Study 1 Overview (Oberhaus et al)
Objective: To compare the 3-Minute Diagnostic Confusion Assessment Method (3D-CAM) to the long-form Confusion Assessment Method (CAM) in detecting postoperative delirium.
Design: Prospective concurrent comparison of 3D-CAM and CAM evaluations in a cohort of postoperative geriatric patients.
Setting and participants: Eligible participants were patients aged 60 years or older undergoing major elective surgery at Barnes Jewish Hospital (St. Louis, Missouri) who were enrolled in ongoing clinical trials (PODCAST, ENGAGES, SATISFY-SOS) between 2015 and 2018. Surgeries were at least 2 hours in length and required general anesthesia, planned extubation, and a minimum 2-day hospital stay. Investigators were extensively trained in administering 3D-CAM and CAM instruments. Participants were evaluated 2 hours after the end of anesthesia care on the day of surgery, then daily until follow-up was completed per clinical trial protocol or until the participant was determined by CAM to be nondelirious for 3 consecutive days. For each evaluation, both 3D-CAM and CAM assessors approached the participant together, but the evaluation was conducted such that the 3D-CAM assessor was masked to the additional questions ascertained by the long-form CAM assessment. The 3D-CAM or CAM assessor independently scored their respective assessments blinded to the results of the other assessor.
Main outcome measures: Participants were concurrently evaluated for postoperative delirium by both 3D-CAM and long-form CAM assessments. Comparisons between 3D-CAM and CAM scores were made using Cohen κ with repeated measures, generalized linear mixed-effects model, and Bland-Altman analysis.
Main results: Sixteen raters performed 471 concurrent 3D-CAM and CAM assessments in 299 participants (mean [SD] age, 69 [6.5] years). Of these participants, 152 (50.8%) were men, 263 (88.0%) were White, and 211 (70.6%) underwent noncardiac surgery. Both instruments showed good intraclass correlation (0.98 for 3D-CAM, 0.84 for CAM) with good overall agreement (Cohen κ = 0.71; 95% CI, 0.58-0.83). The mixed-effects model indicated a significant disagreement between the 3D-CAM and CAM assessments (estimated difference in fixed effect, –0.68; 95% CI, –1.32 to –0.05; P = .04). The Bland-Altman analysis showed that the probability of a delirium diagnosis with the 3D-CAM was more than twice that with the CAM (probability ratio, 2.78; 95% CI, 2.44-3.23).
Conclusion: The high degree of agreement between 3D-CAM and long-form CAM assessments suggests that the former may be a pragmatic and easy-to-administer clinical tool to screen for postoperative delirium in vulnerable older surgical patients.
Study 2 Overview (Shenkin et al)
Objective: To assess the accuracy of the 4 ‘A’s Test (4AT) for delirium detection in the medical inpatient setting and to compare the 4AT to the CAM.
Design: Prospective randomized diagnostic test accuracy study.
Setting and participants: This study was conducted in emergency departments and acute medical wards at 3 UK sites (Edinburgh, Bradford, and Sheffield) and enrolled acute medical patients aged 70 years or older without acute life-threatening illnesses and/or coma. Assessors administering the delirium evaluation were nurses or graduate clinical research associates who underwent systematic training in delirium and delirium assessment. Additional training was provided to those administering the CAM but not to those administering the 4AT as the latter is designed to be administered without special training. First, all participants underwent a reference standard delirium assessment using Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV) criteria to derive a final definitive diagnosis of delirium via expert consensus (1 psychiatrist and 2 geriatricians). Then, the participants were randomized to either the 4AT or the comparator CAM group using computer-generated pseudo-random numbers, stratified by study site, with block allocation. All assessments were performed by pairs of independent assessors blinded to the results of the other assessment.
Main outcome measures: All participants were evaluated by the reference standard (DSM-IV criteria for delirium) and by either 4AT or CAM instruments for delirium. The accuracy of the 4AT instrument was evaluated by comparing its positive and negative predictive values, sensitivity, and specificity to the reference standard and analyzed via the area under the receiver operating characteristic curve. The diagnostic accuracy of 4AT, compared to the CAM, was evaluated by comparing positive and negative predictive values, sensitivity, and specificity using Fisher’s exact test. The overall performance of 4AT and CAM was summarized using Youden’s Index and the diagnostic odds ratio of sensitivity to specificity.
Results: All 843 individuals enrolled in the study were randomized and 785 were included in the analysis (23 withdrew, 3 lost contact, 32 indeterminate diagnosis, 2 missing outcome). Of the participants analyzed, the mean age was 81.4 [6.4] years, and 12.1% (95/785) had delirium by reference standard assessment, 14.3% (56/392) by 4AT, and 4.7% (18/384) by CAM. The 4AT group had an area under the receiver operating characteristic curve of 0.90 (95% CI, 0.84-0.96), a sensitivity of 76% (95% CI, 61%-87%), and a specificity of 94% (95% CI, 92%-97%). In comparison, the CAM group had a sensitivity of 40% (95% CI, 26%-57%) and a specificity of 100% (95% CI, 98%-100%).
Conclusions: The 4AT is a pragmatic screening test for delirium in a medical space that does not require special training to administer. The use of this instrument may help to improve delirium detection as a part of routine clinical care in hospitalized older adults.