Long-Term Outcomes in ICU Patients with Delirium: A Population-based Cohort Study

Rationale: Delirium is common in the ICU and portends worse ICU and hospital outcomes. The effect of delirium in the ICU on post-hospital discharge mortality and health resource use is less well known. Objectives: To estimate mortality and health resource use 2.5 years after hospital discharge in critically ill patients admitted to the ICU. Methods: This was a population-based, propensity score-matched, retrospective cohort study of adult patients admitted to 1 of 14 medical-surgical ICUs from January 1, 2014, to June 30, 2016. Delirium was measured by using the 8-point Intensive Care Delirium Screening Checklist. The primary outcome was mortality. The secondary outcome was a composite measure of subsequent emergency department visits, hospital readmission, or mortality. Measurements and Main Results: There were 5,936 propensity score-matched patients with and without a history of incident delirium who survived to hospital discharge. Delirium was associated with increased mortality 0-30 days after hospital discharge (hazard ratio, 1.44 [95% confidence interval, 1.08-1.92]). There was no significant difference in mortality more than 30 days after hospital discharge (delirium: 3.9%, no delirium: 2.6%). There was a persistent increased risk of emergency department visits, hospital readmissions, or mortality after hospital discharge (hazard ratio, 1.12 [95% confidence interval, 1.07-1.17]) throughout the study period. Conclusions: ICU delirium is associated with increased mortality 0-30 days after hospital discharge.