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34 Cards in this Set
- Front
- Back
Vital statistics registry systems describes what?
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events
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US Census describes what?
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the population
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Fundamental epidemiologic measure describes what?
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the occurrence of an event of interest in a population
Define the measure and the population Reproducible and generalizable |
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What is a count?
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the number of individuals who meet the event definition (e.g., 213,867 cases of breast cancer)
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to describe a fundamental epidemiologic measure, how do you normally do it?
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with a fraction
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to describe a fundamental epidemiologic measure we use a fraction, what do the numerator and denominator mean respectively?
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Numerators (typically the eventof interest)
-------------------------------- Denominators (typically the populationof interest) |
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Describe the difference btw ratio, proportion, and rate
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Ratio: X/Y
Proportion: X/(X+Y) Rate X at a point in time/ X+Y at the same point in time |
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What are the 3 uses for 2x2 tables?
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1.
Clinical diagnostic testing 2. Calculating epidemiologic measure 3. Hypothesis testing |
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using a 2x2 table, how would you calculate the risk of disease if exposed?
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A
---------- A + B A=number of people exposed with disease B=number of people exposed withOUTdisease |
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using a 2x2 table, how would you calculate Risk of disease if UNexposed
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C
---------- C + D C=number of people NOT exposed with disease D=number of people NOT exposed withOUTdisease |
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using a 2x2 table, how would you calculate Odds of Disease
If exposed |
A
--- B A=number of people exposed with disease B=number of people NOT exposed with disease |
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using a 2x2 table, how would you calculate Odds of Disease
If UNexposed |
C
---- D C=number of people NOT exposed with disease D=number of people NOT exposed withOUTdisease |
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What is point versus period prevalence?
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if a disease is present at a certain point or over a longer duration (period)
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What are crude rates? give an example
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Rates that apply to an entire population, without regard to any specific characteristics
• E.g., Which country has the highest crude mortality rate: USA, Sweden, or Equador? – CMR = # deaths / mid-period population |
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what are specific rates? please give an example
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Population is divided into smaller homogenous subgroups (e.g., age-specific mortality rate)
• ASMR = # deaths people of certain age group / # people age group |
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What is an adjusted (or standardized) rate?
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Crude rates that have been adjusted to account for (control for) the effects of some other variable (e.g., age) to allow for a more valid comparison
• E.g., compare the ASMRs of two populations to a fictitious “standard” population |
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what does prevalence measure?
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the presence of disease that exists in population at a given time
This value is a proportion [ P = X / (X+Y)], where X = disease |
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what is Point prevalence
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Measures presence of disease at a specific point in time
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what is period prevalence?
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Measures the presence of disease throughout a specified period of time
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what is incidence of disease?
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measures the occurrence of new cases of disease over a given time
This value is a rate [ I = X / (X+Y)], where X = disease or case Y=ppl without the case |
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what is Cumulative incidence
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All individuals in the population are at risk for the outcome over the entire period of study
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what is Incidence density
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All individuals in the denominator of the rate fraction were not followed for the same length of time
The rate includes a time component referred to as “person-years” |
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for incidence what is the denominator of the fraction
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the denominator of the fraction is comprised of all people in the population who are at risk of developing disease
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what is the fraction used for incidence?
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ppl that become diagnosed with a case
-------------------- those at risk of getting the disease |
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Be able to calculate Incidence Density Rate, the number of person years by looking at a graph
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SEE SLIDE 22 on Epi Measures lecture
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Prevalence vs Incidence
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incidence will increase prevalence
so you will hvae a baseline prevalence, as you add new cases (increase incidence) you will increase prevalence If people start dying you will decrease prevalence (as well as population, which is in both numerator and denominator) |
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development of new cases, immigration/emigration, and average duration of disease state all influence what?
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prevalence
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Prevalence=?
THIS WILL BE ON THE TEST |
Incidence X Duration (average)
P = I X D |
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what is attack rate?
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is a “special” type of incidence rate in which the time period is specified implicitly rather than explicitly
Typically related to an outbreak in which a proportion of the population is exposed and develops the outcome |
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rate of food poisoning within a population of people exposed to “bad” food
this is an example of what? |
Attack rate
Cases that develop months after the incident (e.g., exposure to contaminated food) are not considered part of that particular outbreak |
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Case-Fatality Rate =
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# deaths from lung cancer in one year
---------------------------------- # people with lung cancer in that year percentage of people with disease that die of the disease in given time |
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Proportionate mortality
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Proportion, not a rate
Of all the deaths in a population, what proportion are caused by disease “X”? |
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Proportionate mortality for X=
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# deaths from X in 2002 in USA
---------------------------------------------------- total # of deaths in 2002 in USA expressed as percentage (so x100) |
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Crude Birth Rate=?
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# live births in 2002 in USA
------------------------------------------- mid-period population in 2002 in USA |