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 MBT-Vigilance 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.