aCTD — Abbreviated Cognitive Test for Delirium

What this tool is and how to interpret its evidence

The Abbreviated Cognitive Test for Delirium, or aCTD, is a shortened version of the Cognitive Test for Delirium. It uses two of the parent instrument's nine content scores: a visual-attention measure and picture-recognition memory. Their scores are summed, with 10 or below classified positive at the published 10/11 cut point. It was designed to be more practical for intensive-care clinicians than the full CTD. The article does not give a stable completion-time estimate, and standardised cognitive-test administration remains necessary.

Hart and colleagues created the abbreviation through stepwise discriminant analysis of the original CTD validation sample, rather than by recruiting a new external cohort. The two-score total retained acceptable internal consistency and distinguished delirium from dementia, schizophrenia and depression. The current evidence extraction reports sensitivity of 94.7% and specificity of 98.8% in that 103-person source sample. Because both component selection and performance assessment used the same dataset, those figures are derivation results and likely optimistic until independently replicated.

aCTD is a genuine named CTD version but should not be counted as a separate instrument family. It also remains a cognitive test: a low score does not by itself demonstrate acute onset, fluctuation or a medical cause. The page should link to CTD and the primary paper, explain the two-component architecture, threshold and derivation design, and avoid copying the test stimuli or detailed scoring instructions. Sensory, language, motor and arousal limitations require clinical interpretation.