Delirium in the Emergency Department: An Independent Predictor of Death Within 6 Months

Abstract

Objectives Delirium’s adverse effect on long-term mortality in older hospitalized patients is well documented, while its effect in older emergency department (ED) patients remains unclear. Similarly, the consequences of delirium on nursing home patients seen in the ED are also unknown. As a result, we sought to determine if delirium in the ED was independently associated with 6-month mortality in older patients and if this relationship was modified by nursing home status. Methods Our prospective cohort study was conducted at a tertiary care, academic ED using convenience sampling, and included English speaking patients who were 65 years and older and were in the ED for less than 12 hours at the time of enrollment. Patients were excluded if they refused consent, were previously enrolled, were unable to follow simple commands at baseline, were comatose, or had incomplete data. The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) was used to determine delirium and was administered by trained research assistants. Cox proportional hazard regression was performed to determine if delirium in the ED was independently associated with 6-month mortality after adjusting for age, comorbidity burden, severity of illness, dementia, functional dependence, and nursing home residence. To test whether the effect of delirium in the ED on 6-month mortality was modified by nursing home residence, an interaction term (delirium*nursing home) was incorporated into the multivariable model. Hazard ratios (HR) with their 95% confidence intervals (95% CI) were reported. Results Of the 628 patients enrolled, 108 (17.2%) were delirious in the ED and 58 (9.2%) were from the nursing home. For the entire cohort, the 6-month mortality rate was higher in the delirious group compared to the non-delirious group (37.0% versus 14.3%). Delirium was an independent predictor of increased 6-month mortality (HR = 1.72, 95% CI: 1.04 – 2.86) after adjusting for age, comorbidity burden, severity of illness, dementia, functional dependence, and nursing home residence. The “delirium*nursing home” interaction was non-significant (p=0.86), indicating that place of residence had no effect on the relationship between delirium in the ED and 6-month mortality. Conclusion Delirium in older ED patients is an independent predictor of increased 6-month mortality and this relationship appears to be present regardless of nursing home status.