Long-Term Cognitive Impairment after Critical Illness

BackgroundSurvivors of critical illness often have a prolonged and disabling form of cognitive impairment that remains inadequately characterized. MethodsWe enrolled adults with respiratory failure or shock in the medical or surgical intensive care unit (ICU), evaluated them for in-hospital delirium, and assessed global cognition and executive function 3 and 12 months after discharge with the use of the Repeatable Battery for the Assessment of Neuropsychological Status (population age-adjusted mean [SD] score, 10015, with lower values indicating worse global cognition) and the Trail Making Test, Part B (population age-, sex-, and education-adjusted mean score, 5010, with lower scores indicating worse executive function). Associations of the duration of delirium and the use of sedative or analgesic agents with the outcomes were assessed with the use of linear regression, with adjustment for potential confounders. ResultsOf the 821 patients enrolled, 6% had cognitive impairment at baseline, and delirium developed in 74% during the hospital stay. At 3 months, 40% of the patients had global cognition scores that were 1.5 SD below the population means (similar to scores for patients with moderate traumatic brain injury), and 26% had scores 2 SD below the population means (similar to scores for patients with mild Alzheimer's disease). Deficits occurred in both older and younger patients and persisted, with 34% and 24% of all patients with assessments at 12 months that were similar to scores for patients with moderate traumatic brain injury and scores for patients with mild Alzheimer's disease, respectively. A longer duration of delirium was independently associated with worse global cognition at 3 and 12 months (P=0.001 and P=0.04, respectively) and worse executive function at 3 and 12 months (P=0.004 and P=0.007, respectively). Use of sedative or analgesic medications was not consistently associated with cognitive impairment at 3 and 12 months. ConclusionsPatients in medical and surgical ICUs are at high risk for long-term cognitive impairment. A longer duration of delirium in the hospital was associated with worse global cognition and executive function scores at 3 and 12 months. (Funded by the National Institutes of Health and others; BRAIN-ICU ClinicalTrials.gov number, NCT00392795.) In this study, patients treated in ICUs were at high risk for new cognitive impairment during 12 months of follow-up, with 24% of patients having deficits similar in severity to those in Alzheimer's disease. A longer duration of delirium was associated with worse cognitive scores. Survivors of critical illness frequently have a prolonged and poorly understood form of cognitive dysfunction,(1)-(4) which is characterized by new deficits (or exacerbations of preexisting mild deficits) in global cognition or executive function. This long-term cognitive impairment after critical illness may be a growing public health problem, given the large number of acutely ill patients being treated in intensive care units (ICUs) globally.(5) Among older adults, cognitive decline is associated with institutionalization,(6) hospitalization,(7) and considerable annual societal costs.(8),(9) Yet little is known about the epidemiology of long-term cognitive impairment after critical illness. Delirium, a form of acute brain ...