Epidemiology Flashcards
(49 cards)
What is epidemiology?
The study of the occurrence and distribution of health-related events in specified populations, including the study of the determinants influencing such states and the application of this knowledge to control the health problems
What is descriptive epidemiology?
describing patterns of health and disease in populations
What is analytical epidemiology?
Identifying why some populations or individuals are at greater risk of disease and hence identify the risk factors
Give the PICO process
P – patient, problem or population (What is the problem to address? Identification of the target population)
I – intervention (Risk factor under investigation)
C – comparison, control or comparator
O – outcome (Disease/Health state)
Define the term ‘ecological study’
An observational study where the exposure and/ or disease is observed at a group level. The group is the unit of observation e.g. the group may be defined as hospital/ health region etc.
Define the term ‘cross sectional study’
A snapshot of the frequency of diseases and exposures in a particular population at a specific time-point.
Define the term ‘cohort study’
An observational study which identifies a group of people and follows them over a period of time to determine incidence of, or mortality from, specific disease(s) and see how their exposures affect their outcomes.
What are case control studies?
A retrospective study which compares how frequently the exposure to a risk factor is present in a group of individuals who have a specific disease (case) and in another group of individuals without the disease (control)
What’s the problem with observational studies?
Multiple factors can contribute to a disease and some factors only have an indirect relation to the disease. In observational studies, we only observe. There’s no control on who is exposed, what, how, when.
Define the term ‘randomised controlled trial’
A study in which a number of similar people from a target population are randomly assigned to 2 or more groups to test a specific drug, treatment or other intervention.
Why are RCTs the gold standard for research?
Randomisation allows to create two comparable groups with the exception of the received treatment.
Control of potential confounders and other influential factors as two groups equally affected.
No selection bias induced by the recruiter to favour one treatment over the other
Why is epidemiology important in making public health decisions?
Epidemiological studies show what’s healthy/unhealthy, which then influence government policy
What are in vivo studies?
Studies done in living organisms
What are in vitro studies?
Studies performed or taking place in a test tube, culture dish, or elsewhere outside a living organism.
Why are in vivo and in vitro studies limited?
The effects shown in animals are possibly different to the effect in humans
Cells behave differently outside the body compared to within the body
Strengths of case-control studies
Good quality data as it was collected specifically for the study
Relatively quick and cheap to conduct- no long periods of follow up
Can study multiple exposures and outcomes
Efficient for rare outcomes
Weaknesses of case-control studies
Temporal sequence is unknown (can’t be sure if exposure came before outcome)
Prone to bias, both selection and measurement
Confounding factors that are related to exposure and outcome that explain the association
Can not calculate incidence rates
Inefficient for rare exposures
Define the term ‘confounder’
A confounder (also confounding variable, confounding factor or lurking variable) is a variable that influences both the dependent variable and independent variable causing a spurious association.
Define the term ‘mediator’
A mediator is a variable that causes mediation in the dependent and the independent variables. In other words, it explains the relationship between the dependent variable and the independent variable.
Describe experimental design studies
Full control of who is exposed, and of the different exposure factors (observed or not).
Describe observational design studies
Exposure are not assigned by the researcher, only the observed exposure can be investigated, no control on the unobserved exposure.
What are cases in case-control studies?
Someone with the thing that you’re investigating
What are controls in case-control studies?
Individuals who would have been cases if they had developed the outcome
Odds ratio
An odds ratio (OR) is a measure of association between an exposure and an outcome.
The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure.
