Delirium is common in hospitalized elderly patients.
Postoperative delirium occurs in 10 to 15 percent of older general surgery patients and in 30 to 50 percent of older patients admitted with hip fractures or who are undergoing knee arthroplasty. The use of psychoactive drugs and the presence of azotemia, fracture, or abnormal serum sodium levels are independent risk factors for delirium in elderly hospitalized patients. In one study, significant risk factors for delirium in elderly medical patients during hospitalization included severe illness, cognitive impairment, visual impairment, and high ratio of blood urea nitrogen to creatinine, implying dehydration. In all studies, dementia or cognitive impairment is the single most important risk factor for delirium, perhaps reflecting impaired brain homeostasis in these highly vulnerable patients. These findings establish ways to both identify high-risk patients and prevent incident delirium through appropriate medical, behavioral, and pharmacological approaches.