Diagnostic accuracy of the "4 A's Test" delirium screening tool for the postoperative cardiac surgery ward.

Abstract Background Delirium is prevalent and underdetected among cardiac surgery patients on the postoperative ward. This study aimed to validate the 4 A's Test delirium screening tool and evaluate its accuracy both when used by research assistants and when subsequently implemented by nursing staff on the ward. Methods This single-center, prospective observational study evaluated the performance of the 4 A's Test administered by research assistants (phase 1) and nursing staff (phase 2). Assessments were undertaken during the patients' first 3 postoperative days on the postcardiac surgery ward along with previous routine nurse-led Confusion Assessment Method assessments. These index tests were compared with a reference standard diagnosis of delirium based on Diagnostic and Statistical Manual of Mental Disorders 5th Edition criteria. Surveys regarding delirium screening were administered to nurses pre- and postimplementation of the 4 A's Test in phase 2 of the study. Results In phase 1, a total of 137 patients were enrolled, of whom 24.8% experienced delirium on the postoperative cardiac ward. The 4 A's Test had a sensitivity of 85% (95% confidence interval, 73-93) and a specificity of 90% (95% confidence interval, 85-93) compared with the reference standard. The nurse-assessed Confusion Assessment Method had a sensitivity of 23% (95% confidence interval, 13-37) and specificity of 100% (95% confidence interval, 99-100). In phase 2, nurses (n = 51) screened 179 patients for delirium using the 4 A's Test. Compared with the reference rater, the 4 A's Test had a sensitivity of 58% (95% confidence interval, 28-85) and specificity of 94% (95% confidence interval, 85-98). Postimplementation, 64% of nurses thought that the 4 A's Test improved their confidence in delirium detection, and 76% of nurses would consider routine 4 A's Test use. Conclusions The 4 A's Test demonstrated moderate sensitivity and high specificity to detect delirium in a real-world setting after cardiac surgery on the postoperative ward. A modified model of use with less frequent administration, along with increased engagement of the postoperative team, is recommended to improve early delirium detection on the cardiac surgery postoperative ward.