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

ObjectivesTo determine whether emergency department (ED) length of stay before ward admission is associated with incident delirium in older adults. DesignProspective cohort study. SettingHospital. ParticipantsIndividuals aged 75 and older without delirium at ED entry, coma, aphasia, stroke, language barrier, psychiatric disorder, or alcohol abuse (N=330). MeasurementsOn 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 3days after ward admission, the presence of delirium (defined as 1 delirium episodes within 72hours) 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. ResultsED length of stay longer than 10hours (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. ConclusionED length of stay longer than 10hours was associated with greater risk of delirium in hospitalized older adults, after adjusting for age and cognitive impairment.