The Clinical Dementia Rating scale (CDR) is a subjectively rated clinician-reported outcome measure, used as a sole primary endpoint in clinical trials of early symptomatic Alzheimer’s disease (AD).

The CDR is also a key secondary endpoint that contributes to diagnostic classification in prevention trials for time-to event analyses, and also used as a co- primary endpoint in some trials of mild to moderate dementia due to AD1 .

Scoring the CDR can be challenging, particularly in mild disease; rater administration and scoring errors are common.

The goal of this study was to identify a CDR quality metric, based upon internal patterns of domain scores that could be used to identify atypical patterns that might be indicative of scoring errors.