Survivors of critical illness often have a prolonged and disabling form of cognitive
impairment that remains inadequately characterized.
We 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, 100±15, with lower values indicating worse global cognition) and the
Trail Making Test, Part B (population age-, sex-, and education-adjusted mean score,
50±10, 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.
Of 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.
Patients 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.).