Development and internal validation of a clinical risk score for early delirium detection in older emergency department patients

Delirium is a common but frequently underrecognized neuropsychiatric syndrome among older adults in the emergency department (ED), associated with prolonged hospitalization and increased mortality. To develop a clinical risk score for early delirium detection in older emergency department patients. We conducted a prospective cohort study in the ED of a tertiary hospital from July 2024 to July 2025. Patients aged ≥ 65 years who remained in the ED for > 4 h were assessed using the Thai version of the Confusion Assessment Method intensive care unit (CAM-ICU) within 12 h of arrival. Demographic data, comorbidities, functional status, medications, presenting features, vital signs, laboratory values, and ED diagnoses were collected. Multivariable logistic regression was used to derive a clinical risk score, which was evaluated area under the receiver operating characteristic curve (AuROC). Among 380 enrolled patients, 102 (26.8%) were identified with delirium. Five independent variables were included in the final model: age 70–79 years (1 point); age 80–89 years, CKD stage III–V, or prior cerebrovascular accident (12 points); age ≥ 90 years (29 points); cirrhosis (24 points); and dementia (41 points), yielding a total score range of 0–118. The score demonstrated good discriminative performance (AuROC 0.79; 95% CI 0.74–0.84). Delirium occurred in 17.97% of patients with low-risk scores (0–24) and 57.65% of those with high-risk scores (≥ 25). This simple, clinically applicable risk score, based on five readily available variables, shows good ability to identify older ED patients at risk for delirium. Early risk stratification using this tool may support timely preventive and monitoring strategies in the ED. Trial registration: The trial was retrospectively registered in the Thai Clinical Trial Registry, identification number TCTR2021082700 on 25 November 2025.