Association between delirium in the intensive care unit and subsequent neuropsychiatric disorders

BACKGROUND: Patients in the intensive care unit (ICU) are known to be at increased risk of developing delirium, but the risk of subsequent neuropsychiatric disorders is unclear. We therefore sought to examine the association between the presence of delirium in the ICU and incident neuropsychiatric disorders (including depressive, anxiety, trauma-and-stressor-related, and neurocognitive disorders) post-ICU stay among adult medical-surgical ICU patients. METHODS: Retrospective cohort study utilizing clinical and administrative data from both inpatient and outpatient healthcare visits to identify the ICU cohort and diagnostic information 5 years prior to and 1 year post-ICU stay. Patients ≥ 18 years of age admitted to one of 14 medical-surgical ICUs across Alberta, Canada, January 1, 2014–June 30, 2016, and survived to hospital discharge were included. The main outcome of interest was a new diagnosis of any neuropsychiatric disorder 1 year post-ICU stay. The exposure variable was delirium during the ICU stay identified through any positive delirium screen by the Intensive Care Unit Delirium Screening Checklist (ICDSC) during the ICU stay. RESULTS: Of 16,005 unique patients with at least one ICU admission, 4033 patients were included in the study of which 1792 (44%) experienced delirium during their ICU stay. The overall cumulative incidence of any neuropsychiatric disorder during the subsequent year was 19.7% for ICU patients. After adjusting for hospital characteristics using log-binomial regression, patients with delirium during the ICU stay had a risk ratio (RR) of 1.14 (95% confidence interval [CI] 0.98–1.33) of developing any neuropsychiatric disorder within 1 year post-ICU compared to those who did not experience delirium. Delirium was significantly associated with neurocognitive disorders (RR 1.59, 95% CI 1.08–2.35), but not depressive disorders (RR 1.16, 95% CI 0.92–1.45), anxiety (RR 1.16, 95% CI 0.92–1.47), and trauma-and-stressor-related (RR 0.82, 95% CI 0.53–1.28) disorders. CONCLUSIONS: The diagnosis of new onset of neurocognitive disorders is associated with ICU-acquired delirium. In this study, significant associations were not observed for depressive, anxiety, and trauma-and-stressor-related disorders.