Use the Short Blessed Test to rule it out in under two minutes: Download Here
Another extremely busy day, but you feel a small sense of achievement as you prepare to discharge an 87-year old man with mild lower leg cellulitis. Your euphoria quickly evaporates as the nurse tells you that several family members are concerned that the patient has recently been demonstrating increasing signs of cognitive dysfunction. After talking briefly with the family, you can’t help but wonder (to yourself) why they are bringing this to your attention now rather than bringing it to the attention of the patient’s primary care physician (PCP).
- Acknowledge the family’s concern and advise follow-up with the PCP
- Initiate a full delirium work-up with the intention of making this Dr. Somebody Else’s problem.
- Quickly assess the patient for cognitive dysfunction and modify the management plans as needed.
The Critical Question:
Is there a brief bedside test that can reliably rule in or rule out cognitive impairment in the elderly?
Four Sensitive Screening Tools to Detect Cognitive Dysfunction in Geriatric Emergency Department Patients: Brief Alzheimer’s Screen, Short Blessed Test, Ottawa3DY, and the Caregiver Administered AD8, Acad Emerg Med 2011; 18(4): [pages TBD].
The Bottom Line
There are three brief performance-based screening instruments to identify geriatric patients with cognitive dysfunction more rapidly than the MMSE. These are the Ottawa 3DY (O3DY), the Brief Alzheimer’s Screen (BAS), and the Short Blessed Test (SBT). Of the three, the SBT provides the best diagnostic test characteristics and overlap with MMSE results.
The term cognitive dysfunction, although very nonspecific, typically includes mild cognitive impairment (MCI), delirium, and dementia. Delirium, a transient disorder of mental capabilities, is a symptom of an acute medical illness and, therefore, considered a true medical emergency. MCI refers to decline in memory, language, or other cognitive functions and is often considered early Alzheimer’s Disease that does not otherwise impair daily living. Dementia is a more serious form of cognitive decline resulting in problems with memory, judgment, orientation, and executive functioning. While neither MCI nor dementia is an immediate threat to morbidity or mortality, dementia is a proven independent predictor of functional decline, and institutionalization. Of direct interest to us is that it also has been proven to be an independent predictor of return visit post-ED discharge. In fact, this issue has been deemed important enough that the assessment of cognitive dysfunction has recently been incorporated as a minimal core competency for emergency medicine residents and a quality indicator for all ED providers.
The current evidence shows that we don’t do well at identifying patients with cognitive dysfunction. In fact, emergency providers miss up to 70% of patients with a Mini-Mental Status Exam (MMSE) ≤ 23. The MMSE can be time consuming to apply and has not been recommended to use for the diagnosis of MCI, which requires specific tests. A number of simple screening instruments have been tested in the ED, but none have met the necessary performance characteristics needed to be of clinical value. The time pressures we face might play a role in our poor performance at identifying cognitive impairment. Ideally, we would be able to perform a bedside clinical test that is simple and has a high inter-rater reliability meaning that we all arrive at the same score when we each apply it on the same patient. And finally, and perhaps most importantly, the test must have the ability to accurately discriminate those with cognitive dysfunction from those without.
A recent study had trained research assistants test patients using the O3DY, BAS, and SBT. Each patient’s results were compared to their responses to the MMSE for which a score of less than or equal to 23 was the criterion standard for cognitive dysfunction. All enrolled subjects were non-critically ill, English-speaking adults over age 65-years and had not received any sedating medications prior to or during the testing. The investigators calculated the sensitivity, specificity, likelihood ratios, and receiver operating curve area under the curve (AUC). They also created Venn diagrams to quantitatively compare the degree of overlap amongst positive test results between the instruments.
A total of 163 patients were enrolled and the prevalence of cognitive dysfunction was 37% which included 5.5% with delirium and 3% with self-reported dementia. The SBT, BAS, and O3DY each had sensitivity of 95% with specificities of 65%, 52% and 51% respectively. The SBT also demonstrated the best likelihood ratios of 2.1 and 0.08 and an AUC similar to the BAS of 0.93.
This is a single center observational cohort study on a convenience sample of patients that provides an important first step in practice-changing information. Subsequent studies will need to validate the results, but the challenge will be finding a reference standard by which to compare the SBT and other ED-friendly instruments. This study justifiably used the MMSE, but this test has shown increased false-positive rates in poorly educated and lower socio-economic populations and increased false-negative rates in those with higher levels of education. These flaws mean that the MMSE is less than a ‘gold’ standard.
Finally, once validated as an adequate brief cognitive function screening tests, their application will need to be demonstrated as improving patient outcomes and this is best done through a randomized controlled trial.
Of the three brief performance-based screening instruments: SBT, BAS, and O3DY to identify geriatric patients with cognitive dysfunction more rapidly than the MMSE, the SBT provides the best diagnostic test performance.
You take a few minutes to apply the SBT to your elderly patient. His score is 3/28 indicating normal cognition. Given the high sensitivity of the test to rule out cognitive dysfunction, you’re confident in this result and reassure the family. You also advise them that more specific testing for mild cognitive impairment.