A new metric to describe the symptoms of delirium may help researchers and clinicians better study aging-related ailments such as Alzheimer’s and other dementias.

Based on the “Confusion Assessment Method,” the new CAM-S standardizes measurements of delirium, defined as the sudden onset of confusion often brought by dementia-related illnesses, surgery, or hospitalization. Although delirium might seem inevitable as one ages, the common condition complicates many hospital stays for elderly Americans — and is associated with as many as a third of deaths during hospitalization.

Every year, dementia costs the U.S. health care system more than $182 billion per year, says Sharon K. Inouye, who directs the Aging Brain Center at Harvard University’s medical school.

"Currently, the CAM is the most widely used tool in the world to screen for delirium,” Inouye said in a university news release. "Our study is the first to develop and test this important new methodology, and to demonstrate the validity and reliability of the CAM-S, a novel approach to measure delirium severity."

In developing the metric, Inouye’s team tested the CAM-S on two groups of study volunteers, including 300 patients ages 70 and older who were scheduled for major surgery as part of a study on surgery recovery among the elderly. The researchers developed the metric to include a short- and long-form version, the results of which both predicted hospital stay and eventual outcomes for the patients.

Working backward, the researchers found that CAM-S scores matched the clinical outcomes for patients with a high degree of accuracy, predicting nursing home placement, functional and cognitive decline, death, and even medical costs associated to hospitalization and longer-term care. The higher the CAM-S score, the worse the outcome. Among findings, hospital stays for patients experiencing delirium are nearly double the average of seven days — at 13 days for those with the most severe cases of delirium.

Those patients with severe delirium, measured in degrees on the CAM-S short-form version, also cost the health system nearly double at $13,200, compared to about $5,000 for patients with delirium. Similar results were seen when using the long-form version of the diagnostic, which includes 10 questions as opposed to just four.

"Our findings demonstrate that the CAM-S provides a new standardized severity measure with high inter-rater reliability, and a strong association with clinical outcomes related to delirium,” Inouye said. “We believe that this measure holds great promise to improve understanding of the effects of delirium on clinical care, prognosis, pathophysiology, and response to treatment.”

The researchers say they hope the new metric will ultimately help to improve the quality of life for older Americans suffering from the chronic condition.

 

Source: Inouye SK, et al. Annals of Internal Medicine. 2014.