ICU Delirium Common in Older Patients

Abstract & Commentary

Synopsis: Among patients aged 65 or older, 31% were delirious on admission to the ICU, and 70% experienced delirium at some time during their hospitalization.

Source: McNicoll L, et al. Delirium in the intensive care unit. J Am Geriatr Soc. 2003;51:591-598.

In this study from Yale-New Haven hospital, 118 consecutive patients aged 65 and older who were admitted to the medical ICU were evaluated using 2 different instruments for assessing delirium. Delirium was present in 31% (37/118) of the patients at the time of admission to the ICU. Only 38% (45/118) of the patients had normal mental status on admission to the ICU, and 31% of these (14/45) became delirious during their hospital stay. Delirium also occurred in 40% of patients in the post-ICU phase of hospitalization, including its persistence or recurrence in half of those who were delirious in the ICU. All told, 70% (83/118) of the patient cohort experienced delirium during the hospital stay. Patients with dementia were 40% more likely to develop delirium in the hospital than patients who were not demented on admission (relative risk, 1.4; 95% confidence interval, 1.1-1.7).

Comment by David J. Pierson, MD

Delirium can be defined as an acute confusional state that usually occurs in the face of medical illness or the effects of drugs. It is distinguished from dementia by its acute onset, the fact that delirious patients experience an acute change in level of consciousness, and the presence of a high level of inattention. This study from the MICU of a large university teaching hospital shows that delirium is very common in older patients who require an ICU stay. If patients have evidence of dementia prior to ICU admission, they are especially likely to become delirious, according to the results of this study.

Delirium can be as distressful to patients as pain. It is all too easy for ICU clinicians to focus on physiology and "the numbers" in patients admitted to the ICU. This study points out that the patient’s experience of acute illness and its predilection for inducing acute delirium should be as much on the clinician’s radar screen as the physiological manifestations and their manipulation.

Dr. Pierson is Professor of Medicine University of Washington Medical Director Respiratory Care Harborview Medical Center, Seattle.