Lecture 2 & 3 Intro to Epidemiology Flashcards
Epidemiology
Public health discipline basic science which studies
-Distribution
-Determinants
in specified populations
Figuring out what causes disease and who gets it
Distribution of Disease
Frequencies and Patterns of disease
Disease Frequency
Part of Distribution of Disease
Not only counts but also counts in relation to size of population
-Comparisons between populations possible
Disease Patterns
Part of distribution of disease Encompasses: -Person -Place -Time
Descriptive Epidemiology
Who
When
Where
The 3 W’s
Determinants of Disease
AKA Risk Factors or Associations
Can be positive (associated with reduction, prevention) or negative (increase, promotion)
Ex negative risk factor
smoking and lung cancer
Ex positive risk factor
breast cancer and breastfeeding
Analytic Epidemiology
Why and How
Determinants of Disease
Objectives of Epidemiology
Study natural course of disease
Determine the extent of disease
Identify patterns and trends in disease
Identify the causes of disease
Evaluate the effectiveness of measures that protect and treat disease
Assist in developing public health policy
IN POPULATIONS
Father of Epidemiology
John Snow
John Snow
Father of Epidemiology
Observed people dying in community, wanted to know why, finally figured out it was water supply, took pump off and disease decreased.
Last pandemic
2009 H1N1 (Influenza A)
Last pandemic before H1H1
1918
What does basic science study?
Cells, tissues, animals
What does clinical study?
Sick patients
What does public health study?
Populations or communities
Basic science research goals
Understanding disease mechanism and effects of substances
Clinical research goals
Improving diagnosis and treatment of disease
Public health research goals
Prevention of disease and promotion of health in the population
Basic science examples
Pharmacology, Microbiology, Biochemistry
Clinical science examples
Internal Medicine, Health Policy & Management
Dr source of data
History and physical exams
Epidemiologist source of data
Surveillance and descriptive epidemiology
Dr assessment
Differential diagnosis
Epi assessment
Inference
Dr Hypothesis testing
Diagnostic studies
Epi Hypothesis testing
Analytical Epidemiology
Dr Action
Treatment
Epi Action
Community Intervention
Epidemiological Assumptions
- Disease occurrence is NOT random
- Systematic investigation of different populations can identify associations, causal and preventive factors
- Making comparisons is the cornerstone of systematic epi investigations.
What is the cornerstone of systematic epidemiological investigations?
Making comparisions
6 core functions of epidemiology
- Public Health surveillance
- Field investigation
- Analytic studies
- Evaluation
- Linkages
- Policy development
Public health surveillance
Core Function of epi
count, track and record
To portray the ongoing patterns of desease occurrence so that investigation, control and prevention measures can be applied
Field investigation
Core Function of epi
ask questions and look for what they have in common
To determine source or vehicle of disease or to simply learn more about the natural history, clinical spectrum, descriptive epidemiology and risk factors of a disease
Analytic studies
Core function of epi
start setting up comparison groups, do assumptions hold true?
To advance the information (hypotheses) generated by descriptive epidemiology techniques
**Hallmark is use of comparison group
Evaluation
Core Function of epi
Figure out what you are looking at data wise
Evaluate findings
To determine, as systematically and objectively as possible, the relevance, effectiveness, efficiency and impact of activities with respect to established goals
Linkages
Core Function of epi
Talking. When you figure out what cause is, do something!
Policy Development
Core Function of epi If public health related event that needs policy to change, start it! To collaborate (link) with other professionals
Examples of policy development by epi
Helmet laws, smoking bans
Public health surveillance examples
Reportable diseases registry (pertussis, meningitis)
Field investigation examples
Ground beef as source of o157:H7
Eggs as source of salmonella
*initial investigation of “SARS” before it was named and known
Hallmark of an analytic study is
the use of a comparison group
Key skills for Analytic studies
Design, conduct, analysis, interpretation and communication of research study processes and data
Linkage examples
Laboratory specialists Sanitarians Physicians Federal, state and regional governments Communities
Definition of Epidemiology ends with…
“…and the application of this study to the control of health problems.”
Core function of epi, policy development
The Epidemiological Approach
describing groups and events by:
- Counting
- Dividing
- Comparing
Counting
Counting cases/health events and describing them in terms of person, place and time
-Case and study population definitions a key function
Dividing
Dividing the # of cases by an appropriate denominator to calculate rates, ratios and proportions
Comparing
Comparing rates over time for different groups of people
2 Categories of Studies
- Observational (descriptive, analytical)
2. Experimental (interventional aka clinical)
Observational Studies
Descriptive
Analytical
Experimental Studies
Interventional aka Clinical
Types of Analytical Studies
Case-Control
Cohort
Experimental - Pre Clinical - Phase 1 - 2 - 3 - 4
Population
All individuals making up a common group; from which a sample (smaller set) can be obtained, if desired.
**Don’t confuse with ‘study population’, which is the final group of individuals selected for study
Sample
A subset or portion of the full, complete population (representatives)
-useful when studying the complete population is not feasible
Ways to acquire a sample
Random number generator (computer)
Pre-defined sample (every 3rd patient, everyone admitted on weekends)
Convenience sample
Inferential Statistics
Inferences (conclusions) made about random data relative to a sample
Generalizability
Inferential statistics transposed from the sample to the full population
Epidemic
Occurrence of disease clearly in excess of normal expectancy
- Community/Period clearly defined
- Goal is to capture disease as early as possible
Endemic
The constant presence of a disease within a given area or population in excess of normal levels in other areas
Ex. Malaria in UK
Outbreak
aka Upsurge/cluster
An epidemic limited to a localized increase in the occurrence of disease
Pandemic
An epidemic occurring over a very wide area involving a large number of people
*Many times multi-region or multi-national
Primary Prevention
Preventing or halting a disease before it occurs or becomes established
Example of Primary Prevention
Low dose aspirin in prevention of cardiovascular disease in women
Secondary Prevention
Interrupts the disease process before it becomes symptomatic or prevents it from progressing or recurring
