Detection of Delirium in Hospitalized Older General Medicine Patients: A Comparison of the 3D-CAM and CAM-ICU

Abstract

Background: Delirium is common in older hospitalized patients and is associated with poor outcomes, yet most cases go undetected. The best approach for systematic delirium identification outside the intensive care unit remains unknown.

Objective: To conduct a comparative effectiveness study of the Confusion Assessment Method for the ICU (CAM-ICU) and the newly developed 3-minute diagnostic assessment for delirium using the Confusion Assessment Method (3D-CAM) in general medicine inpatients.

Design: Cross-sectional comparative effectiveness study.

Setting: Two non-intensive care general medicine units at a single academic medical center.

Participants: Hospitalized general medicine patients aged ≥75 years.

Measurements: Clinicians performed a reference standard assessment for delirium that included patient interviews, family interviews, and review of the medical record. An expert panel determined the presence or absence of delirium using DSM-IV criteria. Two blinded research assistants administered the CAM-ICU and the 3D-CAM in random order, and we determined their diagnostic test characteristics compared to the reference standard.

Results: Among the 101 participants (mean age 84 ± 5.5 years, 61 % women, 25 % with dementia), 19 % were classified as delirious based on the reference standard. Evaluation times for the 3D-CAM and CAM-ICU were similar. The sensitivity [95 % confidence interval (CI)] of delirium detection for the 3D-CAM was 95 % [74 %, 100 %] and for the CAM-ICU was 53 % [29 %, 76 %], while specificity was >90 % for both instruments. Subgroup analyses showed that the CAM-ICU had sensitivity of 30 % in patients with mild delirium vs. 100 % for the 3D-CAM.

Conclusions: In this comparative effectiveness study, we found that the 3D-CAM had substantially higher sensitivity than the CAM-ICU in hospitalized older general medicine patients, and similar administration time. Therefore, the 3D-CAM may be a superior screening tool for delirium in this patient population.

Keywords: delirium; dementia; diagnosis; inpatient; screening.

Figure 1

Study Recruitment and Design. Here the overall study flow is depicted. Eligible patients aged 75 or older admitted to the general medicine service of a large teaching hospital were approached for consent, and 201 patients were enrolled. Of these, 101 participated in this study comparing the 3D-CAM and CAM-ICU. All patients underwent a reference standard delirium assessment by an experienced clinician. Within 2 h of this assessment, they underwent two additional brief assessments, the 3D-CAM and the CAM-ICU, administered in random order, which were performed by trained research assistants blinded to the reference standard assessment and to each other's results.