Study: delirium presentation predicts mortality

July 6, 2009

The way certain patients present in the post-acute hospital setting with delirium, a common, preventable but life-threatening acute confusional state, predicts mortality, according to a study conducted by the Institute for Aging Research of Hebrew SeniorLife.

Patients with severe, hypoactive delirium, characterized by slowing or lack of movement and unresponsiveness, have the worst six-month survival rate of any class of the disease. Those with mild, hypoactive delirium have a significantly higher likelihood of dying than patients with other, milder symptoms.

"The association of the delirium classes on mortality depends on the presence or absence of dementia," says lead author Frances Yang, Ph.D., an assistant scientist at the Institute for Aging Research and an instructor in psychiatry at Brigham and Women's Hospital and Harvard Medical School. "Among patients who did not have dementia, it was delirium severity rather than motoric subtype that was associated with higher risk of mortality at six months."

The study, published in the May/June issue of the journal Psychosomatics, is the first to link characteristics of delirium, called subtypes, with disease severity. The four subtypes of delirium are normal, hypoactive, hyperactive (symptoms range from mild restlessness to constant movement and agitation) and mixed, which combines both hypo- and hyperactive elements.

Using two standard assessment tools, researchers at the Institute's Aging Brain Center examined whether the classic psychomotor subtypes of delirium are reflected by delirium severity. In addition, they sought to determine if the subtypes were able to predict mortality.

Dr. Yang's co-author, Edward Marcantonio, M.D., an associate professor of medicine at Beth Israel Deaconess Medical Center and Harvard Medical School, and colleagues screened more than 4,000 patients at eight Boston-area skilled nursing facilities using the Confusion Assessment Method and the Memorial Delirium Assessment Scale, two standard tools to detect delirium. More than 400 of these patients were found to have delirium and were followed over six months.

Delirium is an acute and relatively sudden—over hours or days—decline in attention, perception and cognition. It is generally caused by severe physical illness, often in the elderly, or any process that interferes with the normal metabolism and function of the brain. An estimated 14 percent to 24 percent of patients admitted to the hospital suffer from episodes of delirium. A recent study by Aging Brain Center investigators found that delirium rapidly accelerates memory decline in Alzheimer's disease patients.

"Our data reinforce the need to systematically assess patients for delirium at post-acute care admission, while considering dementia status," says Dr. Yang. "The findings demonstrate the importance of examining psychomotor subtype and the severity of delirium in predicting mortality."

Source: Hebrew SeniorLife Institute for Aging Research