Background We sought to determine the prevalence of delirium in a Thai emergency department (ED). The secondary objective was to identify risk factors and short-term outcomes in delirious elderly ED patients.

Methods This was a prospective cross-sectional study in the ED of an urban tertiary care hospital. Patients aged ≥65 years who presented to the ED were included. We excluded patients who had severe dementia, were not responsive to verbal stimuli, had severe trauma and were blind, deaf, aphasic or unable to speak Thai. Delirium was determined using the Confusion Assessment Method for the Intensive Care Unit. We collected 30-day mortality rate, hospital length of stay and revisit rate as short-term outcomes.

Results We had a final sample size of 232 patients; 27 (12%) were delirious in the ED, of which 16 (59%) were not recognised to be delirious by the emergency physician. Multivariable logistic regression analysis showed dementia (adjusted OR (AOR) 13.1; 95% CI 2.9 to 59.6), auditory impairment (AOR 4.8; 95% CI 1.6 to 13.8) and ED diagnosis of metabolic derangement (AOR 6.5; 95% CI 1.6 to 26.8) were associated with delirium in the ED. Delirium was associated with a higher mortality rate than those without delirium (15% vs 2%, p=0.004).

Conclusions In one middle-income country, elderly ED patients were delirious >10% of the time. Delirium was underdiagnosed and was associated with an increased 30-day mortality rate. Delirium screening needs to be improved, potentially focusing on high-risk patients.