BackgroundNowadays, elderly patients represent a significant number of accesses to the Emergency Department (ED). Working rhythms do not allow to perform complete cognitive analysis, which would, however, be useful for the health care. This study aims to define the optimal cut-off values of the six-item Cognitive Impairment Test (6-CIT) as a cognitive screening tool in ED.MethodsThis study included 215 subjects, evaluated at the Emergency Department of the University Hospital of Monserrato, Cagliari, Italy, from July to December 2021. The accuracy of 6-CIT as a cognitive screening tool was assessed by comparison with Mini Mental State Examination (MMSE).ResultsThe correlation coefficient between the two tests was −0.836 (CI: −0.87 to −0.79; p < 0.0001), and 6-CIT showed AUC = 0.947 (CI: 0.908–0.973; p < 0.0001). The 8/9 6-CIT cut-off score presented 86.76% sensitivity (CI: 76.4–93.8) and 91.84% specificity (CI: 86.2–95.7), and Youden index for this score was 0.786.ConclusionOur study demonstrates that 6-CIT is a reliable cognitive screening tool in ED, offering excellent sensitivity and specificity with a 8/9 points cut-off score.