Validation and extension of the quick dementia rating system (QDRS).

Informant report dementia severity staging measures, such as the Quick Dementia Rating System (QDRS) offer clinicians useful diagnostic and staging information. These measures also potentially avoid many of the pitfalls inherent in mental status examinations (e.g., cultural bias, educational bias, floor and ceiling effects). We derive cut points for the QDRS and comprehensively examine their classification accuracy in a large, diagnostically heterogeneous, rural, memory disorder clinic sample. Our findings suggest the QDRS may be helpful when used in the context of a comprehensive diagnostic and staging evaluation. When used in isolation, the QDRS is insufficiently accurate for diagnosis and staging of dementia.