T1 L12: Prevalence and cross-sectional studies Flashcards
What is Epidemiology?
Basic science of the distribution and determinants of the frequency of disease/health outcomes in specific populations
What is prevalence?
The frequency of cases of a given disease in a population
What is point prevalence?
Prevalence at a point of time
Eg. Woman experience infertility right now
What is period prevalence?
Prevalence over a specific period of time
Eg. Woman who have experienced infertility in the last 12 months
What is Lifetime prevalence?
Prevalence of the disease/condition ever in an individuals lifetime
Eg. Woman who have experienced infertility ever in their lifetime
What are some strengths of cross-sectional and ecological studies?
- Measure prevalence
- Compare prevalence in exposed and non-exposed risk factors
- Quick and inexpensive
- Can be used to inform hypothesis
What is a cross-sectional study?
A type of observational study that analyses data from a population, or a representative subset, at a specific point in time
What is an ecological study?
Used to understand the relationship between outcome and exposure at a population level
What are some weaknesses of cross-sectional and ecological studies?
- Not suitable for rare diseases
- Not suitable for diseases of short duration
- Cannot measure rate of new cases arising
- Vulnerable to bias
What is a confounding variable?
A variable that influences both the dependent variable and independent variable
Eg. how much people eat
