Epidemiology of delirium.

Delirium is one of the most frequent symptoms of disease in the elderly. A large variation of incidence and prevalence data is reported probably due to different patient populations and inconsistent diagnostic criteria. In medical and surgical elderly inpatients recent studies report a prevalence rate of approximately 15% and in postoperative patients the incidence and prevalence rates vary greatly, 7-52%, depending on patient population and clinical setting. In nursing homes the prevalence is even higher and delirium is often combined with dementia. Data supports the statement that delirium is most often found in hospitalized somatically ill elderly patients. As a consequence of the rising number of elderly in hospitals we have to expect an increase in the prevalence and incidence of delirium.