Chapter 1: EpidemiologicalApproaches to Population Health
- Epidemiology: the study of health and its determinants in specified populations with the often
unstated goal of improving health
- origin - John Snow - studied people who succumbed to cholera in London 150 years ago
- plotted an association between death and the sources of drinking water.
- He hypothesized the the disease was spread by contaminated water from evacuations of
infected people. Removed the pump handles, deaths subsequently declined.
- Epidemiologists mostly conducts studies and report results, action isnot usually
considered part of the discipline’s domain.
- Another health official at the time, William Farr, the registrar-general in London, recognized
that poverty was an important contributor to poor health.
Health as a Concept Differs on the Level Being Considered
- Examples provided. analogy of cells, organs, individual body
- There are population level health producing factors that have no individual level counterparts,
just as health advice for individuals has no cellular-level counterparts.
- If the population factors are right, then what individuals in that population do or don’t do for
their own health may not matter as much.
- They are health as a by product of the way the jurisdiction is organized, just as our cells are
healthy if we do what’s right for us as individuals.
- If this is the case, then we can produce the population factors in a particular society and obtain
health, or we may decide to organize society in such a way that the population will not be
- Canada as a nation has more of this population health framework than the US for example,
although citizens in Canada as elsewhere tend to be unaware of how population level factors
impact their health.
- The task of epidemiologists and others working for health is to make them aware.
- Associations of cells as organs and the factors that produce disease in these organs are the
primary concern of most epidemiologists.
- They study the incidence and prevalence of diseases such as heart disease, lung cancer, and
Alzheimer’s and attempt to identify the precipitating factors that lead to these afflictions.
Population Health Epidemiology
- How John Snow worked - door to door and collected information on water sources and death
- Such observational data forms the backbone of epidemiological investigations
- For a disease focused approach, one needs to know whether or not someone has the disease,
and then obtain a variety of supplemental information to discern what is going on.
- lung cancer example - pg. 17k
- Social epidemiology: reflects the population or societal level of analysis - Epidemiologists have graduate training (usually in public health schools) and work in public
health departments at various levels.
- Acommon approach in modern epidemiology limits the validity of discoveries. Unless you
look at people who are similar in important respects, you won’t find what you are looking for.
They must have similar incomes, or education, or wealth, or status in society.
- In the jargon of epidemiology, you have to control for socio-economic status in a study, or you
won’t find an effect.
- Controlling means that you factor out the importance of that variable in the analysis. Then you
cannot ask questions about that variable.]
- Hence, socio-economic status must be very important in producing health. If it wasn’t, then one
wouldn’t need to control for socio-economic status in studying other factors.
- How you frame the question profoundly impacts what answer you get.
- Defining a disease can be very political. Eg. Homosexuality. Fibromyalgia and chronic fatigue
- Figure 1.1 Time line of epidemiology - pg. 18
Learning from Health Data on Populations
- World Health Organization (WHO) Definition of Health:
- Health is a state of complete physical, mental, and social well being and not
merely the absence of disease or infirmity.
- Self assessed Health (SAH)
- Asking individuals how healthy they consider themselves on a scale from very
unhealthy to very healthy.
- For a population, consider the average length of life (life expectancy), or the infant mortality
rate (IMR). Out of 1000 infants born, the IMR measures how many die in their first year of life.
These can give us numbers allowing us to ask what may maximize health.
- IMR is a more sensitive measure than others since early life is so critical to adult health
- Examples pg. 20-22
- To summarize the findings, relative poverty is bad for your health. That is for almost any
condition, being lower in the socio-economic ladder is bad for you.
- Poverty has an effect that is not just related to personal behvaiours engaged in by poorer or
- Many Health Canada Documents: Relative deprivation or relative poverty has been found to be
an important aspect of inequality that impacts health.
- The best study looking at the impact of health care services in advancing health was done in
Winnipeg, Manitoba by looking at mortality outcomes related to cuts in health care services.
- To conclude, a univeral health care system is definitely the right policy tool for
delivering care to those in need, and for this it must be respected and supported.
However, investments in the health care system should never be confused with, or sold
as, policies whose primary intent is to improve population health or to reduce
inequalities in health. Claims to that effect are misleading at best, dangerous and highly
wasteful at worst. - In developed nations such as Canada then, medical care is not as important in producing health
in a population as are these other factors.
- For the nonspecialist and specialist doctors and the general public, this is the most difficult
concept to grasp. From “the Oxford Textbook of Public Health” “The impact of personal
medical services on the health and survival of individuals seems readily apparent. With
modern investigations and treatments, patients are now regularly saved and make very good
recoveries from infections, injuries, and a variety of other conditions that were almost
uniformly fatal even a few years ago. Suprisingly, it is more diffiuclt to demonstrate
conclusively the impact of these medical advances on the health of a whole community.
Inequality in Society is Bad for Your (Our) Health
- Smaller economic gap = better health generally
- The most commonly used measure of inequality is that of income differe.ces. Flawed way to
measure - eg. th