Usefulness of the 4A's test for detecting delirium in critically ill patients: a multicenter prospective observation study

The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) is a robust and reliable instrument for discerning delirium within the specific context of the intensive care unit (ICU). Nonetheless, the CAM-ICU is burdened by various limitations, including a protracted learning curve and the need for frequent daily administration. The 4 A's Test (4AT) was formulated to assess delirium in hospitalized patients and may have distinct advantages over the CAM-ICU, particularly regarding practical applicability within the ICU bundle. This study was performed to assess the utility of the 4AT in detecting delirium in critically ill patients. This multicenter prospective observational study involved critically ill patients at four academic tertiary care hospitals in South Korea from June 2021 to September 2022. In total, 274 patients (median age, 64 years; 56.9% men) were included, and 75 (27.4%) developed delirium. The 4AT showed good performance in detecting ICU delirium (area under the curve, 0.879; P < 0.001). The 4AT showed a sensitivity of 74.0%, specificity of 95.4%, positive predictive value of 77.5%, negative predictive value of 94.6%, and accuracy of 91.7% for ICU detection of delirium. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the CAM-ICU for detecting ICU delirium were 71.3%, 97.1%, 83.8%, 94.1%, and 92.6%, respectively. The 4AT showed acceptable reliability and validity for detecting ICU delirium in critically ill patients. Because the 4AT is simpler and easier to learn, this scale could be a useful alternative to the CAM-ICU for detecting delirium in critically ill patients.