Reliability of the Alzheimer’s Disease Assessment Scale (ADAS-Cog) in longitudinal Studies

Title:Reliability of the Alzheimer’s Disease Assessment Scale (ADAS-Cog) in longitudinal Studies

Volume: 10 Issue: 9

Author(s): Anzalee Khan, Christian Yavorsky, Guillermo DiClemente, Mark Opler, Stacy Liechti, Brian Rothman and Sofija Jovic

Affiliation:

Keywords: Reliability, Alzheimer’s disease, data monitoring.

Abstract: Background: Considering the scarcity of longitudinal assessments of reliability, there is need for a more precise understanding of cognitive decline in Alzheimer’s Disease (AD). The primary goal was to assess longitudinal changes in inter-rater reliability, test retest reliability and internal consistency of scores of the ADAS-Cog.

Methods: 2,618 AD subjects were enrolled in seven randomized, double-blind, placebo-controlled, multicenter-trials from 1986 to 2009. Reliability, internal-consistency and cross-sectional analysis of ADAS-Cog and MMSE across seven visits were examined.

Results: Intra-class correlation (ICC) for ADAS-Cog was moderate to high supporting their reliability. Absolute Agreement ICCs 0.392 (Visit-7) to 0.806 (Visit-2) showed a progressive decrease in correlations across time. Item analysis revealed a decrease in item correlations, with the lowest correlations for Visit 7 for Commands (ICC=0.148), Comprehension (ICC=0.092), Spoken Language (ICC=0.044).

Discussion: Suitable assessment of AD treatments is maintained through accurate measurement of clinically significant outcomes. Targeted rater education ADAS-Cog items over-time can improve ability to administer and score the scale.

Cite this article as:

Khan Anzalee, Yavorsky Christian, DiClemente Guillermo, Opler Mark, Liechti Stacy, Rothman Brian and Jovic Sofija, Reliability of the Alzheimer’s Disease Assessment Scale (ADAS-Cog) in longitudinal Studies, Current Alzheimer Research 2013; 10 (9) . https://dx.doi.org/10.2174/15672050113106660160