Evaluation of delirium screening tools in geriatric medical inpatients: a diagnostic test accuracy study

screening all unscheduled older adults for delirium is recommended in national guidelines, but there is no consensus on how to perform initial assessment.

to evaluate the test accuracy of five brief cognitive assessment tools for delirium diagnosis in routine clinical practice.

a consecutive cohort of non-elective, elderly care (older than 65 years) hospital inpatients admitted to a geriatric medical assessment unit of an urban teaching hospital. Reference assessments were clinical diagnosis of delirium performed by elderly care physicians. Routine screening tests were: Abbreviated Mental Test (AMT-10, AMT-4), 4 A's Test (4AT), brief Confusion Assessment Method (bCAM), months of the year backwards (MOTYB) and informant Single Question in Delirium (SQiD).

we assessed 500 patients, mean age 83 years (range = 66-101). Clinical diagnoses were: 93 of 500 (18.6%) definite delirium, 104 of 500 (20.8%) possible delirium and 277 of 500 (55.4%) no delirium; 266 of 500 (53.2%) were identified as definite or possible dementia. For diagnosis of definite delirium, AMT-4 (cut-point < 3/4) had a sensitivity of 92.7% (95% confidence interval (CI): 84.8-97.3), with a specificity of 53.7% (95% CI: 48.1-59.2); AMT-10 (<4/10), MOTYB (<4/12) and SQiD showed similar performance. bCAM had a sensitivity of 70.3% (95% CI: 58.5-80.3) with a specificity of 91.4% (95% CI: 87.7-94.3). 4AT (>4/12) had a sensitivity of 86.7% (95% CI: 77.5-93.2) and specificity of 69.5% (95% CI: 64.4-74.3).

short screening tools such as AMT-4 or MOTYB have good sensitivity for definite delirium, but poor specificity; these tools may be reasonable as a first stage in assessment for delirium. The 4AT is feasible and appears to perform well with good sensitivity and reasonable specificity.