mance, the degree of work disability could be reduced by improving the individual’s capacity to accomplish functional activities (a very traditional view of rehabilitation) or by manipulating the physical or social environment in which work occurs.
The fundamental conceptual issue of concern is that a health-related restriction in work participation may not be solely or even primarily related to the health condition itself or its severity. In other words, although the presence of a health condition is a prerequisite, “work disability” may be caused by factors external to the health condition’s impact on the structure and functioning of a person’s body or the person’s accomplishment of a range of activities.
The earliest disablement models represented by Nagi (1965) and the ICIDH-1 formulation (WHO, 1980) presented the disablement process as more or less a simple linear progression of response to illness or consequence of disease. One consequence of this traditional view is that disabling conditions have been viewed as static entities (Marge, 1988). This traditional, early view of disablement failed to recognize that disablement is more often a dynamic process that can fluctuate in breadth and severity across the life course. It is anything but static or unidirectional.
More recent disablement formulations or elaborations of earlier models have explicitly acknowledged that the disablement process is far more complex (IOM, 1991, 1997b; Verbrugge and Jette, 1994; Badley, 1995; WHO, 1997, 2001; Fougeyrollas, 1998). These more recent studies note that a given disablement process may lead to further downward spiraling consequences. IOM (1991) uses the term secondary conditions to describe any type of secondary consequence of a primary disabling condition. IOM (1991) also included quality of life in the conceptual model, although little attention was given to how to define this concept or make it operational for persons with disabilities. Patrick (1997), in rethinking preventive interventions for people with disabilities, focused on opportunity as the intersection between the total environment and the disabling process and defined opportunity as the four goals of the ADA, including economic self-sufficiency and full participation, which are highly related to work. Quality of life is viewed as people’s perceptions of their position in life in the context of culture and personal goals and expectations. Quality of life is the final outcome and is influenced by all aspects of the total environment, experience with health care, the disabling process, and level of opportunity.