Delirium in older persons

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Current Concepts

Delirium in Older Persons
Sharon K. Inouye, M.D., M.P.H. elirium, an acute decline in attention and cognition, is a common, life-threatening, and potentially preventable clinical syndrome among persons who are 65 years of age or older. The development of delirium often initiates a cascade ofevents culminating in the loss of independence, an increased risk of morbidity and mortality, and increased health care costs.1-6 Delirium in hospitalized older patients has assumed particular importance because the care of such patients accounts for more than 49 percent of all hospital days.7 Delirium complicates hospital stays for at least 20 percent of the 12.5 million patients 65 years of age orolder who are hospitalized each year and increases hospital costs by $2,500 per patient,8-10 so that about $6.9 billion (value in U.S. dollars in 2004) of Medicare hospital expenditures are attributable to delirium. Substantial additional costs accrue after hospital discharge because of the need for institutionalization, rehabilitation services, formal home health care, and informal caregiving.This report examines current clinical practice in delirium, identifies areas of controversy, and highlights areas for future research.

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From the Department of Medicine, Harvard Medical School, Boston. Address reprint requests to Dr. Inouye at the Aging Brain Center, Hebrew Senior Life, 1200 Centre St., Boston, MA 02131. N Engl J Med 2006;354:1157-65.
Copyright © 2006 Massachusetts MedicalSociety.

Epide miol o gy a nd Di agnos t ic Cr i ter i a
In direct contrast to dementia, which is a chronic confusional state, delirium is an acute confusional state. Rates of delirium are highest among hospitalized older patients, and the rates vary depending on the patients’ characteristics, setting of care, and sensitivity of the detection method. The prevalence of delirium at hospitaladmission ranges from 14 to 24 percent, and the incidence of delirium arising during hospitalization ranges from 6 to 56 percent among general hospital populations.11,12 Delirium occurs in 15 to 53 percent of older patients postoperatively11 and in 70 to 87 percent of those in intensive care.13 Delirium occurs in up to 60 percent of patients in nursing homes or post–acute care settings14,15 and in upto 83 percent of all patients at the end of life.16,17 Although the overall prevalence of delirium in the community is only 1 to 2 percent,18,19 the prevalence increases with age, rising to 14 percent among those more than 85 years old. Moreover, in 10 to 30 percent of older patients presenting to emergency departments, delirium is a symptom11 that often heralds the presence of life-threateningconditions. The mortality rates among hospitalized patients with delirium range from 22 to 76 percent,20 as high as the rates among patients with acute myocardial infarction or sepsis. The one-year mortality rate associated with cases of delirium is 35 to 40 percent.21 The diagnosis of delirium is primarily clinical and is based on careful bedside observation of key features. Although the criteriacontinue to evolve,22,23 the diagnostic algorithms that are most widely used are presented in the Supplementary Appendix (available with the full text of this article at www.nejm.org). Delirium is often unrecognized by the patients’ physicians and nurses,1,24 in part because of its fluctuating nature, its overlap with dementia, lack of formal cognitive assessment, underappreciation of its clinicalconsequences, and failure to consider the diagnosis important.
n engl j med 354;11 www.nejm.org march 16, 2006

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Cl inic a l Ch a r ac ter is t ic s
Because delirium remains a...