Review of outcome measurement instruments in Alzheimer's disease drug trials: psychometric properties of functional and quality of life scales.

The psychometric properties of functional and quality of life outcome measures that were used for the purpose of showing changes in antidementia drug trials for Alzheimer's disease are described and critiqued. The seven functional scales reviewed for reliability, validity, and responsiveness to change included the Geriatric Evaluation by Relative's Rating Instrument, the Physical Self-Maintenance Scale, the Instrumental Activities of Daily Living, the Blessed Dementia Scale, Part 1 and its revised version, the Interview for Deterioration in Daily Living with Dementia, the Unified Activities of Daily Living, and the Dependence Scale. The Progressive Deterioration Scale and Quality of Life Assessment were classified as quality of life scales. The majority of the scales were found to exhibit serious limitations, such as incomplete reliability and validity assessment for the intended uses. The most pervasive problem was a lack of data on responsiveness to change. It is recommended that further research be conducted to develop new tools or enhance existing measures for the assessment of both quality of life and functional ability.