Background/aim: The diagnostic accuracy of brief informant screening instruments to detect dementia in critically ill adults is unknown. We sought to determine the diagnostic accuracy of the 2- to 3-min Ascertain Dementia 8 (AD8) completed by surrogates in detecting dementia among critically ill adults suspected of having pre-existing dementia by comparing it to the Clinical Dementia Rating Scale (CDR).
Methods: This substudy of BRAIN-ICU included a subgroup of 75 critically ill medical/surgical patients determined to be at medium risk of having pre-existing dementia (Informant Questionnaire on Cognitive Decline in the Elderly [IQCODE] score ≥3.3). We calculated the sensitivity, specificity, positive and negative predictive values (PPV and NPV), and AUC for the standard AD8 cutoff of ≥2 versus the reference standard CDR score of ≥1 for mild dementia.
Results: By the CDR, 38 patients had very mild or no dementia and 37 had mild dementia or greater. For diagnosing mild dementia, the AD8 had a sensitivity of 97% (95% CI 86-100), a specificity of 16% (6-31), a PPV of 53% (40-65), an NPV of 86% (42-100), and an AUC of 0.738 (0.626-0.850).
Conclusions: Among critically ill patients judged at risk for pre-existing dementia, the 2- to 3-min AD8 is highly sensitive and has a high NPV. These data indicate that the brief tool can serve to rule out dementia in a specific patient population.
Trial registration: ClinicalTrials.gov NCT00392795.
Keywords: Ascertain Dementia 8; Clinical Dementia Rating Scale; Cognitive disorders; Cognitive screening test; Critical illness; Delirium; Dementia; Diagnosis; Sensitivity; Specificity.
© 2020 S. Karger AG, Basel.