An Explainable Leakage-Audited Framework for Multi-Horizon Sepsis-3 Onset Forecasting from Complex ICU Dynamics
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Keywords

Explainable AI
SHAP
Sepsis-3
MIMIC-IV
Dynamic landmark forecasting

How to Cite

An Explainable Leakage-Audited Framework for Multi-Horizon Sepsis-3 Onset Forecasting from Complex ICU Dynamics. (2026). Chaos and Fractals, 3(2), 76-91. https://doi.org/10.69882/adba.chf.2026072

Abstract

Sepsis-3 onset forecasting remains challenging because event prevalence is low at each patient-time landmark and retrospective electronic health record (EHR) models may inadvertently exploit workflow signals that reflect clinician suspicion rather than underlying patient physiology. We present an explainable, leakage-audited, multi-horizon LightGBM framework for physiology-based Sepsis-3 onset forecasting using MIMIC-IV v3.1. Adult first ICU stays with at least 8 hours of observation were transformed into hourly physiologic trajectories, Sepsis-3 onset labels, and repeated landmark prediction examples. Separate models estimated the probability of Sepsis-3 onset within the next 4, 6, 12, and 24 hours. The final cohort comprised 64,363 ICU stays, including 42,291 forecastable stays and 6,431 forecastable Sepsis-3 cases. The deployment-oriented no-admission-year CLEAN model achieved held-out AUROCs of 0.782, 0.772, 0.750, and 0.720 for the 4-, 6-, 12-, and 24-hour prediction horizons, respectively, with patient-level bootstrap 95% confidence intervals of 0.763–0.801, 0.752–0.792, 0.729–0.769, and 0.699–0.742. A paired leakage audit demonstrated that removing vasopressor exposure, measurement-age channels, and observation-mask channels resulted in AUROC changes of less than 0.01, indicating that predictive performance was primarily driven by physiologic information rather than workflow-related artifacts. Temporal validation on the latest deidentified admission-year group yielded a 6-hour AUROC of 0.762. At the 6-hour horizon, a top-2% no-year alarm policy with a 6-hour cooldown detected 17.8% of sepsis cases within 0–6 hours, 29.3% within 0–24 hours, and 40.3% before onset overall while generating 15.5 alerts per 100 patient-days. SHAP-based explainability analyses consistently identified neurologic status, temperature, urine-output dynamics, renal markers, inflammatory variables, vital signs, and lactate-related dynamics as the dominant predictors across forecasting horizons. These findings provide a robust and explainable physiology-based framework for future studies on Sepsis-3 onset forecasting in complex critical-care systems.

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