Detecting treatment effects with combinations of the ADAS-cog items in patients with mild and moderate Alzheimer's disease

✍ Scribed by Ralf Ihl; Steven Ferris; Philippe Robert; Bengt Winblad; Serge Gauthier; Frank Tennigkeit

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 147 KB
• Volume: 27
• Category: Article
• ISSN: 0885-6230
• DOI: 10.1002/gps.2679

✦ Synopsis

Abstract

Objective

When complex cognitive functions are measured with multi‐item scales like the Alzheimer's Disease Assessment Scale – cognitive subscale (ADAS‐cog), it seems valuable information can be lost due to combination of the ADAS‐cog items results into a total score. We hypothesized, that an analysis of the results of different ADAS‐cog item combinations may reveal drug treatment effects in distinct cognitive domains and/or enhance the sensitivity to detect such treatment effects. Here, we present a novel approach called ‘subsetting analysis’ for assessment of drug treatment effects with multi‐item scales, like the ADAS‐cog.

Methods

The subsetting approach is a mathematical algorithm designed to select and group scale items in a subset detecting drug treatment effects in a particular study population. The approach was applied in a post‐hoc analysis of ADAS‐cog results from two randomized, placebo‐controlled and double‐blind clinical trials with memantine in mild to moderate Alzheimer's disease (AD). The subsetting analysis of the ADAS‐cog combined database aimed at selecting the scale items showing no worsening at study end compared to baseline due to memantine treatment in mild AD (Mini‐Mental State Examination (MMSE >19)) patients.

Results

Two ADAS‐cog subsets were finally revealed by the analysis: a subset of five ADAS‐cog items, identified as most sensitive to memantine effects in mild AD patients, and a subset of six ADAS‐cog items shown to detect significant memantine effects in moderate AD patients.

Conclusion

The subsetting approach of analyzing ADAS‐cog data is a powerful alternative for gaining information about drug effects on cognitive performance in mild and moderate AD patients. Copyright © 2011 John Wiley & Sons, Ltd.