Days of Delirium Are Associated with 1-Year Mortality in an Older Intensive Care Unit Population

Abstract

Delirium is a frequent occurrence in older intensive care unit (ICU) patients, but the importance of the duration of delirium in contributing to adverse long-term outcomes is unclear. To examine the association of the number of days of ICU delirium with mortality in an older patient population. We performed a prospective cohort study in a 14-bed ICU in an urban acute care hospital. The patient population comprised 304 consecutive admissions 60 years of age and older. The main outcome was 1-year mortality after ICU admission. Patients were assessed daily for delirium with the Confusion Assessment Method for the ICU and a validated chart review method. The median duration of ICU delirium was 3 days (range, 1-46 d). During the follow-up period, 153 (50%) patients died. After adjusting for relevant covariates, including age, severity of illness, comorbid conditions, psychoactive medication use, and baseline cognitive and functional status, the number of days of ICU delirium was significantly associated with time to death within 1 year post-ICU admission (hazard ratio, 1.10; 95% confidence interval, 1.02-1.18). Number of days of ICU delirium was associated with higher 1-year mortality after adjustment for relevant covariates in an older ICU population. Investigations should be undertaken to reduce the number of days of ICU delirium and to study the impact of this reduction on important health outcomes, including mortality and functional and cognitive status.