Comparison of novel tools with traditional cognitive tests in detecting delirium in elderly medical patients

BACKGROUND Efficient detection of delirium and comorbid delirium-dementia is a key diagnostic challenge.Development of new,efficient delirium-focused methods of cognitive assessment is a key challenge for improved detection of neurocognitive disorders in everyday clinical practice.AIM To compare the accuracy of two novel bedside tests of attention,vigilance and visuospatial function with conventional bedside cognitive tests in identifying delirium in older hospitalized patients.METHODS 180 consecutive elderly medical inpatients(mean age 79.6±7.2;51%female)referred to a psychiatry for later life consultation-liaison service with delirium,dementia,comorbid delirium-dementia and cognitively intact controls.Participants were assessed cross-sectionally with conventional bedside cognitive tests[WORLD,Months Backward test(MBT),Spatial span,Vigilance A and B,Clock Drawing test and Interlocking Pentagons test]and two novel cognitive tests[Lighthouse test,Letter and Shape Drawing test(LSD)-4].RESULTS Neurocognitive diagnoses were delirium(n=44),dementia(n=30),comorbid delirium-dementia(n=60)and no neurocognitive disorder(n=46).All conventional tests had sensitivity of>70%for delirium,with best overall accuracy for the Vigilance-B(78.3%),Vigilance-A(77.8%)and MBT(76.7%)tests.The sustained attention component of the Lighthouse test was the most distinguishing of delirium(sensitivity 84.6%;overall accuracy 75.6%).The LSD-4 had sensitivity of 74.0%and overall accuracy 74.4%for delirium identification.Combining tests allowed for enhanced sensitivity(>90%)and overall accuracy(≥75%)with the highest overall accuracy for the combination of MBT-Vigilance A and the combined Vigilance A and B tests(both 78.3%).When analyses were repeated for those with dementia,there were similar findings with the MBTVigilance A the most accurate overall combination(80.0%).Combining the Lighthouse-SA with the LSD-4,a fail in either test had sensitivity for delirium of 91.4 with overall accuracy of 74.4%.CONCLUSION Bedside tests of attention,vigilance and visuospatial ability can help to distinguish neurocognitive disorders,including delirium,from other presentations.The Lighthouse test and the LSD-4 are novel tests with high accuracy for detecting delirium.

Months backward test:A review of its use in clinical studies

AIM: To review the use of the Months Backwards Test(MBT) in clinical and research contexts.METHODS: We conducted a systematic review of reports relating to the MBT based upon a search of Psych INFO and MEDLINE between January 1980 and December 2014. Only reports that specifically described findings pertaining to the MBT were included. Findings were considered in terms of rating procedures, testing performance, psychometric properties, neuropsychological studies and use in clinical populations.RESULTS: We identified 22 data reports. The MBT is administered and rated in a variety of ways with very little consistency across studies. It has been used to assess various cognitive functions including focused and sustained attention as well as central processingspeed. Performance can be assessed in terms of the ability to accurately complete the test without errors("MB accuracy"), and time taken to complete the test("MB duration"). Completion time in cognitively intact subjects is usually < 20 s with upper limits of 60-90 s typically applied in studies. The majority of cognitively intact adults can complete the test without error such that any errors of omission are strongly suggestive of cognitive dysfunction. Coverage of clinical populations, including those with significant cognitive difficulties is high with the majority of subjects able to engage with MBT procedures. Performance correlates highly with other cognitive tests, especially of attention, including the digit span backwards, trailmaking test B, serial threes and sevens, tests of simple and complex choice reaction time, delayed story recall and standardized list learning measures. Test-retest and inter-rater reliability are high(both > 0.90). Functional magnetic resonance imaging studies comparing the months forward test and MBT indicate greater involvement of more complex networks(bilateral middle and inferior frontal gyri, the posterior parietal cortex and the left anterior cingulate gyrus) for backwards cognitive processing. The MBT has been usefully applied to the study of a variety of clinical presentations, for both cognitive and functional assessment. In addition to the assessment of major neuropsychiatric conditions such as delirium, dementia and Mild Cognitive Impairment, the MBT has been used in the assessment of concussion, profiling of neurocognitive impairments in organic brain disorders and Parkinson's disease, prediction of delirium risk in surgical patients and medication compliance in diabetes. The reported sensitivity for acute neurocognitive disturbance/delirium in hospitalised patients is estimated at 83%-93%. Repeated testing can be used to identify deteriorating cognitive function over time.CONCLUSION: The MBT is a simple, versatile tool that is sensitive to significant cognitive impairment. Performance can be assessed according to accuracy and speed of performance. However, greater consistency in administration and rating is needed. We suggest two approaches to assessing performance- a simple(pass/fail) method as well as a ten point scale for rating test performance(467).