Psychometric Comparison of Standard and Computerized Administration of the Alzheimers Disease Assessment Scale – Cognitive Subscale (ADASCog)

Abstract

The Alzheimer’s Disease Assessment Scale – Cognitive Subscale (ADAS-Cog) has become the de facto gold standard for assessing the efficacy of anti-dementia treatments. However, manual administration of the ADAS-Cog is subject to procedural inconsistencies, including scoring and transcription errors, which can introduce unwanted variance and compromise data quality within and across sites and trials. To address such concerns, a computerized version was developed that integrates, rather than replaces, the examiner, standardizes administration, and uses electronic data capture at the point of patient contact. The examiner can control administration and pacing, pause or repeat digitized instructions, score verbal report and overt behavioral performance, and freely interact with the subject. To conduct psychometric comparisons of traditional, paper-based administration of the standard ADAS-Cog (sADAS) with examiner- assisted administration of the computerized ADAS-Cog (cADAS). Eighty-eight patients (39M; 49F) with mild to moderate Alzheimer’s disease were tested on three occasions with each version over a period of one year with one month between paired visits. Intraclass Correlation Coefficients (ICC) comparisons between sADAS and cADAS were significant for total score (ICC=0.96) and all subscores (ICCs ranged 0.78-0.93), with no significant differences on paired t-tests. The mean ICCs across cADAS scores for test-retest reliability for short-term (mean ICC=0.96) and long-term (mean ICC=0.91) comparisons were significantly higher than across sADAS scores (mean ICCs were 0.87 and 0.84, respectively). These results indicate that examiner-assisted, computerized administration is equivalent to traditional, paper-based administration, and shows significantly greater test-retest reliability.