4AT

Bellelli G, Morandi A, Davis DHJ, et al. Validation of the 4AT, a new instrument for rapid delirium screening: a study in 234 hospitalised older people. The 4AT (alertness, AMT4, attention via months backward, acute change) took under 2 minutes, needed no special training, and had 89.7% sensitivity and 84.1% specificity for delirium.

SIGN 157 and NICE delirium guidance list the 4AT among recommended brief screening tools. Scoring: ≥ 4 suggests possible delirium ± cognitive impairment; 1–3 suggests possible cognitive impairment; 0 makes delirium (though not excluded) unlikely.