Lecture 12: Evidence Evaluation Observational studies 1 Flashcards
What is the goal of descriptive epidemiology?
To exam patterns (of disease, health behaviours)
What is the goal of Analytic epidemiology?
To evaluate relationships between risk/protective factors and disease
What is the big picture for Analytic Epidemiology?
Is there a relationship (association)?
Exposure -> outcome
Exposure can be: drug (ex. statin), intervention (ex. diet), policy (ex. drug plan coverage)
Outcome can be: clinical measure (ex. cholesterol), disease outcome (ex. occurrence of cancer), patient satisfaction
What are the goals of experimental epidemiology?
To evaluate effect of treatment/intervention on disease
What kind of study design do descriptive and analytic epidemiology come under?
Descriptive and Analytic
What comes under experimental epidemiologic study designs?
Randomized controlled trial and non-randomized
In observational studies where are individuals followed (observed)?
Real-world settings
In observational studies is there any intervention/exposure assignment by researcher?
No
An analytic observational study what does it describe?
Describe relationship between exposure and outcome
Is disease the exposure or outcome in an analytic study?
Can be either or
An analytic observational study can evaluate?
An intervention, though not assigned by researcher
An analytic observational study start includes
Defined hypothesis
An analytic observational study ends with
Confirming or rejecting hypothesis
In analytic epidemiologic studies what is population? Is it larger than the sample
Who we want to learn about
Yes
In analytic epidemiologic studies what is the sample?
Who we will study
What is a cohort study? and what is the starting point?
Observational, analytic study
- Starting point is exposure
What does cohort mean?
Ancient Roman military unit, band of warriors
* Persons banded together
* Group of persons with common defining characteristic
Steps of a cohort study
- Identify exposure status
- Follow individuals over time to see who develops outcome
Cohort study flow
Look on slides
What criteria is included in exposure of a cohort study flow
What, how, when
What criteria is included in outcomes of a cohort study flow
What, when
What is the key to a cohort study?
Participants are followed up to that outcomes so researchers know when that outcome occurred
Measures of association in cohort studies are?
- Relative risk/Risk ratio (RR)
- Odds ratio (RO)
Interpretation of RR to see if there is a relationship?
RR>1 - Association: Exposed group have higher risk of outcome than unexposed group
RR = No association
RR<1 - Inverse association - Exposed group have lower risk of outcome than unexposed group
Interpretation of RR to see what is the strength of relationship?
RR > 1 - % increase = (RR -1) x 100
RR < 1 - % decrease = (1 - RR) x 100
What are the advantages to a cohort study?
- Can establish incidence
- Can examine rare exposures
- Can study multiple outcomes
What are the disadvantages in a cohort study?
- Lengthy and expensive
- Not suitable for rare outcomes
- Vulnerable to non-response, migration, loss to follow-up
