The linkage of health status changes and disability.

Forecasting health and functional status changes in elderly populations is a difficult task because forecasting must describe the linkage of chronic morbidity, and its progression, with different levels and types of disability. In this paper we present a model which links morbidity and disability and, with the use of multiple survey and epidemiological data sources, provide estimates of the long-term reduction in chronic disability that would result from changing the prevalence of specific chronic diseases by the control of major risk factors. The results show that many of the diseases which are currently the principal target of primary prevention have more impact upon mortality, and overall life expectancy, than they do on the age at onset of chronic disability. Thus, in order to increase the average number of years that elderly persons can expect to live with less disability, or less severe forms of disability, new prevention strategies and techniques may have to be developed.