Algorithm for Bedside Diagnosis of Delirium

Abstract

Bruce Jancin is with the Denver bureau of Elsevier Global Medical News. DALLAS – The Confusion Assessment Method diagnostic algorithm for delirium is a highly useful bedside diagnostic tool when a formal psychiatric evaluation is difficult to come by, Dr. Robert M. Palmer said at the annual meeting of the Society of Hospital Medicine. The Confusion Assessment Method (CAM) is simple and quick, with a sensitivity and specificity in excess of 90%, added Dr. Palmer, head of the section of geriatric medicine at the Cleveland Clinic Foundation. Some in long-term care prefer the Delirium-O-Meter, which is used primarily by nursing staff (see story above). The algorithm, developed by Dr. Sharon K. Inouye of Harvard Medical School, Boston, focuses on several classic features of delirium: acute onset and fluctuating course, inattention, disorganized thinking, and altered consciousness. For a diagnosis of delirium to be made, both features 1 and 2 plus either feature 3 or 4 must be present. Feature 1–acute onset and fluctuating course–involves information readily obtained from a family member or other caregiver. Feature 2–inattention–requires some form of objective documentation. The Mini-Mental State Examination is a good test, but some busy physicians think it takes too long. Dr. Palmer said he prefers the digit span test. Speaking slowly in a mono-tone at 1-second intervals, he asks the patient to repeat numbers after him. A person who can repeat a 5-digit number is very unlikely to have delirium. “Most delirious patients forget what you ask them to do or get distracted by a noise or a passing person in the hallway.” Delirium often overlaps with dementia. After all, Alzheimer's disease, the most common type of dementia, is present in about 20% of 80-year-olds and 30% of 85-year-olds. Factors helpful in making the distinction include onset, which is abrupt in delirium and gradual in dementia, and attention span, which is diminished in delirium but unaffected in dementia. Individuals with delirium are typically hyperactive or hypoactive, while psychomotor changes occur only late in dementia. Consciousness is clouded and fluctuating in delirium but unaffected in dementia.