Active case finding of dementia in ambulatory care settings: a comparison of three strategies

To reduce the diagnostic gap of dementia, three strategies can be employed for case finding of cognitive impairment in ambulatory care settings, namely using informant report, brief cognitive test or a combination of informant report and brief cognitive test. The right strategy to adopt across different healthcare settings remains unclear. This diagnostic study compared the performance of the three strategies for detecting dementia (primary aim), as well as for detecting both mild cognitive impairment (MCI) and dementia (secondary aim).

Participants aged ≥65 years (n = 11 057) were recruited from Alzheimer's Disease Centers across the USA. Participants provided data on an informant report (Functional Activities Questionnaire), brief cognitive test (four-item short variant of Montreal Cognitive Assessment) and a combined measure with informant report and brief cognitive test (sum of Functional Activities Questionnaire and Montreal Cognitive Assessment short variant). They also received standardized assessments (clinical history, physical examination and neuropsychological testing) to diagnose MCI and dementia. Areas under the receiver operating characteristic curve (AUCs) of the three strategies were compared using the DeLong method, with AUC > 90% indicating excellent performance.

All three strategies had excellent performance in detecting dementia, although informant report [AUC, 95.9%; 95% confidence intervals (CI), 95.4-96.3%] was significantly better than brief cognitive test (AUC, 93.0%; 95% CI, 92.4-93.6%) and the combined measure had the best performance (AUC, 97.0%; 95% CI, 96.7-97.4%). However, to detect both MCI and dementia, only the combined measure had excellent performance (AUC, 93.0%; 95% CI, 92.5-93.4%), whereas stand-alone informant report or brief cognitive test performed suboptimally (AUC < 90%). Performance of the three strategies was not affected by participants' age, educational attainment or underlying prevalence of MCI and dementia.

For case finding of dementia in ambulatory care settings, informant reports would suffice as first-line measures and brief cognitive tests may optionally be added on, in services with available resources, to further improve the accuracy of detection. For case finding of both MCI and dementia, a combination of informant reports and brief cognitive tests remains the most appropriate strategy.