Delirium is missed in up to 75% of cases in the emergency department and inpatient settings because health care providers do not routinely screen for this syndrome. Several delirium assessments exist and have been reviewed by Wong et al. (Wong et al. JAMA. 2010). The Confusion Assessment Method (CAM) is probably the most well-known delirium assessment. Since that review has been published, however, several new delirium assessments have been developed and validated for the acute care setting.
The Delirium Triage Screen (DTS) is unique, two-component delirium assessment that was designed to rapidly rule out delirium in less than 20 seconds and reduces the number of formal delirium assessments needed by 50%. If the DTS is negative, then delirium is ruled out. If positive, a confirmatory, more specific delirium assessment is required to rule-in delirium. Depending on the clinical setting and resources available, the Brief Confusion Assessment Method (bCAM), 3D-CAM, Confusion Assessment Method for the Intensive Care Unit (CAM-ICU), CAM, or 4AT can be used to rule-in delirium.
Currently, the DTS, bCAM, CAM, and CAM-ICU have been evaluated in older emergency department patients. The DTS and bCAM are now part of the Geriatric Emergency Medicine Guidelines.
There is no one size fits all delirium assessment. In general, the more brief and simple the delirium assessment is, the less accurate it will be. In other words, diagnostic accuracy is usually sacrificed for brevity. There are also two primary types of delirium assessments: subjective and objective. Primarily subjective delirium assessments, such as the CAM, heavily rely upon clinical judgment and their diagnostic accuracy will be more dependent upon the rater’s level of experience and training. Primarily objective delirium assessments such as the bCAM, CAM-ICU, and 4AT incorporate objective testing with pre-specified cut-offs to help determine the presence or absence of some delirium features. While objective testing greatly increases ease of use and makes it less operator dependent, its diagnostic accuracy is likely to change in different patient populations (spectrum bias). The 3D-CAM is a unique delirium assessment since it has both subjective and objective components to determine each delirium feature.