Abstract

BACKGROUND: The Clinical Dementia Rating (CDR) and CDR Sum-of-Boxes can be used to grade mild but clinically important cognitive symptoms of Alzheimer disease. However, sensitive clinical interview formats are lengthy.
OBJECTIVES: To develop a brief instrument for obtaining CDR scores and to assess its reliability and cross-sectional validity.
METHODS: Using legacy data from expanded interviews conducted among 347 community-dwelling older adults in a longitudinal study, we identified 60 questions (from a possible 131) about cognitive functioning in daily life using clinical judgment, inter-item correlations, and principal components analysis. Items were selected in 1 cohort (n=147), and a computer algorithm for generating CDR scores was developed in this same cohort and re-run in a replication cohort (n=200) to evaluate how well the 60 items retained information from the original 131 items. Short interviews based on the 60 items were then administered to 50 consecutively recruited older individuals, with no symptoms or mild cognitive symptoms, at an Alzheimer's Disease Research Center. Clinical Dementia Rating scores based on short interviews were compared with those from independent long interviews.
RESULTS: In the replication cohort, agreement between short and long CDR interviews ranged from κ=0.65 to 0.79, with κ=0.76 for Memory, κ=0.77 for global CDR, and intraclass correlation coefficient for CDR Sum-of-Boxes=0.89. In the cross-sectional validation, short interview scores were slightly lower than those from long interviews, but good agreement was observed for global CDR and Memory (κ≥0.70) as well as for CDR Sum-of-Boxes (intraclass correlation coefficient=0.73).
CONCLUSION: The Structured Interview & Scoring Tool-Massachusetts Alzheimer's Disease Research Center is a brief, reliable, and sensitive instrument for obtaining CDR scores in persons with symptoms along the spectrum of mild cognitive change.