Definitions: Health, Disability, Quality of Life These are abstract concepts, so there is no single and permanent way to define, and hence to measure, them. The definitions are open to discussion and so have evolved over time. Here is an overview of how our thinking has changed.

Definitions of ‘health’ have broadened over time Medical model ( ≈ anatomical integrity) Holistic model (adds mental & social function) Wellness or ecological models (functioning within an environment) Hold this thought: These can apply to health of individuals and to the health of populations

1. Medical Definitions: two examples “Health is the absence of disease” Health is… "A state characterized by anatomic, physiologic and psychological integrity; ability to perform personally valued family, work and community roles; ability to deal with physical, biologic, psychological and social stress..." (Stokes J. J Community Health 1982;8:33-41)

Medical Conception of Disease Diagnosis Therapy begun ‘Outcome’ (alive, dead, cured, etc) Symptoms appear Biological onset of disease Clinical Phase Preclinical Phase

2. Holistic Definitions “A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity" (WHO, 1948)

3a. Wellness Definitions "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)

3b. Ecological Definition “A sustainable state in which humans and other living creatures with which they interact can coexist indefinitely, in equilibrium.” (Last J. Dictionary of epidemiology. Oxford, N.Y., 2001)

Clarifying Disability WHO, 1976: Impairment Disability Handicap (International Classification of Impairments, Disability, & Handicap: ICIDH) WHO, 2001: Impairment Activity Participation (International Classification of Functioning: ICF)

Quality of Life In the grand debate between the narrow model of medicine (to treat an illness) and the broad (to restore function), what is the overall goal? Some answered in terms of enhancing well-being, but this has a connotation of material & economic wealth, which fall outside the ambit of medicine. Another issue was that heroic medical interventions sometimes caused adverse effects, so there was a need for an overall criterion that balanced the harms and benefits of therapy. In the 1980s, medicine seized on the term ‘quality of life’ (which had been lying around the social sciences for years). It is generally defined in terms of being able to function in desired social roles, even if you have a health problem, and relies on the subjective perception of the patient.

Health at the Population Level The previous ideas referred to individuals: your main future work, but we can also think of the health of populations. This is either merely the average of the health of individuals (e.g. how many had a heart attack last year?). This is “health in the population”, Or it could refer to the health of the population as a whole: is it a caring society? Are people’s rights respected? Does the system function well: do things get fixed on time? This is “health of the population” and it is relevant to the physician’s role as health advocate.