Delirium in newly admitted elderly patients: a prospective study.

The prevalence, associated conditions and outcome of delirium were studied in a consecutive series of 184 patients admitted with acute illness to a department of health care of the elderly. Forty of these elderly subjects (22 per cent) met Diagnostic and Statistical Manual version 3 (revised) criteria for delirium. Screening for delirious patients using the abbreviated mental test on admission gave a high sensitivity (92 per cent). The conditions most commonly associated with delirium were infection and stroke. Onset of acute illness of less than 15 days, a reported history of dementia or recent confusion, and presence of a definite site of infection were much more likely in those with delirium. Serial use of the abbreviated mental test was a sensitive means of distinguishing delirious from other patients and may be useful in both the clinical and research setting. Delirious patients had more serious pre-existing disease than non-delirious patients. They had a higher number of admissions during the 2 years prior to the index admission, a higher mortality rate and a higher rate of transfer to long-stay care than other patients, but no difference in duration of admission. All acutely ill elderly people should undergo an abbreviated mental test on admission, and if abnormal, this should be repeated as it will aid detection of delirium.