Measures of Association Flashcards
Name types of descriptive studies?
- case reports
- case series
- cross sectional
- ecological
Name types of anaytical studies?
- case control studies
- cohort studies
- randomized control tables
- systematic reviews
- quasi-interventional studies
- ecological
Between descriptive and analytical which one is experimental?
descriptive studies are never experimental but analytic studies may or may not be experimental
Describe cohort studies?
start with exposed and not exposed then follow up for disease or no disease
- are used in studies of etiology
- It enables comparison of populations that have had a certain exposure to those with no exposure
Describe case control studies?
start with have the disease (cases) and do not have the disease (controls) then follow up with were exposed and were not exposed
- are also used to address questions of etiology
Describe experimental/intervention studies?
from a study population people are randomly assigned either the new treatment or a current treatment and see if improve or do not improve from each treatment
What are measures of association?
A measure of association quantifies the relationship between exposure and disease among the two groups
What are exposure factors?
refers to any factor that may be associated with an outcome of interest
e.g.
behaviour
genetic
time
person
place
environmental
social
What are 2x2 tables in epidmiology?
used to summarize frequencies of disease and exposure and used for calculation of association
The measures of association usually used in the design/studies are?
absolute risk difference and relative risk ratios or rates
1. Absolute
- Risk difference exposed - unexposed
2. Relative
Risk ratios
- Odds ratios exposed / unexposed
Note: Odds ratios are also used in cohort studies
What is relative risk/risk ratio?
- Relative risk compares the risk of an event among a specific group with the risk in another group.
- The exposed group is the group of primary interest while the comparison group is called unexposed group.
- Demographic factors as sex (e.g., males versus females) and exposure to a suspected risk factor (e.g., did or did not eat potato salad) differentiates the groups.
What is the equation for relative risk ratio?
- The ratio of the risk of disease in persons exposed compared to the risk in those unexposed
- Often, a measure of association between incidence of disease and exposure of interest
RR = incidence rate of disease in exposed/incidence rate of diseases in non-exposed
What is odds ratio?
Odds ratio is the ratio of the odds
of an exposure in the case group to the odds
of an exposure in the control group.
- Remember that Odds Ratios are usually higher than Risk ratios
Describe the interpretation of relative risk ratio?
If RR = 1, Risk in exposed equal to risk in non-exposed (no association)
If RR > 1, Risk in exposed greater than risk in non-exposed (positive association; possibly causal)
If RR < 1, Risk in exposed less than risk in non-exposed (negative association; possibly protective)
What are case control studies?
Studies are designed to determine if an exposure is associated with an outcome.
Note: Case-control studies are always retrospective – starts with an outcome then traces back to investigate exposures.