The relationship between a chief complaint of "altered mental status" and delirium in older emergency department patients.

BACKGROUND: Altered mental status is a common chief complaint among older emergency department (ED) patients. Patients with this chief complaint are likely delirious, but to the authors' knowledge, this relationship has not been well characterized. Additionally, health care providers frequently ascribe "altered mental status" to other causes, such as dementia, psychosis, or depression.
OBJECTIVES: The objective was to determine the relationship between altered mental status as a chief complaint and delirium.
METHODS: This was a secondary analysis of a cross-sectional study designed to validate three brief delirium assessments, conducted from July 2009 to March 2012. English-speaking patients who were 65 years or older and in the ED for <12 hours were included. Patients who were comatose or nonverbal or unable to follow simple commands prior to the acute illness were excluded. Chief complaints were obtained from the ED nurse triage assessment. The reference standard for delirium was a comprehensive psychiatrist assessment using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria. Sensitivity, specificity, positive likelihood ratio (LR), and negative LR with their 95% confidence intervals (CIs) were calculated using the psychiatrist's assessment as the reference standard.
RESULTS: A total of 406 patients were enrolled. The median age was 73.5 years old (interquartile range [IQR] = 69 to 80 years), 202 (49.8%) were female, 57 (14.0%) were nonwhite race, and 50 (12.3%) had delirium. Twenty-three (5.7%) of the cohort had chief complaints of altered mental status. The presence of this chief complaint was 38.0% sensitive (95% CI = 25.9% to 51.9%) and 98.9% specific (95% CI = 97.2% to 99.6%). The negative LR was 0.63 (95% CI = 0.50 to 0.78), and the positive LR was 33.82 (95% CI = 11.99 to 95.38).
CONCLUSIONS: The absence of a chief complaint of altered mental status should not reassure the clinician that delirium is absent. This syndrome will be missed unless it is actively looked for using a validated delirium assessment. However, patients with this chief complaint are highly likely to be delirious, and no additional delirium assessment is necessary.