Arch Intern Med
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We evaluated the occurrence and persistence of delirium in 325 elderly patients admitted to a teaching hospital from either a defined community or a long-term care facility. Of the study participants, 34 (10.5%) had Diagnostic and Statistical Manual of Mental Disorders, Third Edition--defined delirium at initial evaluation; of the remaining patients, 91 (31.3%) developed new-onset delirium. An additional 110 patients also experienced individual symptoms of delirium without meeting full criteria. ⋯ Delirium was not associated with an increased risk of mortality, but it was associated with a prolonged hospital stay and an increased risk of institutional placement among community-dwelling elderly. Only five patients (4%) experienced resolution of all new symptoms of delirium before hospital discharge, and only 20.8% and 17.7%, respectively, had resolution of all new symptoms by 3 and 6 months after hospital discharge. These data suggest that delirium is a common disorder that may be substantially less transient than currently believed and that incomplete manifestations of the syndrome may be frequent.