Interrater reliability of the Clinical Dementia Rating in a multicenter trial.

Objective: To test the interrater reliability of the Clinical Dementia Rating (CDR) in a multicenter clinical trial.

Design: Observational study.

Setting: Training session for a multicenter trial of milameline, a direct muscarinic agonist, in the treatment of Alzheimer's disease.

Participants: Twenty-four raters (physicians and nurses) familiar with drug trials and expert in the care of patients with Alzheimer's disease.

Methods: Independent scoring of the CDR using four videotaped CDR interviews.

Outcome Measure: Interrater reliability, as tested by the Kappa statistic

Results: The overall interrater reliability was 0.62. Within the CDR domains, the global kappas ranged from 0.33 +/- 0.06 to 0.88 +/- 0.06.

Conclusions: The data support moderate to high overall interrater reliability but show important difficulties in the reliable assessment of early dementia.