Validation of the 6-Item Cognitive Impairment Test and the 4AT test for combined delirium and dementia screening in older Emergency Department attendees

Background screening for cognitive impairment in Emergency Department (ED) requires short, reliable tools. Objective to validate the 4AT and 6-Item Cognitive Impairment Test (6-CIT) for ED dementia and delirium screening. Design diagnostic accuracy study. Setting/subjects attendees aged ≥70 years in a tertiary care hospital's ED. Methods trained researchers assessed participants using the Standardised Mini Mental State Examination, Delirium Rating Scale-Revised 98 and Informant Questionnaire on Cognitive Decline in the Elderly, informing ultimate expert diagnosis using Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria for dementia and delirium (reference standards). Another researcher blindly screened each participant, within 3 h, using index tests 4AT and 6-CIT. Result of 419 participants (median age 77 years), 15.2% had delirium and 21.5% had dementia. For delirium detection, 4AT had positive predictive value (PPV) 0.68 (95% confidence intervals: 0.58-0.79) and negative predictive value (NPV) 0.99 (0.97-1.00). At a pre-specified 9/10 cut-off (9 is normal), 6-CIT had PPV 0.35 (0.27-0.44) and NPV 0.98 (0.95-0.99). Importantly, 52% of participants had no family present. A novel algorithm for scoring 4AT item 4 where collateral history is unavailable (score 4 if items 2-3 score ≥1; score 0 if items 1-3 score is 0) proved reliable; PPV 0.65 (0.54-0.76) and NPV 0.99 (0.97-1.00). For dementia detection, 4AT had PPV 0.39 (0.32-0.46) and NPV 0.94 (0.89-0.96); 6-CIT had PPV 0.46 (0.37-0.55) and NPV 0.94 (0.90-0.97). Conclusion 6-CIT and 4AT accurately exclude delirium and dementia in older ED attendees. 6-CIT does not require collateral history but has lower PPV for delirium.