Abstract
Background: The Alzheimer's Disease Assessment Scale - Cognitive Behavior section (ADAS-Cog) is the most commonly used cognitive test in AD clinical trials. However, there are concerns about its use in early-stage disease. Herein we examine those concerns using traditional psychometric methods. Methods: We analyzed ADAS-Cog data (n = 675) based on six psychometric properties: data completeness; scaling assumptions; targeting; reliability; validity; and responsiveness. Results: At the scale-level, criteria tested for data completeness, scaling assumptions (item total correlations 0.33-0.59), targeting (no floor/ceiling effects), reliability (Cronbach's α = 0.74), and validity (correlation with MMSE = -0.70) were satisfied. Responsiveness (baseline to 12 months; n = 145) was moderate to high (effect size = -0.73). However, 8 of 11 ADAS-Cog components had substantial ceiling effects (range 32%-83%), and decreased responsiveness associated with low to moderate effect sizes (0.14-0.65). Conclusion: In our study, many patients with AD found large portions of the ADAS-Cog too easy. Future research should consider modifying the ADAS-Cog or developing a new test.
Original language | English (US) |
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Pages (from-to) | S10-S20 |
Journal | Alzheimer's and Dementia |
Volume | 9 |
Issue number | 1 SUPPL. |
DOIs | |
State | Published - Feb 2013 |
Keywords
- Alzheimer's disease
- Clinical trials
- Psychometrics
- Reliability
- Validity
ASJC Scopus subject areas
- Epidemiology
- Health Policy
- Developmental Neuroscience
- Clinical Neurology
- Geriatrics and Gerontology
- Psychiatry and Mental health
- Cellular and Molecular Neuroscience