Intro Flashcards
What is epidemiology?
A quantitative science that looks at health from a population level to address public health goals and to understand cause and effect relationships between certain exposures and disease outcomes.
Epidemiology studies…
the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.
Objectives of Epidemiology
- To study the natural history of disease
- To identify causes of disease
- To determine the extent of disease
- To evaluate measures that prevent and treat disease
Study Design: Descriptive
Describes only – does not examine relationships • Surveillance data • Case reports • Surveys • Case series
Study Design: Analytic
Examines relationships / Test hypotheses
Experimental: Investigator assigns exposure Observational: No intervention – investigator observes
• Ecologic
• Cohort
• Cross Sectional
• Case Control
Possible Exposure/Disease relationships: Limited evidence of a relationship
Unworthy of study
Possible Exposure/Disease relationships: Good evidence of a relationship(more research warranted)
Worthy of Study
Possible Exposure/Disease relationships: Strong evidence of a relationship (accepted as causal)
Basis of public policy
Hills Causal Criteria
Temporal Relationship Strength Dose-Response Relationship Consistency Biological Plausibility Coherence Experiment Analogy Specificity
Temporal Relationship
Exposure comes before the disease
Strength
Magnitude of observed effect
ex. smoking increases risk of lung cancer 10X
Dose-Response Relationship
Not always observable
The more you smoke, the stronger the association
Consistency
Replication of findings / Is it being observed over and over again?
Biological Plausibility
Do we understand the mechanism? Does it seem possible that inhaling smoke into your lungs might cause lung cancer?
Experiment
Can we assign study participants to one exposure or another and then follow them for the outcome?
Analogy
Supported by similar research
If we see that smoking causes lung cancer, what about another exposure such as asbestos?
Modified Determinism
Modified Determinism is a model that explores component, necessary and sufficient causes. It considers sets of exposures or characteristics that are sufficient to cause disease.
Necessary Cause
found in all cases
Component Cause
needed in some cases
Sufficient Cause
the set of necessary and contributing causes that make disease inevitable
Causal
The exposure is part of the causal pie leading to disease
Chance
There is no association even though one was observed
Reverse Causation
The disease causes the exposure
Bias
Some aspect of the execution of our study or analytic approach results in us getting the wrong answer
Surveillance
What is the problem?
Process begins when a health problem is recognized
For example, we might observe that there is suddenly a large increase in the number of case reports for a specific disease.
Risk Factor Identification
What risk factors are associated with a given outcome?
ex. People who inject drugs are 22 times more likely to acquire HIV compared to those who don’t inject drugs
Intervention Evaluation
What works?
ex. Surgeon General issues a statement that eating fresh fruits and vegetables and exercising regularly helps prevent heart disease
Implementation
How do you do it?
