OBJECTIVE:To determine the independent contribution of admission delirium to hospital outcomes including mortality, institutionalization, and functional decline.
DESIGN:Three prospective cohort studies.
SETTING: Three university-affiliated teaching hospitals.PATIENTS: Consecutive samples of 727 patients, aged 65 years and older.
MEASUREMENTS AND MAIN RESULTS:
Delirium, defined as an acute disorder of attention and global cognitive functioning, has assumed increasing importance in the United States, with the burgeoning population of older citizens. In 1993, 35% of the population aged 65 years and older was hospitalized during the year, accounting for 36% of all hospital stays and 48% of all days of hospital care. 1 The oldest group ( Ͼ 75 years) is the most rapidly growing sector of the U.S. population, 1 and is particularly vulnerable to developing delirium during acute illness and hospitalization. 2 Previous studies have estimated that delirium occurs in 14% to 56% of elderly hospitalized patients, with associated hospital mortality rates of 10% to 65%. 2 Previous studies have documented that delirium is associated with poor outcomes, such as increased mortality rates, prolonged length of hospital stay, increased rates of institutional placement, and functional and cognitive decline. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, the unanswered question remains: Does delirium itself contribute to this poor prognosis, or does delirium simply serve as a marker identifying patients with poor prognostic features due to severe illness, dementia, functional impairment, advanced age, and the like? Unfortunately, many of the previous studies, which were not all designed to address this research question directly, were hindered by inadequate control for these potential confounders and by small numbers of relatively infrequent outcome events.The objective of the present study was to examine the independent contribution of baseline delirium to hospital mortality, institutionalization, functional decline, and length of stay in three large prospective cohort studies of elderly hospitalized patients. 20 Uniform prospective data collection for this project facilitated collection of standardized information on delirium, study outcomes, and potential confounders. Our underlying hypothesis was that baseline delirium (present at admission) would be an important prognostic predictor even after controlling for underlying illness severity, age, dementia and functional status.
