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52 Cards in this Set

  • Front
  • Back
3 stages in epidemiological research
descriptive
analytic
experimental
a typical descriptive study
survey
2 typical analytic studies
cohort
case-control
3 phenomena assessed in analytic epidemiology
host
agent
environment
4 typical host factors
genetics
behavior
immunological state
age
numerator for period prevalence
total cases at beginning + all new cases
prevalence can be thought of as ___ times ___. an example of this is ___.
incidence
duration
rise in HIV prevalence after tx became available
incidence is useful for measuring ___ and assessing ___. it is used in ___ (2) studies
risk
disease etiology
clinical trials
cohort
prevalence is useful for ___. it is used in ___ (2) studies.
planning health services
cross sectional
case-control
cumulative incidence is ___ divided by ___.
# of new cases during a time period
population at risk at the beginning
incidence rate is ___ divided by ___.
number of new cases observed
total person-time of observation
3 aims of descriptive epidemiology
describe natural history of disease
determine allocation of resource
suggest hypotheses about disease causes
direct age adjustment uses the ___ rates from a specfic population and applies them to the ___ population to obtain a ___ rate.
age-specific
standard
age-adjusted
2 kinds of studies
descriptive
analytical
2 kinds of analytical studies
experimental
observational
3 prospective studies
clinical trial
cohort
historical prospective
___ is the most common way to estimate risk
cumulative incidence
T/F: at the beginning of a cohort study, some of the cohort has the disease
false
the risk measure in a cohort study or ___ is ___. it is the ratio of ___ to ___.
randomized control trial
relative risk
incidence with exposure
incidence without exposure
etiology of disease is assessed using risk ratio/difference
ratio
T/F: cohort studies are suitable for rare diseases
false
5 disadvantages of cohort study
expensive
large sample needed
takes long time
not suitable for rare diseases
bias due to high dropout rate (loss to follow-up)
single blinding means
patient doesn't know whether they're in tx or control
double blinding means
patient and person treating them don't know whether pt is in tx or control
triple blinding means
pt, person treating them, and data analyst don't know
number needed to treat (NNT) in terms of absolute risk reduction
NNT = 1/(ARR)
in case-control studies, ___ is used to approximate relative risk
odds ratio
formula for odds ratio
OR = (cases exposed*controls not exposed)/(cases not exposed*controls exposed)
in case-control study you should use ___ to measure cases
incidence
little improvement in precision is achieved once control/case ratio is above ___
4
4 disadvantages of case-control study
prone to recall bias
prone to selection bias in controls
only an approximation of risk
not suitable for rare exposures
in cross-sectional study risk is measured by ___ (2)
prevalence odds ratio
prevalence ratio
4 disadvantages of cross-sectional study
no temporal relationship
biased towards long-duration cases
no risk ratio
not suitable for rare diseases or exposures
T/F: systematic error does not decrease with increased sample size
true
3 sources of systematic error
selection bias
information bias
confounding
3 a priori criteria for confounders
risk factor for disease
associated with exposure in source population
NOT an intervening variable in the causal pathway
3 ways to control confounding in experiment design
restriction of study
randomization
matching
3 ways to control confounding in data analysis
restriction of analysis
stratification
multivariable regression
validity is aka
accuracy
reliability is aka ___ (2)
repeatability
precision
___ is a function of systematic errors
validity
___ is a function of random errors
reliability
___ errors are reduced with increasing n
random
T/F: bias only affects external validity
false
1st 5 of Hill's criteria for causality
strength of association
consistency of association
specificity: single effect of exposure
temporality
biological gradient (dose-response)
last 4 of Hill's criteria for causality
biological plausibility
coherence with literature
experiment
analogy
___ determines the gain from performing a test
difference between pre-test and post-test probabilities
pre-test probability is estimated by ___
prevalence
post-test probability is estimated by ___ if test is positive, ___ if test is negative
PPV
1-NPV
solution to lead-time bias in evaluating screening programs is ___
solution to length-time time bias in evaluating screening programs is ___
use mortality instead of survival time
use RCT
screening test should have high ___
sensitivity
specificity
PPV
recall bias is an example of ___ bias
measurement/infomation