# Validation of 4 Risk Stratification Tools for Delirium in the Emergency Department

## TL;DR

This study tested four tools to predict delirium in older emergency department patients and found two to be highly accurate for early detection.

## Contribution

The study validates the applicability of four delirium risk stratification tools in the emergency department setting.

## Key findings

- The REDEEM score showed the highest predictive accuracy for delirium detection in the ED.
- The MDP tool, originally designed for hospitalized patients, also demonstrated strong performance in the ED.
- Three of the four tools performed comparably to their original studies, suggesting potential for clinical integration.

## Abstract

Are previously developed delirium risk stratification tools applicable to a different setting in the emergency department (ED)?

In this prognostic study including 44 578 patients, 3 of the 4 delirium scores demonstrated performance that was comparable with the scores attained in the original studies. The Recognizing Delirium in Emergency Medicine (REDEEM) score demonstrated the strongest predictive capacity, and the Mayo Delirium Prediction (MDP) tool, despite being developed for hospitalized patients, exhibited a high degree of accuracy in detecting delirium in ED patients.

These findings suggest that the REDEEM score and the MDP tool may be valid instruments to potentially improve delirium detection rates in the ED.

This cohort study validates 4 different risk stratification tools for detecting delirium among patients in the emergency department.

Validation of prognostic tools is an essential component of their integration into clinical practice.

To validate 4 delirium risk stratification tools in an independent emergency department (ED) cohort.

This prognostic study included a retrospective cohort of patients 65 years or older who presented to an academic ED between January 1, 2021, and December 31, 2024. Data were analyzed from February 10 to August 21, 2025.

Delirium screening included the Delirium Triage Screen followed by the brief Confusional Assessment Method as part of the standard of care. Four delirium risk scores were obtained, including the Kennedy rule, the Zucchelli rule, the Mayo Delirium Prediction (MDP) tools, and the Recognizing Delirium in Emergency Medicine (REDEEM) score.

Main outcomes included risk score performances and diagnostic test accuracy measured using the area under the receiver operating characteristics curve (AUROC), sensitivity, specificity, negative (NPV) and positive (PPV) predictive values, and positive and negative likelihood ratios (LRs) with 95% CIs. Secondary outcomes were discriminative and calibration measures.

A total of 44 578 patients were included, of whom 1701 (3.8%) were diagnosed with delirium. The median age was 80.0 (IQR, 75.0-85.0) years, and 22 786 patients (51.1%) were female. The Kennedy rule had an AUROC of 0.777 (95% CI, 0.766-0.789). At a cutoff of 5, sensitivity was 0.55 (95% CI, 0.52-0.57); specificity, 0.85 (95% CI, 0.84-0.85); positive LR, 3.54 (95% CI, 3.37-3.72); negative LR, 0.54 (95% CI, 0.51-0.57); PPV, 0.12 (95% CI, 0.12-0.13); and NPV, 0.98 (95% CI, 0.98-0.98). The Zucchelli tool had an AUROC of 0.701 (95% CI, 0.686-0.713). At a cutoff of 5, sensitivity was 0.68 (95% CI, 0.66-0.70); specificity, 0.66 (95% CI, 0.65-0.66); positive LR, 1.99 (95% CI, 1.92-2.06); negative LR, 0.49 (95% CI, 0.45-0.52); PPV, 0.07 (95% CI, 0.07-0.08); and NPV, 0.98 (95% CI, 0.98-0.98). The MDP tool had an AUROC of 0.898 (95% CI, 0.891-0.905). At a 30% cutoff, sensitivity was 0.51 (95% CI, 0.48-0.53); specificity, 0.95 (95% CI, 0.95-0.95); positive LR, 9.69 (95% CI, 9.11-10.31); negative LR, 0.52 (95% CI, 0.50-0.55); PPV, 0.28 (95% CI, 0.26-0.29); and NPV, 0.98 (95% CI, 0.98-0.98). The REDEEM score demonstrated the highest AUROC at 0.921 (95% CI, 0.914-0.929). Using a cutoff of 11 or greater, sensitivity was 0.83 (95% CI, 0.81-0.85); specificity, 0.92 (95% CI, 0.91-0.92), negative LR, 0.18 (95% CI, 0.17-0.20); positive LR, 9.91 (95% CI, 9.54-10.29); PPV, 0.28 (95% CI, 0.27-0.29); and NPV, 0.99 (95% CI, 0.99-0.99).

In this prognostic study comparing 4 delirium tools to improve delirium detection and identify high-risk patients, the REDEEM score and the MDP tool had better performance for delirium detection in the ED. These findings lay the groundwork for integrating validated risk stratification into ED workflows to improve early delirium detection and inform prevention strategies for high-risk older adults.