Delirium is one of the most frequent, dangerous, and costly complications associated with hospitalization in the older adult population. Prior studies on delirium, however, lacked data on the course of delirium in older adults admitted to Surgical Intensive Care Units (SICUs). Therefore, the objectives of this prospective, cohort study were to: (1) determine the frequency with which older adults admitted to SICUs have evidence of pre-existing delirium; (2) determine the frequency with which older adults develop delirium during their SICU stay and (3) examine the course, duration and characteristics of delirium throughout hospitalization. A secondary objective of this study was to compare delirious and nondelirious subjects with respect to hospital and SICU length of stay (LOS), mortality rates, post discharge institutionalization rates, and discharge functional and cognitive ability. The convenience sample included 114 subjects aged 65 and older admitted to the SICUs of a 672 bed university teaching hospital. Baseline characteristics were obtained through surrogate interviews and medical chart reviews. Subjects were screened for evidence of dementia and impairment in activities of daily living by using validated surrogate-rated instruments. Subjects were screened for delirium daily throughout their hospitalization. The subjects\u27 functional and cognitive ability and post-discharge institutionalization placement was assessed within 24 hours of hospital discharge. A considerable number (18.42%) of older adults were found to have evidence of dementia on admission to the SICU. This diagnosis was frequently unrecognized by both healthcare providers and the elders\u27 surrogates. While few elders were admitted to the SICU with evidence of pre-existing delirium (2.63%), a substantial number of older adults newly developed delirium during either their SICU (28.29%) or Post SICU (22.67%)stay. Episodes of deep sedation/unarousal occurred in 9.65% of the sample overall. Finally, older adults who experienced delirium in the SICU had significantly longer hospital and SICU LOS, more frequent discharge to institutional care, and decreased functional ability at hospital discharge than nondelirious elders. This study will serve as the first step in a program of research aimed at decreasing the morbidity associated with critical illness in the older adult population
