Observational Studies Flashcards
What is an observational study?
Where we observe the effect of an exposure or intervention on an outcome without interfering with anything
What does observational studies look for?
Looks for associations not causation
WHy do we utilize observational studies?
Practical/deasible
Ethical
Real-world
Major challenges with observational studies?
Chance
Confounding
Bias
What are the 3 or 4 main types of observational studies?
Case reports
Cross sectional
Case control
Cohort
WHat is a case report?
Describes and interprets an individual case where is looks at
- unexpected events, adverse effects,
What are the advantages of case reports?
Useful in identifying new or unusual trends in disease
Useful in identifying new drug effects
Describe novel interventions
Suggest ares of further research
What are the disadvantages of Case reports?
Difficult to interpret
Cant confirm or prove anything
What is a case series?
Collection of individual reports which typically occur within a fairly short period of time
Can be hypothesis forming or world altering
What is a cross sectional study?
Looks at a population for study sample at one point in time (Picture in that moment)
How do cross-sectional studies collect information?
Surveys
Chart reviews
Administrative data
What type of information is collected in a cross sectional study?
Exposure
Outcome
Health status
Health behaviours
What is a usefulness of a cross sectional study?
Describing prevalence of a disease condition
Can be analytical
What are the disadvantages of a cross sectional study?
Number of new cases with a condition over a specific time cannot be analyzed
What is a case control study?
These are retrospective cases where we look back in time and compare 2 groups.
Where do we start with a case control study?
What do we need to ensure when performing a case selection for case control study?
Needs to be very specific about the outcome since it really is the outcome we think about
For the control selection of a case control study what do we want?
We want the exposed and unexposed groups to be as simialr as possible except for outcome
What are the advantages of case control studies?
Good for studying rare diseases or outcomes
Relatively quick to do since outcome has happened
Good for establishing an association
What are the disadvantages of a case control study?
Not randomized hence confounding
Susceptible to bias
Only suggests association and cannot prove cause and effect
What is a cohort study?
groups of subjects are created and compared according to exposure
Groups followed over time to see if outcome occurs
What is the best type of observation study to utilize for finding a valid association?
Cohort study
What is a cohort prospective study?
We start at the start of the outcome where the outcome has not occurred
What is a retrospective cohort study?
Outcome occured before study started
What types of exposures can you study with a cohort study?
Any type of exposure
Drug
Procedure
Occupational
Environmental
What are the advantages of a cohort study?
provides a high level of evidence for observational studies
Can study multiple outcomes after a single exposure
disadvantages of a cohort study?
Susceptible to bias
Not randomized
more resource intensive
What occurs during cohort study selection?
Groups should be as similar as possible
Selected from same population
Can have more than one comparator gorup
What do we need to think about with respect to a cohort study?
The exposure must precede the outcome
