Populations- Prevalence And Cross Sectional Studies Flashcards
Prevalence?
Frequency of cases of a disease in a given population at a designated time.
Number of people with disease/ number of people who have disease
Point prevalence?
Prevalence at a point in time
Period prevalence?
Prevalence over a specific period of time
Lifetime prevalence?
Prevalence of the disease/condition ever in individuals lifetime
Types of risk factors?
- Demographic
- Behavioural
- Health-related
- Environmental
- Genetic
How to calculate prevalence?
Use contingency table
Case definition?
Criteria of identifying person i.e case of disease/outcome
Conditions for case?
Clearly defined and specificity Consistent within a study Comparable to other studies Reproducible Leading to interpretable and meaningful results
Ecological study?
Exposures/outcomes within populations
Cross sectional study?
Exposures/outcomes within individuals
Weakness of studies?
Not suitable for rare disease and diseases of short duration,
Can’t measure rate of new cases arising and changes,
Vulnerable to bias
Cross sectional studies -confounding?
Variable that influences exposure and outcome, dependent and independent variable
Benefits of different types of prevalence?
Point/period- better patient recall/tracking changes
Lifetime- short/fluctuating/epidosic conditions
Strengths of cross sectional and ecological studies?
Measure prevalence and compare in exposure and non-exposure, quick and inexpensive, inform hypotheses
Which prevalence to use in a study?
Point/ period - better for tracking change sin a population and fewer issues with bias arising from inaccurate participant recall
Lifetime- better for people affected by short term, episodic or fluctuating diseases
