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What prevention reduces the occurrence of disease. takes place during prepathogenesis
Primary prevention
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what prevention reduces the progress of disease. Takes place during the pathogenesis phase of natural history of disease
secondary prevention
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What prevention limits disability from disease. the disease has occurred and has been treated but some form of rehab limits progression or minimizes side effects
Tertiary prevention
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What does screening do
- sorts out those who are at risk and those who are not
- do not diagnose but identify risk
- is preliminary and results must be confirmed by a diagnosis
- secondary prevention is screening happens
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What is the purpose of screening and what instruments can be used
- to separate those who "might" from those who "don't" have disease
- instruments: lab test, thermometer, scales, questionnaires
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What is Content validity
- used to measure the validity of survey instruments
- the items in a questionnaire seem to be valid for measuring what they are supposed to measure
- Also referred to as rational or logical validity
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What are the two types of validity under Criterion-referenced
- predictive validity
- concurrent
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what does criterion-referenced mean
found by correlating a measure with an external criterion of what's being assessed
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What is predictive validity under criterion-referenced
- ability to predict some attribute
- positive correlation with future incidence
- also know as statistical validity
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What is concurrent validity under criterion-referenced
- correlating a measure with an alternative measure of the same phenomenon taken at the same point in time
- ie: inversion and hospitalization for breathing problems OR inversion and depression
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It is possible for a measure to be highly _______ but not _______ BUT it is not possible for a measure to be ________ and not __________
- reliable
- valid
- valid
- reliable
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What are three sources of unreliability and invalidity
- Measurement bias
- halo effect
- social desirability
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What is measurement bias in connection with sources of unreliability and invalidity
constant errors that are introduced by a faulty measuring instrument
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What is halo effect in connection with sources of unreliability and invalidity
a general opinion has been formed prior to conducting an evaluation (like yearly evaluations by supervisors)
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What is social desirability in connection with sources of unreliability and invalidity
answer questions in manner that corresponds to what may be the socially desired behavior
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What is sensitivity as a measure of validity
- ability of the test to identify correctly all screened individuals who actually have the disease
- screened positive and have disease
- has to do with the tool used
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What is specificity as a measure of validity
- the ability of a test to identify only non diseased individuals who actually do NOT have the disease
- non diseased and test negative
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If screening test are unable to perform sensitivity and specificity what happens?
- cases are missed OR
- those who do not have the disease will be referred for additional diagnostic testing (which could cost lots of money)
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What is predictive value (+)
proportion (so talking about the actual number) of individuals screened positive by the test who actually have the disease (according to the gold standard)
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What is predictive value (-)
measure for those screened negative by the test and do not have the disease
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What is the epidemiologic triangle
- at the three corners are HOST, AGENT (disease/cause), ENVIRONMENT
- this model helps explain the etiologic agent, reservoir, portal of exit, transmission, portal of entry, and susceptible host
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What are the 6 characteristics of ID Agents
- infectivity
- pathogenicity
- virulence
- toxigenicity
- resistance
- antigenicity
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What is infectivity as a characteristic of ID agent
ability to enter and multiply in host and produce infection
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What is pathogenicity as a characteristic of ID agent
ability to cause disease in host
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what is virulence as a characteristic of ID agent
severity of disease
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what is toxigenicity as a characteristic of ID agent
capacity to produce a toxin
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what is resistance as a characteristic of ID agent
ability of disease agent to survive adverse environmental conditions (resistance versus fragile)
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What is antigenicity as a characteristic of ID agent
ability to induce antibody production in host
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What does "active" mean in connection with disease specific defense mechanisms
administer to host to mimic natural infection with little or no risk
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What is natural active
immunity from infection
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What is artificial active
infection with vaccine
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What does "passive" mean in relation to disease specific defense mechanisms
antibody for short duration
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What is natural passive
like pregnancy
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What is artificial passive
given to exposed individual to protect against developing disease (ie immunoglobulin)
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What is direct transmission as a mode of transmission in the environment and examples of how this happens
- person to person contact
- sexual contact
- respiratory infections
- blood borne
- fecal oral
- requires a way out (portal of exit), mode of transmission, and a way in (portal of entry)
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What are the characteristics of an Attack Rate (which is a measure of disease outbreaks)
- also an incidence rate
- the # of new cases among all exposed during a time period
- ALWAYS used in foodborne outbreaks
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What is the effect or exposure to a chemical or substance upon an organism
Dose-Response (exposure(dose))
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What is the lowest dose at which a particular response may occur
Threshold
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What is the time period between initial exposure and a measurable response
Latency
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what is the combined effect of several exposures
synergism
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Dose Response
At what level or concentration of the dose does the organism respond
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Threshold
- The accepted exposure level below which no adverse effects are observed
- Knowing the threshold of an exposure is a major assumption when determining the dose-response relationship fro an exposure
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Latency
Similar to incubation time.
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Synergism
The combination has a greater effect upon health than the sum of the two independent exposures
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Human body has 2 environments? what are the barriers?
- inside and outside
- Skin
- Gastrointestinal tract (gets it out)
- Lungs (cough)
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Types of variables
- Independent
- Moderating/Intervening
- Dependent/Outcome
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What is an independent variable?
- similar to exposure variable -- a causal factor
- stress, social incongruity, person-environment fit, life events
- The things that life throws at us
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What is a moderating/intervening variable
- also known as an intermediate variable
- variables in the causal pathway between the independent and outcome variables
- What we are made up of, what we have going for us
- personality factors (type A behavior)
- Culture
- social support
- lifestyle and behavior
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Dependent/outcome variables
- variables affected by an independent variable
- result of the independent and moderating variables
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What is the independent variable of social incongruity
- when out of place
- looking at effects of changes in residence; intra-generational mobility; husband-wife discrepancy in status
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what is included in dependent or outcome variables and some topics covered
- include physical health, mental health, and affective states
- some topics:
- life and job dissatisfaction
- mental health and stressors
- premorbid psychologic factors and cancer
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dependent/outcome variable: mental health and stressors
- depressed persons reported more physical illness than non-depressed
- psychologic disorders: posttraumatic stress disorder and major depression
- affective states: depressive symptoms
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What are characteristics of a good screening test
- Simple
- Rapid
- Inexpensive
- Safe
- Acceptable
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What is construct validity
The degree to which the measurement agrees with the theoretical concept being investigated
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Define Validity
also known as accuracy. It is measuring what you intend to measure. It give a true measure
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Three types of validity
- content
- criterion referenced (predictive validity, concurrent)
- Construct
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How do you improve sensitivity
the cut point to classify diseased should be moved farther in the range of the non diseased
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How do you improve specificity
the cut point should be moved farther in the range of typically associated with the disease
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When the _______ of a disease falls the ________ falls and the ____________ rises. Why important
- prevalence
- predictive value (+)
- predictive value (-)
- Any individual who has a positive screening test would have low probability of having the disease and an invasive or expensive diagnostic procedure would probably not be warranted
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What is indirect transmission
- spread through an intermediary source
- Vehicle water, food
- fomite (inanimate object, door knob)
- Vector - living insect or animal
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