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40 Cards in this Set
- Front
- Back
VALIDITY
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the ability of a test to detect who does and does not have disease
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SENSITIVITY
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the ability of a test to ID correctly who has the disease of interest
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SPECIFICITY
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the ability of a test to ID correctly those who do not have the disease of interest
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RELIABILITY/REPRODUCTIBILITY
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extent to which results obtained by a test are replicated if the test is repeated
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WHAT IS THE KEY ASSUMPTIOIN FOR SCREENING?
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early detection leads to a more favorable prognosis
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Screening is more like a ____ test that tells you whether you should go on for another test or not.
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crude
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When you screen people for disease, are they symptomatic or asymptomatic?
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asymptomatic
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Why do we screen participants?
Name 3 reasons. |
1. to favorably modify the natural history of disease
2. improve morbidity 3. reduce mortality |
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Disease with _____ consequences are appropriate for screening.
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serious
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Disease where tx is given ____ sxms is more beneficial than tx given ____ are more appropriate for screening.
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before, later
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Disease where prevalence of detectable preclinical disease is ____ in population to be screened is more appropriate for screening.
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high
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Name 6 characteristics that make a screening test suitable.
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1. inexpensive
2. easy to administer 3. well-tolerated 4. valid 5. reliable 6. reproducible |
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Draw example of 2x2 screening table.
Explain in a legend what a,b,c,d represent |
Early Disease ("truth") (top)
Screening Test (side) a b c d a= true positives b=false positives c=false negatives d=true negatives |
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PREDICTIVE VALUE POSITIVE
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probability of having disease given you have a positive screen
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PREDICTIVE VALUE NEGATIVE
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probability of not having disease given you have a negative screen
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Maximize sensitivity at expense of specificity then you:
Decrease false ______, but yield false _______ |
negatives, positives
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Choose to increase sensitivity when penalty for not identifying cases is ____
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high
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choose to increase sensitivity when disease is _____.
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serious
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choose to increase sensitivity when _______.
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treatment exists (if it doesn't exist, do you want to know you have disease?)
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choose to increase sensitivity when _______.
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disease can be spread
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choose to increase sensitivity when _______.
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subsequent dx has minimal costs and risks
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choose to ____ specificity when penalty for incorrectly identifying someone as case is ____
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increase, high
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Name 3 ways that we can assess whether the screening program works or not.
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1. follow up with those who tested positive
2. assess cost per case detected 3. asses how many of those who test positive have the disease (PV+) |
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PV+ is influenced by _____, _____, and ______ of the detectable preclinical phase of the disease.
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sensitivity, specificity, prevalence
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PV+ is most influenced by ____ and ____
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sensitivity, prevalence
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How do you increase prevalence?
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target populations at high risk
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Name 3 biases specific to screening.
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1. volunteer
2. lead-time 3. length |
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VOLUNTEER BIAS
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people who choose to be screened will be different from those who do not.
these people are usually healthier with lower mortality rates "the worried well" |
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LEAD-TIME BIAS
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cases detected by screening appear to survive longer due to their earlier dx
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what does lead-time mean?
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the duration by which the diagnosis of disease is moved forward in time among each case detected by the screening program
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LENGTH BIAS
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cases with a longer detectable preclinincal phase and thus a more favorable prognosis tend to be overrepresented among screen detected cases
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BASIC PRINCIPLES OF MASS SCREENING:
Condition should be _______. |
an important public health issue
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BASIC PRINCIPLES OF MASS SCREENING:
should be accepted ____ for pts with disease |
effected treatment
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BASIC PRINCIPLES OF MASS SCREENING:
if no tx, then ____ |
do not screen
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BASIC PRINCIPLES OF MASS SCREENING:
adequate ____ and ___ facilities should exist |
dx, tx
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BASIC PRINCIPLES OF MASS SCREENING:
Natural history of condition should ___ understood |
reasonably be
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BASIC PRINCIPLES OF MASS SCREENING PROGRAMS:
it should be ID in ____ or ___ sxm stage |
latent, early
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BASIC PRINCIPLES OF MASS SCREENING PROGRAMS:
Should (not be/be) invasive |
not
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BASIC PRINCIPLES OF MASS SCREENING PROGRAMS:
Screenigns hould be a ________ rather than a _____ program--people get upset if it's taken away |
continuing process, temporary
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BASIC PRINCIPLES OF MASS SCREENING PROGRAMS:
Screening program shoul dbe shown to be effective in reducing ____, ____ from the disease--though this isn't always the case |
morbidity,mortality
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