Validation of Two Screening Tools for Detecting Delirium in Older Patients in the Post-Anaesthetic Care Unit: A Diagnostic Test Accuracy Study

Abstract

(1) Background: Delirium is a common complication among surgical patients after major surgery, but it is often underdiagnosed in the post-anaesthetic care unit (PACU). Valid and reliable tools are required for improving diagnoses of delirium. The objective of this study was to evaluate the diagnostic test accuracy of the Three-Minute Diagnostic Interview for Confusion Assessment Method (3D-CAM) and the 4A’s Test (4AT) as screening tools for detection of delirium in older people in the PACU. (2) Methods: A prospective diagnostic test accuracy study was conducted in the PACU and surgical wards of a university-affiliated tertiary care hospital in Victoria, Australia. A consecutive prospective cohort of elective and emergency patients (aged 65 years or older) admitted to the PACU were recruited between July 2021 and December 2021 following a surgical procedure performed under general anaesthesia and expected to stay in the hospital for at least 24 h following surgery. The outcome measures were sensitivity, specificity positive predictive value and negative predictive value for 3D-CAM and 4AT. (3) Results: A total of 271 patients were recruited: 16.2% (44/271) had definite delirium. For a diagnosis of definite delirium, the 3D-CAM (area under curve (AUC) = 0.96) had a sensitivity of 100% (95% CI 92.0 to 100.0) in the PACU and during the first 5 days post-operatively. Specificity ranged from 93% (95% CI 87.8 to 95.2) to 91% (95% CI 85.9 to 95.2) in the PACU and during the first 5 days post-operatively. The 4AT (AUC = 0.92) had a sensitivity of 93% (95% CI 81.7 to 98.6) in the PACU and during the first 5 days post-operatively, and specificity ranged from 89% (95% CI 84.6 to 93.1) to 87% (95%CI 80.9 to 91.8) in the PACU and during the first 5 days post-operatively. (4) Conclusions: The 3D-CAM and the 4AT are sensitive and specific screening tools that can be used to detect delirium in older people in the PACU. Screening with either tool could have an important clinical impact by improving the accuracy of delirium detection in the PACU and hence preventing adverse outcomes associated with delirium.

4 AT Delirium Assessment Tool in Hospitalized Non-ICU Patients (≥65 Years): A Systematic Review on Validity and Reliability

“…In addition, it was found to improve delirium diagnosis [21], especially in older patients [36]. Moreover, it can be used in different departments, such as emergency units of various wards [34] and PACU [37]. However, the 4AT has a significant false-positive rate in this initial comparison, which may need further in-depth examinations [19].…”

“…Studies were reported from 10 different countries from Asia, Europe, Australia, and Canada (Fig. 2), including Iran [33], Canada [34], UK [21], Germany [35], Italy [36], Sewden [14], Norway [22], Australia [37], Spain [38] and Switzerland [19] (Fig. 2).…”

“…Other than sensitivity, specificity, and accuracy, the main benefit was the time taken to complete the 4AT assessment tool. As 4AT tool took 2-3 minutes, and other tools took 3.6 [37] and 12.46 [14] minutes to completion.…”

“…Study design, reference test was not blinded, generalizability. [37] Screening tools like the 3D-CAM and the 4AT may be utilized to identify delirium in the PACU's elderly population because of their high sensitivity and specificity.…”