographic, clinical, and laboratory data were analyzed using multivariate logistic regression and machine learning algorithms (Random Forest, XGBoost). Model performance was assessed using AUC-ROC, calibration slope, and sensitivity at fixed specificity threshold. RESULTS: The ICU mortality was 30.7%. Independent predictors of mortality included SOFA score ≥ 8 (aOR = 4.0), mechanical ventilation (aOR = 3.1), hyperlactatemia ≥ 4 mmol/L (aOR = 2.6), vasopressor use (aOR = 2.7), and GCS ≤ 8 (aOR = 2.4). The XGBoost model achieved superior discrimination (AUC = 0.86; 95% CI: 0.83–0.89) compared to logistic regression (AUC = 0.84), SOFA (AUC = 0.72), and APACHE II (AUC = 0.75). A validated nomogram incorporating eight key predictors stratified mortality risk into four actionable tiers. Subgroup analysis confirmed robust performance across age strata, sepsis status, and AKI stages. CONCLUSIONS: Integrating metabolic markers with clinical severity scores enhances ICU mortality prediction. Our nomogram offers a practical, interpretable tool for bedside risk stratification and clinical decision support.