Delirium in the intensive care unit: occurrence and clinical course in older patients

J Am Geriatr Soc. 2003 May;51(5):591-8. doi: 10.1034/j.1600-0579.2003.00201.x.


Objectives: To describe the occurrence of delirium in a cohort of older medical intensive care unit (ICU) patients and its short-term duration in the hospital and to determine the association between preexisting dementia and the occurrence of delirium.

Design: Prospective cohort study.

Setting: Fourteen-bed medical ICU of an 800-bed university teaching hospital.

Participants: One hundred eighteen consecutive patients aged 65 and older admitted to the ICU.

Measurements: Baseline characteristics were obtained through surrogate interviews and medical chart review. Dementia was determined using two validated surrogate-rated instruments. Delirium was assessed daily in the ICU using the Confusion Assessment Method (CAM) for the ICU (CAM-ICU). After discharge from the ICU, patients were followed for up to 7 days using the CAM.

Results: Delirium was present in 37 of 118 (31%) patients on admission. Only 45 patients had a normal mental status on admission, of whom 14 (31%) became delirious during their hospital stay. In the post-ICU period, delirium occurred in 40% of patients. Almost half of patients with delirium in the ICU had persistent delirium in the post-ICU period. Overall, 83 of 118 (70%) had delirium during hospitalization. Stupor or coma occurred in 44% of the patients overall, and 89% of survivors of stupor/coma progressed to delirium. Patients with dementia were 40% more likely to be delirious (relative risk = 1.4, 95% confidence interval = 1.1-1.7), even after controlling for comorbidity, baseline functional status, severity of illness, and invasive procedures.

Conclusion: Delirium is a frequent complication in older ICU patients and often persists beyond their ICU stay. Delirium in older ICU persons is a dynamic and complex process. Dementia is an important predisposing risk factor for the development of delirium in this population during and after the ICU stay.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Delirium / diagnosis
  • Delirium / epidemiology*
  • Delirium / etiology
  • Dementia / complications
  • Dementia / diagnosis
  • Dementia / epidemiology
  • Female
  • Humans
  • Intensive Care Units*
  • Male
  • Prospective Studies
  • Psychiatric Status Rating Scales
  • Respiration, Artificial