Analytic Epidemiology (14) Flashcards
Contrast descriptive and analytic epidemiology
[Descriptive/Analytic] epidemiology is used to evaluate the causality of associations and relies on development of new data
Analytic
What is a hypothesis?
What is a null hypothesis?
assume there is no association between exposure and outcome
What is the purpose of an analytic study?
to test the null hypothesis and either reject it or find it acceptable
What are the types of analytic studies?
observational
interventional
What is an observational study? Is it descriptive or analytic? Give examples
no intentional control of exposure
analytical
ecological studies
cohort studies
case-control studies
What is an interventional study? Is it descriptive or analytic? Give examples
exposures are controlled/known
clinical studies (random assignment)
community studies (non-random exposures)
What are ecologic studies?
a study in which the units of analysis are populations or groups rather than individuals
What are the advantages of ecologic studies?
may provide information about the contributors of health
can be performed when individual-level measurements are NOT available
can be conducted rapidly
What are disadvantages to ecologic studies?
imprecise measurement of exposure
usually hypothesis generating
temporal ability
confounding
ecologic fallacy
What does this show?
temporal sequence is not clear
What is ecologic fallacy?
associations observes at the group level do not necessarily hold true at the individual level
opposite is another type of fallacy -exception fallacy
What is a cohort?
defined as a population/group that shares a particular exposure and is followed over time to observe changes in outcome
What are types of cohort studies?
prospective cohort study
retrospective cohort study
What is a prospective cohort study?
subjects (screened to be outcome-free) are followed into the future to document the occurrence of new cases
What is a retrospective cohort study?
makes use of historical data to determine exposure level after some baseline in the past
Regardless of cohort study type, the measure of association in cohort studies is the _____
relative risk (RR)
What is the framingham heart study?
prospective cohort study
analyzed patterns related to cardiovascular disease
What are the advantages and disadvantages of prospective and retrospective cohort studies?
What are case-control studies?
subjects are defined on the basis of the presence of absence of an outcome of interest (usually a disease)
cases have the disease; controls do not
What are advantages and disadvantages of case-control studies?
What are intervention studies?
the investigator intentionally changes some form of exposure between several groups to determine differences in outcome
What is a randomized clinical trial?
subjects are recruited from am population and randomly allocated into groups, usually called study and control groups
What is a cross-over clinical trial?
study progresses and groups are switches
What is a community trial?
intervention designed for the usual purpose of educational and behavioral changes at the population level
When is relative risk used?
used when comparing outcomes of those who were exposed to something to those who were not exposed
cohort studies and randomized clinical trials
What is relative risk?
a measure of the strength of association based on cohort studies and randomized clinical trials
What is the equation off relative risk?
incidence exposed/incidence unexposed
a/a+b / a/c+d
How do you calculate odds ratio?
ad/bc
If a RR or OR is greater than 1, what does this mean?
exposure may be positively associated with disease
How big should the RR or OR be for us to be impressed?
cohort study: RR > 3 for a minor adverse event
case-control: OR > 4
What is external validity?
refers to one’s ability to generalize the results of the study to an external population
What is internal validity?
refers to the degree to which the study has used methodologically sound procedures
if a study is designed in such a way that the differences between the case and control groups are totally attributed to the treatment applied, the study is said to have great internal validity
What is the hawthorn effect?
type of bias
participant’s nehavorial changes as a result of being in a study
What is a healthy-worker bias?
observation that employed populations tend to have a lower mortality experience than the general population
What is ‘false POSITIVE’
type 1 - reject null hypothesis which is actually true
What is ‘false negative’?
type II - accept null hypothesis when it is actually false
