Utility of the Dependence Scale in dementia: validity, meaningfulness, and health economic considerations

The concept of dependence has been proposed as a unified representation of disease severity to quantify and stage disease progression in a manner more informative to patients, caregivers, and healthcare providers. This paper provides a review of the Dependence Scale (DS) as a quantitative measure of Alzheimer's disease severity, its properties as an outcome measure, a metric of disease progression, and a correlate of medical costs. The literature supports the notion that the DS is related to, but distinct from, key severity measures, including cognition, function, and behavior, and captures the full spectrum of patient needs. It also presents as a useful measure for assessing disease progression. Results underscore the importance of the DS as a unique endpoint in Alzheimer's disease clinical trials, providing important information about the impact of therapeutic interventions. The DS also is a useful measure for economic evaluation of novel interventions aimed at delaying progression.