How do delirium and dementia increase length of stay of elderly general medical inpatients?

The purpose of this study was to identify the proximate causes through which dementia and delirium extend length of stay (LOS) in elderly general hospital patients. Among 93 patients age >/=65 years admitted to a tertiary-care teaching hospital through the emergency department, admission ratings of cognitive impairment, delirium, and dementia predicted the emergence of mental and behavioral manifestations of delirium and dementia in the hospital and greater LOS. Mental and behavioral manifestations also predicted greater LOS. On average, mental manifestations appeared first and were followed by behavioral manifestations, and the appearance of both types of manifestations occurred before the mean LOS. The results suggest that elderly patients with dementia and/or delirium who become symptomatic after admission to a general hospital first show mental signs and symptoms, then show behavioral disturbances, which appear to be the proximate causes of greater LOS.