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Machine learning for risk stratification in the emergency department (MARS-ED): a randomized controlled trial.
Paul M E L van Dam1, William P T M van Doorn2, Lotte Sevenich3
1Department of Internal Medicine, Division of General Internal Medicine, Section Acute Medicine, Maastricht University Medical Center +, Maastricht, Netherlands. paul.van.dam@mumc.nl.
A new machine learning tool, RISK INDEX, accurately predicts 31-day mortality using lab values. However, its prognostic accuracy did not translate into improved clinical decisions or outcomes in the emergency department.
Area of Science:
- Emergency medicine
- Clinical informatics
- Health services research
Background:
- Emergency department (ED) crowding requires efficient risk stratification.
- Existing tools (NEWS, APACHE II, SOFA) have limitations in generalizability and data requirements.
- Machine learning offers potential for improved predictive accuracy using routine data.
Purpose of the Study:
- To develop and evaluate the RISK INDEX, a machine learning tool predicting 31-day mortality using laboratory values, age, and sex.
- To assess the clinical impact and prognostic accuracy of the RISK INDEX compared to standard care and traditional scoring systems.
- To determine if enhanced prognostic accuracy translates into improved clinical decision-making and patient outcomes in the ED.
Main Methods:
- An investigator-initiated, open-label, randomized non-inferiority trial (MARS-ED) was conducted at a university medical center ED.
- Adult patients (≥18 years) with ≥4 laboratory tests were randomized (1:1) to standard care or standard care plus access to the RISK INDEX.
- Primary outcomes included prognostic accuracy for 31-day mortality and clinical impact, assessed via area under the receiver operating characteristic curve (AUROC) and treatment plan changes.
Main Results:
- The RISK INDEX demonstrated superior prognostic accuracy for 31-day mortality compared to clinical intuition and traditional scores (AUROC 0.84 vs. 0.65-0.76).
- RISK INDEX predictions diverged from clinician expectations in approximately half of cases, particularly among less experienced physicians.
- Despite high accuracy, the RISK INDEX did not significantly alter treatment plans (0.16% changes) or clinical outcomes, with perceived low added value by clinicians.
Conclusions:
- Prognostic accuracy alone is insufficient to ensure clinical impact in the emergency department setting.
- User-centered design, actionability, and trust are crucial for the successful integration of machine learning tools into clinical workflows.
- Future development should focus on creating clinically actionable insights rather than solely on predictive performance.
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