Delirium and dementia: diagnostic criteria and fatality rates.

Medically ill patients diagnosed at index admission as delirious, i.e., suffering cognitive decline and an altered state of consciousness, had higher fatality rates than demented, cognitively intact or depressed patients. At a one-year follow-up the death rate of those who had been delirious was still higher than that of demented patients. Delirious patients were more likely to have a diffusely slow EEG, tachycardia and hyperthermia and lower mean systolic and diastolic blood pressure. These result validate the distinction between delirium and dementia and the importance of alteration of consciousness as a defining characteristics of delirium.