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.