Length of Stay in the Emergency Department and Occurrence of Delirium in Older Medical Patients

Objectives: To determine whether emergency department (ED) length of stay before ward admission is associated with incident delirium in older adults. Design: Prospective cohort study. Setting: Hospital. Participants: Individuals aged 75 and older without delirium at ED entry, coma, aphasia, stroke, language barrier, psychiatric disorder, or alcohol abuse (N = 330). Measurements: On ED admission, individuals underwent standardized evaluation of comorbidity (Cumulative Illness Rating Scale), cognitive impairment (Short Portable Mental Status Questionnaire), functional independence (activities of daily living, instrumental activities of daily living), pain (Numeric Rating Scale), and acute clinical conditions (Acute Physiology and Chronic Health Evaluation II). During the first 3 days after ward admission, the presence of delirium (defined as ≥1 delirium episodes within 72 hours) was assessed daily using a rapid assessment for delirium (4AT scale). ED length of stay was calculated as the time (hours) between ED registration and when the person left the ED. Results: ED length of stay longer than 10 hours (odds ratio (OR) = 2.23, 95% confidence interval (CI) = 1.13–4.41), moderate to severe cognitive impairment (OR = 5.47, 95% CI = 2.76–10.85), and older age (OR = 1.07, 95% CI = 1.01–1.13) were associated with delirium onset. Conclusion: ED length of stay longer than 10 hours was associated with greater risk of delirium in hospitalized older adults, after adjusting for age and cognitive impairment.