This project will develop a Health-Related Quality (HRQ) staging system to distinguish among subgroups of people in the community who have carious health conditions and types of disabilities. Stages will be defined based on a global estimate of Health-Related Quality of Life (HRQL), which is expressed through a composite variable combining illness behaviors (objective component) with perceived health status (subjective component). The composite measure acknowledges relationships between health states and HRQL that can differentially affect behaviors or perceptions, depending on cultural and other environmental contexts as well as individual motivational differences. Through the process of staging, HRQL will be linked within health condition categories to specific limitation profiles across physical and emotion function domains Data will include information on 145,007 respondents from the 1994 and 1995 National Health Interview Survey of Disability, Phase I. This study will incorporate a cross-sectional multistage sampling design with the use of weighted data to allow unbiased parameter estimates. Statistical testing and the construction of confidence intervals will take into account this multi- stage sampling design. The staging system will be developed through a classification tree approach and tested through split-sample validation. Input from a panel of expert clinicians will help define health condition categories from underlying diagnoses and interpret the clinical significance of various disability profiles. Through a series of logistic regression models, the derived staging system will then be used to test specific hypothesis about the impact of personal traits and the physical and social environments on HRQL. HRQ staging has applications for planning the health management of large outpatient populations, clinical trials, and health care policy. Results should provide insight into the factors that determine HRQL and will be used to evaluate a theoretical model intended to clarify and provide and unified conceptual basis for approximating quality of life. In this model, quality of life is a latent state resulting from interactions among the body, the mind, and the physical and social environments. It relates to discordance between perceived and desired states of being.
