Study Designs - Lecture Eighteen Flashcards
Measures of Association
How do we find associations?
Through analytic study designs using PECOT or GATE
Analytic study designs
Cross-sectional studies Ecological studies Cohort studies Case-control studies Randomised controlled trials
PECOT
Population Exposure Comparison Outcome Time
Population
The group of people in the study
Exposure
What the potential determinant is
Comparison
What the potential determinant is being compared to
Outcome
The health outcome being assessed
Time
How long people are being followed-up
Relative risk
How many times as likely is the exposed group to develop the outcome than the comparison group
Risk difference / attribution risk
Ie-Ic
How many extra/fewer cases of the outcome in the exposed group are attributable to the exposure?
Interpreting risk difference
“There were value extra/fewer cases of outcome in exposed group compared to comparison group”
Relative risk VS Risk difference
Relative risk gives clues to causes and strength of association, whereas, risk difference gives impact of exposure and the impact of removing exposures
How do we know if an exposure is associated with an outcome?
Compare development of outcome in people with the exposure with development of outcome in people without the exposure
Compare the amount of people who get lung disease who smoke versus
the amount of people who get lung disease who dont smoke
Measure of association
Ratio of the incidences: relative risk
Differences in the incidences: risk difference or attributable risk
Ratio of the incidences: relative risk
equation
Exposed/Comparison
With a null value of 1
