Delirium is an acute confusional state characterized by altered or fluctuating mental status, inattention, and either disorganized thinking or an altered level of consciousness. This form of organ dysfunction occurs in up to 10% of older emergency department (ED) patients and is associated with worsening mortality, prolonged hospital length of stay, higher health care costs, and accelerated functional and cognitive decline. Despite the negative consequences of delirium, the majority of cases are unrecognized by emergency physicians because it is not routinely screened for. In an effort to facilitate delirium screening, the investigators sought to validate three brief delirium assessments in the ED setting.

Delirium is often missed because emergency physicians do not routinely screen for this diagnosis. Most delirium assessments can take up to 10 minutes to perform making them less likely to be incorporated into the routine physician assessment. Using brief (<2 minutes) and easy to use delirium assessments may ameliorate this quality of care issue. The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) possesses these characteristics, but has only been validated in mechanically and non-mechanically ventilated intensive care unit patients. Recently, the investigators also developed the Brief Confusion Assessment Method (B-CAM) which is a modification of the CAM-ICU. The benefit is that it takes even less time than the CAM-ICU. The investigators also developed the Emergency Department Delirium Triage Screen (ED-DTS) designed to be highly sensitive and moderately specific delirium assessment for the nurse's triage assessment. It is hypothesized that a negative ED-DTS would rule out delirium, while a positive ED-DTS would require a more formal delirium assessment such as the CAM-ICU and B-CAM. These new delirium assessments require validation in older ED patients. As result, the investigators propose the following and the following specific aims:

Aim #1: To validate the B-CAM in older ED patients. The B-CAM will be performed by a clinical trials associate (CTA) and principal investigator in 200 ED patients that are > 65 years old. This instrument will be validated against a psychiatrist's Diagnostic and Statistical Manual of Mental Disorders, 4th. Edition Text Revision assessment as the reference standard.

Aim #2: To validate the CAM-ICU in older ED patients. The CAM-ICU will be performed by a clinical trials associate (CTA) and principal investigator in approximately 200 ED patients that are > 65 years old. This instrument will be validated against a psychiatrist's Diagnostic and Statistical Manual of Mental Disorders, 4th. Edition Text Revision assessment as the reference standard.

Aim #3: To validate the ED-DTS in older ED patients. The ED-DTS will be performed by a clinical trials associate (CTA) and principal investigator in 200 ED patients that are > 65 years old. This instrument will be validated against a psychiatrist's Diagnostic and Statistical Manual of Mental Disorders, 4th. Edition Text Revision assessment as the reference standard.

Inclusion Criteria:

• 65 years of age or greater
• In the Emergency Department for less than 12 hour at the time of enrollment

Exclusion Criteria:

• Severe mental retardation or dementia
• Baseline communication barriers such as aphasia, deafness, blindness, or who are unable to speak English
• Refusal of consent
• Previous enrollment
• Comatose
• Out of the hospital before the assessments are completed

The participants will be those who are Vanderbilt University Emergency Department patients 65 years or older. There will be no selection bias in regards to race or gender. Only those who meet the inclusion/exclusion criteria will be considered for study inclusion.

This was a single center study and should be externally validated. Our findings cannot be generalized to those who are younger than 65 years old.