HSCI 130 Week 8 Lecture

Observational studies

researcher does not intervene in any way

• Measurement of occurrence of disease or health outcome

• Comparing patterns of exposure and disease outcomes

• Identifying risk factors associated with health/disease

Both descriptive and analytical can fit here!

Experimental studies

investigator tries to change something and measure the effect on disease outcome

• clinical trials, preventive trials

Descriptive Studies

Research that describes the occurrence of disease and/or exposure.

e.g.

• Remember: PERSON PLACE TIME

• Ask: WHO? WHAT? WHEN? WHERE?

Case reports / case series:

detailed descriptions usually by a doctor or group of doctors identifying diseases that are unusual/interesting; may be related to unusual exposure

Routine data: mortality, life expectancy

Prevalence surveys

Analytic Studies

Primary purpose is to evaluate the ASSOCIATION between an EXPOSURE or CHARACTERISTIC and the development of a particular disease.

• WHY?

• HOW STRONG?

What’s an Exposure?

• Infectious agents

• Behaviours

• Intrinsic characteristics of individuals

• Social or environmental factors

D)

Ecological Studies

Compares the prevalence of exposures and disease occurrence in populations

Warning:

observations collected/displayed at the group level may not apply at the individual level

Cross-Sectional studies

Limitation: temporal relationship between exposure and disease

E.g. stress and sleep deprivation

Advantages: inexpensive, can estimate prevalence, can estimate association between variables, can study many diseases and outcomes at the same time

Disadvantages: temporality

Case Control Study

Choose individuals with disease or outcome of interest and a comparison group without the disease (controls)

Retrospective

Both groups from same environment

Find if cases are more exposed than controls 

Good for rare diseases

Not good for rare exposures

Cannot calculate incidence of diseases

Has inaccuracies

Prospective Cohort Studies

Start with exposures and find cases 

Follow people over time to see what happens

Compare rates of occurrence of disease in people with or without particular exposure

Prospective 

Advantages:

Better for rare exposures, more confident in temporality, 

Disadvantages:

Bad for diseases with long latency period, not well suited to rare disease, long follow up time, lost to follow up.

Rationale and Research Question: example of cohort study

Cocoa consumption may improve CVD outcomes

Research Question: What about habitual consumption in a group of the population at high risk for heart disease?

Randomized Controlled Trial

problems:

• Ethics issue

• Funding

Determinants of Health

Personal

Structural

Personal Determinants of Health

Personal determinants – individual level

• Lay health beliefs

Self-health management

• Self-care capacity

• Coping skills

Biology and genetic endowment

Health protective behaviour

• Personal health practices

• Healthy lifestyles

Structural Determinants of Health

Social environment

• Socioeconomic status AKA Socio-economic position

• Social status

• Income and income distribution

• Education

• Employment & working conditions

• Gender, ethnicity/race, age, culture

• Social support networks

Physical environment

Health-care & social services

• Disease prevention

• Health promotion

• Healthy child development

1848

World-wide cholera epidemic begins

Uprisings in many countries

Start of Second Sikh war against British in India

Revolution in France, which creates a public health advisory committee

Karl Marx and Friedrich Engels publish The Communist Manifesto

Early Evidence: The Condition of the Working Class in England (1844)

Method:

• Examined observed differences in mortality rates in suburbs of Manchester

Findings:

• observed death rates correlated with quality of housing and quality of streets

“observed death rates correlated with quality of housing and quality of streets—and are worked every day to the point of complete exhaustion of their mental and physical energies.”

Early Evidence: Rudolf Virchow’s Study

Method:

• Sent to investigate an epidemic of typhus in Upper Silesia

Findings:

Conclusion/Virchow’s recommendation:

Preserving health and preventing disease requires “full and unlimited democracy“ and radical measures rather than "mere palliatives”

Public Health Agency of Canada:

12 Key Determinants

The Social Gradient In Health

• a graded association between the indicator of socioeconomic status and population health

• where you stand in the social hierarchy is intimately related to your chances of getting ill and your length of life

Socio-economic position(SEP)

Social and economic factors that influence what position individuals and groups hold in the social structure of a society

Individual Level Measures:

• Occupation

• Income

• Income in relation to poverty level

• Education

• Wealth

Area Based Measures:

• Geographic area

How Does SEP Impact Health?

Political, cultural and institutional factors influence HOW socio-economic conditions influence health outcomes

Income & Children’s Health

Uses data from the NPHS and NLSCY (National Longitudinal Study on Children and Youth)

Income associated with:

• Low birth weight

• Injury related mortality (fire and homicide deaths)

• Developmental problems (hyperactivity, psychosocial problems, delinquent behavior, delayed vocabulary)

Neighbourhood Income and Obesity

Explanations of Social Gradient

1. Materialist Explanations

2. Cultural Behavioural Explanations

3. Psychosocial Explanations

Materialist Explanations

Differential exposure hypothesis: greater exposure to psychosocial stressors from financial problems, neighbourhood issues and social isolation

• People exposed to positive and negative exposures over the life course and outcomes in adulthood are indicators of advantages and disadvantages…

Aspects of the social structure (e.g. differences in SES) are powerful determinants of health

Influenced by the political economy perspective of the conflict paradigm

Neo-materialist Explanations

• Health is affected not only by differential access to social and economic resource, but also by the level of funding invested in social infrastructure

• e.g., public infrastructure quality

Cultural Behavioural Explanations

How we learn how to behave in society

Lower-SES individuals are less healthy as a result of engaging in health related behaviours such as smoking or poor eating habits (to cope)

Differential vulnerability hypothesis: all have stressors; position in social gradient can help mitigate or make these worse

Assumption:

• These individuals do not cope very well with environmental stressors and therefore, experience worse health

Psychosocial Explanations

People’s interpretation of their standing in the social hierarchy matters

Sense of relative deprivation can generate feelings of low self-esteem, shame, envy

Strive and fail → negative health consequences

Social comparison;

perception of hierarchy leads to stress comparisons lead to shame, envy, other mental health outcomes and/or other negative behaviours