Definitions of Health
Health is elusive to define and ways of thinking about it have evolved over the years. Three leading approaches include the "medical model", the "holistic model", and the "wellness model":
(1) The medical model was dominant in North America throughout the 20th century.
· In its most extreme form, the “medical model” views the body as a machine, to be fixed when broken.
· It emphasizes treating specific physical diseases, does not accommodate mental or social problems well and, being concerned with resolving health problems, de-emphasizes prevention.
· This has led logically to measuring health by its absence, e.g., by disease or death rates. Therefore health is defined as the absence of disease and the presence of high levels of function. A (rather wordy) example would be: "A state characterized by anatomic, physiologic and psychologic integrity; ability to perform personally valued family, work and community roles; ability to deal with physical, biologic, psychologic and social stress..." (Stokes J. J Community Health 1982;8:33-41)
· Applied to population health, the medical model might define a healthy population as one in which its members were all healthy. Alternatively, the mechanical metaphor could be applied to the society itself: a healthy society is one in which the various systems (economic, legal, governmental, etc.) function smoothly.
(2) The holistic model of health is exemplified by the 1947 WHO definition, "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity".
· This model broadened the medical model perspective, and also introduced the idea of positive health (although the WHO did not originally use that term).
· The WHO definition was long considered unmeasurable; the terms were vague. This was less because no-one could invent ways to measure "well-being," (indeed, psychologists had done so) but more because doing so required subjective assessments that contrasted sharply with the objective indicators favored by the medical model.
· Applied to a population, the holistic model would again either sum appropriate individual indicators, or would record measures of the well-being of the population as a whole.
(3) The wellness model was developed through the WHO health promotion initiative.
· In 1984, a WHO discussion document proposed moving away from viewing health as a state, toward a dynamic model that presented it as a process or a force.
· This was amplified in the 1986 Ottawa Charter for Health Promotion. The definition held that health is "The extent to which an individual or group is able to realize aspirations and satisfy needs, and to change or cope with the environment. Health is a resource for everyday life, not the objective of living; it is a positive concept, emphasizing social and personal resources, as well as physical capacities." (Health promotion: a discussion document. Copenhagen, WHO, 1984.)
· Related definitions include some that view health in terms of resiliency (e.g., "the capability of individuals, families, groups and communities to cope successfully in the face of significant adversity or risk." (Vingilis & Sarkella, Social Indicators Research 1997;40:159)
· Applied to population health, the definition might include elements such as the success with which the population adapts to change such as shifting economic realities or natural disasters.
· An ecological definition is: "A state in which humans and other living creatures with which they interact can coexist indefinitely." (Last JM. Dictionary of epidemiology. IEA, 1995:73)
Each of these models has something to contribute, though none seems ideal.
· The advantage of the medical model is that disease represents a crucial issue facing society, and disease states are readily diagnosed and counted. But this approach is narrow, and in extreme form implies that people with disabilities are "unhealthy," and that health is only about physical disease and mortality.
· A further potential limitation to the medical model is its omission of a time dimension. Should we consider as equally healthy two people in equal functional status, one of whom is carrying a fatal gene that will lead to early death? Further, if prognosis is not included, there is no virtue in prevention.
· The holistic and wellness models have the advantage of allowing for discrimination of people at the higher end of functioning; they focus on mental as well as physical health, and on broader issues of active participation in life.
· They also allow for more subtle discrimination of people who succeed in living productive lives despite a physical impairment: blind people or amputees may still be able to satisfy aspirations, be productive, happy and so be viewed as healthy.
· The disadvantage is that these conceptions run the risk of excessive breadth, of incorporating all of life. Thus, they do not distinguish clearly between the state of being healthy and the consequences of being healthy; nor do they distinguish between health and the determinants of health. For example, social health may be viewed as a determinant more than a marker of health status; it is subject to influence by very different factors.
· A further challenge is that by espousing a dynamic model of health (e.g., the capacity to rally from insults), healthiness predicts itself. Hence, we must also move from a strictly linear model of cause and effect toward a systems model in which health is a force, both input and output, and not merely an output of a linear process.
· Many of these ideas shown in these evolving models of health have been further developed in discussions of alternative medicine.
Impairment: "any loss or abnormality of psychological, physiological, or anatomical structure or function" (WHO International classification of impairments, disabilities and handicaps. Geneva, 1980)
Disability: "any restriction or lack (resulting from an impairment) of ability to perform an activity in the manner or within the range considered normal for a human being" (Idem)
Handicap: "a disadvantage for a given individual, resulting from an impairment or a disability, that limits or prevents the fulfillment of a role that is normal (depending on age, sex, and social and cultural factors) for that individual" (Idem)
Frailty: "a grouping of problems and losses of capability which make the individual more vulnerable to environmental challenge"
Link to further discussion of definitions of disability
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