Afmc Primer on Population Health

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- Epidemiology focuses principally on variations between people that are systematic, meaning that identifiable groups of people (whether defined in terms of age, sex, social status, ethnic group or in some other way) experience different levels of health.

- Explanations for individual variations in health are generally formulated in terms of risk factors, which are characteristics of the person, of their behaviour or environment that affect their chances of contracting a given disease.

- Explanations for broad patterns of Chapter 2 Determinants of Health and Health Inequities 36 disease in whole groups of people refer to health ‘determinants’. Determinants often exert their effect via individual risk factors, and so may be viewed as the causes of the causes of disease.

- a key point is that there is a steady rise or gradient in longevity across income levels and this is called the ‘social gradient in health’. Similar health gradients occur across levels of education, occupation and residential area, all of which reflect socio-economic status.

- There are also consistent contrasts in health between certain racial or ethnic groups, as well as a clear contrast between the sexes the figure above shows Chapter 2 Determinants of Health and Health Inequities 37 that even poor women live longer on average than rich men

- As science has increasingly provided explanations for disease, the fraction of variation in health that is attributed to random or chance variations has steadily declined.

- Variations that are not random should in principle be correctable: if richer people can live longer, there is presumably no inherent reason why poorer people could not live equally as long

- Where this disadvantage is correctable or could have been avoided, it is termed an inequity, carrying the idea of unfairness and unacceptability. Inequities form a moral incentive for action. The most prominent sources of health inequity in Canada are socio-economic status and Aboriginal identity

2.2 basic concepts: causes, risk factors and determinants

- Effective disease management requires management of the immediate problem, then of the patient’s risk factors and lastly of the underlying determinants

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2.3 Risk Factors

- The triad model is useful for explaining cases of disease after they arise, but a central problem is that we are only just beginning to understand how to assess a person’s susceptibility ahead of time, so (at least until genetic analyses become much more sophisticated) we cannot accurately tell who will fall sick when exposed to a disease agent.

- We deal with this uncertainty probabilistically, and speak of ‘risk factors’ that increase the statistical probability that a person will fall sick

- Some risk factors have a direct and probabilistic effect on the likelihood of an adverse outcome, as with not wearing a seatbelt in the event of a motor vehicle collision.

- Others form part of a complex causal pattern like the effect of diet in relation to others on coronary disease

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- Health determinants refer to underlying characteristics of society that ultimately shape the health of individuals and communities. They can be thought of as the causes of the causes of ill health, or as ‘upstream factors

- Be careful: the term ‘determinant’ is not intended to imply inevitability or determinism; it comes from the Latin de termine, or “from the end” (i.e., the origin) of the causal chain.

- Determinants include non-specific factors (a recession, poverty, lack of education) and particular policies

- Underlying determinants determine which diseases are common in a population. This difference in prevalence will, of course, guide your differential diagnosis

- Details of the distinction between determinants and risk factors can be debated: many authors consider the population distribution of a risk factor as forming a determinant for individual cases.

- Finally, diseases themselves fall into a spectrum according to their pattern of causation, running from exclusively genetic conditions (such as cystic fibrosis) through conditions such as breast cancer, autism, or Type 2 diabetes that reflect both genetic and environmental influences, to others such as environmental mercury poisoning or post-traumatic stress disorder that are principally due to population-level determinants.

2.4 determinants of health

Early childhood development

- The life course perspective emphasizes that early experiences have a profound formative impact on an adult.

- Early nutrition, physical development and fitness are important, as is emotional development which, if positive, builds resiliency, and if negative, enhances vulnerability.

- Timing of exposures and experiences can be critical

- The recognition of critical periods in early child development has led to the popularity of infant stimulation programs, such as Head Start.

Income and social status

- A person’s social status is defined by a combination of their wealth, education, occupation and lifestyle, and (secondarily and to a varying extent) by other factors such as ethnicity, personality, and happenstance. Each of these, alone or in combination, can exert positive or negative influences on a person’s health

- The association between social status and health is now termed social inequalities in health (see Health inequality in Glossary) and is summarized in many sources.

- The most obvious of these influences is income − especially insufficient income − described either in relative or absolute terms. Absolute poverty refers to having inadequate resources to meet basic needs for shelter, nutritious food, clothing, and education.

- People living in poverty lack the resources and opportunities to make choices that promote good health.

- Being poor may also expose them to inferior physical environments that place them at risk for health problems.

Education and literacy

- Education is one of many characteristics that both contribute to, and also result from, social position.

- A person’s social position in childhood influences their access

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