Dementia staging across three different methods.

BACKGROUND/AIMS: To investigate the effectiveness of an item response theory (IRT)-based approach to staging dementia.
METHODS: IRT estimates of dementia severity in 1,485 patients were used to stage dementia and then compared to dementia staging using the classic Clinical Dementia Rating Scale (CDR) algorithm and the Sum of the Boxes (SOB) approach.
RESULTS: Measurement imprecision was highest when dementia stages were determined based on the classic algorithm (48% of sample), lower when they were determined based on the SOB approach (12%), and lowest when determined using IRT-based staging (0%).
CONCLUSION: The classic CDR algorithm weights boxes largely according to clinical experience. The SOB approach weights all boxes equally. The IRT approach weights boxes according to their actual ability to identify dementia severity and therefore provides the most precise information for staging dementia.