ADCS Prevention Instrument Project: quality of life assessment (QOL)

Information about quality of life (QOL) is valuable in evaluating pharmaceutical agents but it is not adequately assessed in many dementia drug trials. In prevention trials, following participants to conversion to AD requires QOL scales appropriate for both normal and cognitively impaired individuals. Our objective was to evaluate the utility of several scales for subject or informant QOL assessment: Quality of Life-AD; Quality of Life Activity Inventory; SF-36; SF-12 (a shortened version of the SF-36); and Satisfaction with Life Scale. Measurements were collected from 644 subject-study partner pairs, half of whom completed the instruments at the clinic and half at home. Three-month test-retest data were collected. Scales administered at home or in clinic did not differ significantly. Subject self-ratings showed a wide range for all scales. Test-retest intraclass coefficients ranged from 0.67 to 0.77. Moderately high interscale associations suggest that the scales are measuring common aspects of QOL but are not equivalent. Furthermore, they differed with respect to associations with demographic variables and QOL determinants. We conclude that the QOL scores at baseline show sufficient range and reliability to suggest they will have utility in tracking QOL through conversion to dementia.