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Putting the Alzheimer's cognitive test to the test I: Traditional psychometric methods
Author(s) -
Hobart Jeremy,
Cano Stefan,
Posner Holly,
Selnes Ola,
Stern Yaakov,
Thomas Ronald,
Zajicek John
Publication year - 2013
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2012.08.005
Subject(s) - cronbach's alpha , reliability (semiconductor) , cognition , ceiling effect , psychology , cog , dementia , scale (ratio) , clinical psychology , medicine , psychometrics , disease , computer science , psychiatry , artificial intelligence , alternative medicine , pathology , power (physics) , physics , quantum mechanics
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.