Operational Definition of Chronic Disability in the National Long-Term Care Survey

This application requests two years of funding to investigate the operational definition of chronic disability in the National Long-Term Care Survey (NLTCS). Published studies that use data or refer to results from the NLTCS vary in the amount of detail they provide on the definition of chronic disability employed by the survey. Most of these studies, however, oversimplify the NLTCS's operational definition of chronic disability by ignoring longitudinal features of the survey. This practice may lead not only to erroneous conclusions but also to misspecified policy implications. The NLTCS began in 1982 and now extends over six waves through 2004. It provides an important source of information on possible changes in disability over time among the elderly Americans. The NLTCS data on basic and instrumental activities of daily living have been used to generate some major findings such as showing a decline in chronic disability among the elderly Americans. However, complexity of the design, influenced by many decisions made in the early years of the survey, presents conceptual and analytic challenges for secondary users of the NLTCS data. In particular, the operational definition of chronic disability employed by the NLTCS is difficult to track down comprehensively. As a result, it often gets misinterpreted toward an oversimplification. Our preliminary study shows that the NLTCS by design measures some combination of chronic and short term disability as opposed to chronic disability as commonly stated in the literature. The primary aims of this project are to develop a comprehensive description of the operational definition of chronic disability used in the NLTCS and to investigate the impact of the design choices made by the NLTCS on the measurement of chronic disability. This project will illuminate the interplay between the basic definition of chronic disability, as a disability lasting more than 90 days, and the complex longitudinal design of the NLTCS. It will also investigate whether there are subgroups of the elderly population that are differentially affected by the NLTCS design choices as they relate to the measurement of chronic disability. Finally, it will explore whether additional data from the NLTCS can be used to obtain a valid chronic disability measure. Findings of this study will benefit secondary users of the NLTCS data and future designers of longitudinal surveys that aim to track chronic disability status of the elderly over time.