Acute confusional syndrome (ACS), or delirium, is a neuropsychiatric disorder of attention and awareness with an acute onset and fluctuating course. It occurs in at least 20% of patients during the postoperative period of cardiac surgery and is associated with increased morbidity and mortality rates. However, it remains underdiagnosed in over half of cases. The 4 A’s Test, a recently introduced tool for ACS screening, comprises 4 items (alertness, Abbreviated Mental Test-4, attention, and acute change or fluctuating course) with a scoring range of 0-12 points; a score ≥4 suggests delirium. The test can be administered quickly (<2 minutes) by non-specialist personnel without prior training. However, no studies have yet established its diagnostic accuracy in cardiac surgery patients.

To address this, Chang et al. designed this single-center, prospective observational study in two phases, depending on whether the 4 A’s Test was administered once daily by research assistants (Phase 1, double-blind) or three times daily by the nursing staff (Phase 2). They included a cohort of 316 patients from St. Boniface Hospital (Canada) in their first three postoperative days on the ward following ICU discharge. The outcomes were then compared with the Confusion Assessment Method (CAM), routinely conducted three times daily by nursing staff, and with the reference standard based on the DSM-5 criteria. The secondary objective was to assess its predictive value for adverse surgical events, including mortality, postoperative complications, and hospital stay. Finally, they conducted a survey to gather nurses’ opinions on the 4 A’s Test implementation.

In Phase 1, a total of 137 patients were included, 24.8% of whom presented with ACS. The 4 A’s Test demonstrated an 85% sensitivity and 90% specificity, while the CAM showed a sensitivity of 23% and specificity of 100%. In Phase 2, nursing staff screened 179 patients, with an ACS prevalence of 13%. In this phase, the 4 A’s Test yielded a sensitivity of 58% and a specificity of 94%. Regarding patient outcomes, those with a positive 4 A’s Test had a hospital stay that was 2 days longer (p = .003), with no statistically significant differences in mortality or adverse events at 30 days. After implementing the 4 A’s Test, 64% of nurses felt it improved their confidence in detecting ACS, and 76% would consider its routine use.

The study concludes that the 4 A’s Test is an effective tool with moderate sensitivity and high specificity for detecting ACS in postoperative cardiac surgery patients in real-world clinical practice. It is recommended that its frequency be reduced to once daily to improve staff adherence and enhance early ACS detection.

COMMENTARY:

ACS is one of the most prevalent complications following cardiac surgery, with risk factors including extensive atherosclerotic disease, use of cardiopulmonary bypass for surgery, and the need for opioid analgesics. It is associated with a higher risk of mortality, hospital readmission, cognitive decline, and overall quality-of-life reduction. As ACS often has potentially treatable underlying causes (e.g., electrolyte imbalances, stroke, nosocomial infection, or adverse drug event), early diagnosis poses a challenge in the postoperative period of any cardiac surgery. Numerous screening tools have been developed for this purpose, some of which are validated in the ICU setting (e.g., CAM), yet none have shown proven effectiveness once patients are transferred to general wards.

A good screening test should not only have high sensitivity and specificity but should also be rapid, easy to administer, and reproducible. However, this study demonstrated that the test’s sensitivity was significantly reduced when administered by nursing staff, likely due to methodological inconsistencies and low adherence to test administration. Furthermore, ACS can manifest as hyperactive, hypoactive, or mixed forms, complicating initial detection by non-specialist staff in psychiatric diagnosis. One of the strengths of this study is its execution under real clinical conditions, with results reflecting the routine underestimation of neuropsychiatric evaluations and their complex prevalence. Notably, patients with prior neurocognitive deficits were not excluded, and the overall ACS prevalence aligns with other studies.

The authors themselves acknowledge several limitations, noting that in Phase 2, the results were not double-blinded since the same nurses conducted both tests. This study interestingly highlights that, when the 4 A’s Test was administered three times daily, the quality of the assessments decreased, impacting sensitivity results. Additionally, due to ACS’s fluctuating nature, it is possible that some phases of testing did not capture positive scores for ACS. Thus, given the workload burden on nursing staff, the authors recommend administering the test only once per day to optimize sensitivity and specificity and improve detection of a condition with potentially treatable causes.

While this study, due to its limited sample size and the inherent limitations of a single-center observational design, cannot provide sufficient validity to generalize its results to other centers, it lays the groundwork for future research to answer unresolved questions, such as whether early diagnosis improves patient outcomes, reducing morbidity and hospital stay.

REFERENCE:

Chang Y, Ragheb S, Oravec N, Kent D, Nugent K, Cornick A, et al. Diagnostic accuracy of the “4 A’s Test” delirium screening tool for the postoperative cardiac surgery ward. J Thorac Cardiovasc Surg 2023;165:1151-60. DOI: 10.1016/j.jtcvs.2021.05.031.