Diagnosis of postoperative delirium in older adults using the Confusion Assessment Method for the intensive care unit in non-intensive care unit settings: A test modification might improve its diagnostic performance.

Abstract

To evaluate the diagnostic performance of the Confusion Assessment Method for the intensive care unit (CAM-ICU) among postoperative older patients in non-ICU settings. The CAM-ICU was used by trained staff to prospectively evaluate postoperative patients for delirium. The patients were aged ≥60 years, were in general wards and had no critical illnesses. The assessments occurred for 7 consecutive days after surgery. The results were compared with delirium diagnoses obtained by geriatricians using Diagnostic and Statistical Manual of Mental Disorders 5th edition criteria as the reference standard. The sensitivity of delirium detection for the CAM-ICU was 31.6% (95% confidence interval [CI] 12.6-56.6), while the specificity was 97.6% (95% CI 94.9-99.1), positive predictive value was 50.0% (95% CI 26.3-73.7) and negative predictive value was 95.0% (95% CI 93.3-96.3). Feature 4 (disorganized thinking) yielded the highest sensitivity (60%; 95% CI 14.7-94.7), whereas feature 2 (inattention) had low sensitivity (36.8%; 95% CI 16.3-61.6). Further analyses to explore the highest sensitive criteria showed that if CAM-ICU diagnoses were made by the presence of any two out of feature 1 (acute change or fluctuation of cognition), feature 3 (altered level of consciousness) or feature 4, the sensitivity increased substantially to 80.0% (95% CI 28.4-99.5), with a reasonably high specificity of 81.8% (95% CI 48.2-97.7). Modification of the flow of delirium diagnosis using the CAM-ICU appears to offer a better sensitivity for detecting delirium in non-ICU settings. Furthermore, changing feature 2 to evaluate patients' attention levels over a longer period of time might yield a better diagnostic performance. Geriatr Gerontol Int 2019; 19: 762-767.