To evaluate the association between potential emergency department (ED)-based modifiable risk factors and subsequent development of delirium among hospitalized older adults free of delirium at the time of ED stay.

Observational cohort study of patients aged ≥75 years who screened negative for delirium in the ED, were subsequently admitted to the hospital, and had delirium screening performed within 48 h of admission. Potential ED-based risk factors for delirium included ED length of stay (LOS), administration of opioids, benzodiazepines, antipsychotics, or anticholinergics, and the placement of urinary catheter while in the ED. Odds ratios (OR) and mean differences (MD) with 95% confidence intervals (CIs) were calculated.

Among 472 patients without delirium in the ED (mean age 84 years, 54.2% females), 33 (7.0%) patients developed delirium within 48 h of hospitalization. The ED LOS of those who developed delirium was similar to those who did not develop delirium (312.1 vs 325.6 min, MD -13.5 min, CI -56.1 to 29.0). Patients who received opioids in the ED were as likely to develop delirium as those who did not receive opioids (7.2% vs 6.9%: OR 1.04, CI 0.44 to 2.48). Patients who received benzodiazepines had a higher risk of incident delirium, the difference was clinically but not statistically significant (37.3% vs 6.5%, OR 5.35, CI 0.87 to 23.81). Intermittent urinary catheterization (OR 2.05, CI 1.00 to 4.22) and Foley placement (OR 3.69, CI 1.55 to 8.80) were associated with a higher risk of subsequent delirium. After adjusting for presence of dementia, only Foley placement in the ED remained significantly associated with development of in-hospital delirium (adjusted OR 3.16, CI 1.22 to 7.53).

ED LOS and ED opioid use were not associated with higher risk of incident delirium in this cohort. Urinary catheterization in the ED was associated with an increased risk of subsequent delirium. These findings can be used to design ED-based initiatives and increase delirium prevention efforts.