Screening for delirium after surgery: validation of the 4 A's test (4AT) in the post‐anaesthesia care unit

Abstract

Summary Postoperative delirium is common and has multiple adverse consequences. Guidelines recommend routine screening for postoperative delirium beginning in the post‐anaesthesia care unit. The 4 A's test (4AT) is a widely used assessment tool for delirium but there are no studies evaluating its use in the post‐anaesthesia care unit. We evaluated the performance of the 4AT in the post‐anaesthesia care unit in a tertiary German medical centre. Adults who were able to provide informed consent, were not scheduled for postoperative intensive care, and who did not have dementia or severe neuropsychiatric disorders underwent screening by trained research staff with the Nurse Delirium Screening Scale and a new German translation of the 4AT in a random order at the point of discharge from the post‐anaesthesia care unit. Reference standard assessment of delirium was psychiatric evaluation by experienced clinicians. Five hundred and forty‐three patients (mean age (SD) 52 (18) years) were analysed; 22 (4.1%) patients developed delirium. The sensitivity and specificity of the 4AT were 95.5% (95%CI 77.2–99.9) and 99.2% (95%CI 98.1–99.8), respectively. The area under the receiver operator characteristic curve was 0.998 (95%CI 0.995–1.000). The Nursing Delirium Screening Scale had a sensitivity of 27.3% (95%CI 10.7–50.2) and specificity of 99.4% (95%CI 98.3–99.9), with an area under the curve of 0.761 (95%CI 0.629–0.894). These findings suggest that the 4AT is an effective and robust instrument for delirium detection in the post‐anaesthesia care unit.

Diagnostic Test Accuracy of the 4AT for Delirium Detection: A Systematic Review and Meta-Analysis

“…Among them, we excluded 57 studies, 2 of which were validation studies of the 4AT using the same dataset with already included studies [ 23 , 24 ]. As a result, a total of 13 articles that met the inclusion criteria were finally identified in our systematic review [ 10 , 11 , 12 , 20 , 21 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

Diagnostic test accuracy of the Nursing Delirium Screening Scale: A systematic review and meta‐analysis

“…Among them, four studies reported various cut-off scores for the DTA of the Nu-DESC (Hargrave et al, 2017;Leung et al, 2008;Neufeld et al, 2013;Saller et al, 2019; Table 3).…”

The 4AT – an instrument for delirium detection for older patients in the post‐anaesthesia care unit

“…It contains the four‐item Abbreviated Mental Test (AMT4: age, date of birth, current year and place), evidence of acute change or fluctuation, alertness and the month backwards test for assessing attention. In a recent study, we evaluated an adult cohort of 543 patients aged between 18 and 96 years and found excellent performance of the 4AT to diagnose delirium in the recovery area in a tertiary German medical centre . In order to examine the properties of the 4AT to diagnose delirium in older patients in this setting, we subsequently analysed a subset of 143 patients from the original study that were 65 years or older.…”