Descriptive Epidemiology (Epidemiology) Flashcards
Define descriptive epidemiology
Variations in health and disease in relation to PLACE, TIME, and PERSON
Importance of descriptive epidemiology
- Determine biological norm
- Determine cause of disease
- Separate environmental from genetic causes
- Establish need for treatment and prevention
- Helps in making diagnoses from a particular clinical presentation
3 ways we can test variation between places?
Geographical study- simple mapping of disease e.g. John Snow’s mapping of disease cases to determine source of Cholera. BEST FOR INFECTIOUS CAUSES
Migration study - comparing how risk of disease changes when people migrate BEST FOR GENETIC/EARLY ENVIRONMENTAL CAUSE VS ADULT ENVIRONMENTAL CAUSE
Show that in people migrating from low BP origin to higher (adopted) population, BP changes to match adopted population. Therefore Adult environmental influence on BP
Ecological study - study by population rather than individual case. e.g. England, Wales, one population is 1 unit, so asthma cases in Wales as compared to England CAN BE USED FOR NON INFECTIOUS CAUSES
Characteristics of populations in which blood pressure does not rise with age
Rural communities
Hunter gatherer, diet low in fat/salt/alcohol
Low mean BMI
High physical activity
Pitfalls migration studies
Selection bias - do those who migrate have a characteristic that those who don’t do not
Diagnostic criteria may be different between countries
Methods of measurement may differ
Ascertainment bias- access to healthcare may differ
Stress of migration - could this contribute to observed disease patterns
Pitfalls of ecological studies
Associations found may not be applicable on an individual level as analyses are based on population groups. If it does not then the association is not likely to be causal - ECOLOGICAL FALLACY
Population groups usually differ in multiple ways so ecological associations can be compounded by other factors related to the exposure disease.
