Geriatrics/original researchDelirium in the Emergency Department: An Independent Predictor of Death Within 6 Months
Introduction
Delirium occurs in 8% to 10% of older emergency department (ED) patients. 1, 2 This form of brain dysfunction is characterized by an acute change in cognition that cannot be better accounted for by a preexisting or evolving dementia. 3 Approximately 1.5 million older patients with delirium will be evaluated in the ED each year in the United States, 4 which is similar to the number of annual acute coronary syndromes, a disease with comparable mortality and morbidity. 5 Despite the magnitude of this problem, emergency physicians miss delirium in up to 75% of cases. 1, 2, 6
The lack of delirium recognition may be a result of a dearth of ED outcomes data. Predominantly from inhospital literature, delirium has been shown to be a marker for long-term death in noncritically ill and critically ill inpatients. 7, 8 Unfortunately, hospital-based studies have limited generalizability to the ED population because they exclude patients discharged from the ED and enrollment typically occurs in 24 to 48 hours after admission. 7 In addition, many of these studies include patients who developed delirium during their hospital course, 7, 8 and a significant proportion of inpatients who were classified as having delirium may not have been delirious in the ED.
Even less is known about delirium's effect on mortality in nursing home patients treated in the ED, despite being 7 times more likely to be delirious compared with community-dwelling elders. 9 Conclusions derived from general geriatric data sets have limited external validity to nursing home patients because they have higher rates of dementia, poorer functional status, and higher comorbidity burden. 9 There are approximately 1.5 million nursing home residents in the United States, and 43% of community-dwelling elders will enter a nursing home during their lifetime. 10 Because up to 25% of all nursing home patients will visit the ED for an acute illness, 11, 12 understanding how delirium affects nursing home patients is crucial.
Because there is a paucity of data about the relationship between delirium in the ED and long-term mortality, and little is known about its effect on nursing home patients, we sought to determine whether delirium is an independent predictor of 6-month mortality in older ED patients, regardless of their admission status, and to assess whether this relationship is modified by nursing home residence.
Section snippets
Study Design and Setting
This was a prospective cohort study conducted at a tertiary care, academic ED with an annual census of approximately 55,000 visits. Approximately 10% of patients were aged 65 years and older. Although no outcomes data from this cohort have been published, portions of this cohort have been used for previous publications that investigated delirium risk factors in ED patients, recognition of delirium by emergency physicians, and delirium in nursing home patients treated in the ED. 2, 9 The
Results
A total of 628 patients met enrollment criteria (Figure 1), and of these, 351 (55.9%) were admitted to the hospital, 58 (9.2%) were from the nursing home, 108 (17.2%) met criteria for delirium, and 81 (12.9%) died within 6 months. Patient demographics and characteristics stratified by delirium status are listed in Table 1. Patients who were delirious in the ED were more likely to be older and severely ill and have higher comorbidity burden. In addition, delirious patients were more likely to
Limitations
Our study has several notable limitations. First, there are several potential sources of selection bias. This was a convenience sample, and we did not enroll older patients who presented to the ED during early morning or late evening. Because patients who present during these times tend to be sicker, the proportion of deaths and patients with delirium may have been underestimated. There were also 163 (17.2%) patients who refused to participate in the study and 19 (2.0%) patients who did not
Discussion
There is a paucity of data about delirium in the ED and its relationship to long-term outcomes. To address this deficiency, we enrolled a large cohort of older ED patients and observed that patients with delirium were more likely to die at 6 months compared with those without delirium. This relationship persisted after adjusting for age, comorbidity burden, severity of illness, dementia, functional dependence, and nursing home residence. To our knowledge, our study is also the first to evaluate
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Please see page 245 for the Editor's Capsule Summary of this article.
Supervising editor: Knox H. Todd, MD, MPH
Author contributions: JHH, JS, RSD, ABS, and EWE conceived the study and designed the trial. JHH and EWE supervised the conduct of the trial and data collection. JHH managed the data, including its quality control. JHH, AS, and SE performed the data analysis. All authors interpreted the data and contributed the contents within the discussion section. JHH, AS, AM, and LS drafted the article, and all authors contributed substantially to its revision. JHH takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. The authors have stated that no such relationships exist. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This study was partially supported by the Emergency Medicine Foundation. Dr. Han received support from the Vanderbilt Physicians Scientist Development grant. Dr. Ely was supported in part by the National Institutes of HealthAG01023 and the Veterans Affairs Tennessee Valley Geriatric Research, Education, and Clinical Center.
Publication date: Available online April 3, 2010.
Reprints not available from the authors.