Term
Descriptive Epidemiology works with?
- key tools |
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Definition
outbreak investigation
surveillance
public health
key tools:
sampling
counting prevalence
incidence risk
incidence rate |
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Term
| Definition of Epidemiology |
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Definition
| study of the frequency, distribution and determinants of disease in populations and the applications of this study to control health problems |
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Term
| Briefly list 5 ways to measure morbidity/mortality |
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Definition
counts
ratios
proportions
risks
rates |
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Term
Proportion is written as?
- discuss numerator and denominator |
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Definition
written as decimal, fractions or percentages
numerator is part of denominator
ie 300 females/400 total students |
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Term
risk is measured in?
expresses what? |
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Definition
proportions
expresses probability that something will occur.
ie probability of getting flu shot last year = got flu/total pop |
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Term
Rates express what?
measures what? |
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Definition
expresse occurrence of event in defined population in a specified period of time.
measures "speed"
ie incidence rate is 14 cases per 1000 person-years |
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Term
| Case where 3 million cattle in july, 7500 farms and 500 cases of anthrax. give appropriate amount in counts, ratios, proportions and rates |
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Definition
| count: 500 ratio: 1:6000 proportion: 0.02% rates: 2 cases per 10,000 cattle months at risk |
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Term
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Definition
used in census and surveys
problem: no denominator so don't know how bad it is |
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Term
proportion of group diseased
-formula
-used in? |
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Definition
| number with disease (a)/ number (n) "at risk" of disease denominator (n) includes numerator (a) a/(a+b) used in census or sample |
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Term
| prevalence -measured in? -units and range? - does it measure risk? why/why not? |
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Definition
| prevalence relates to number of existing cases of disease of interest in population (at a certain point or period) - measured in proportion - has no units and ranges from 0 -->1 - is NOT a measure of risk because it doesn't take into account duration of disease or when disease occurred. The numerator includes individuals with disease that is of varying durations. |
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Term
Point Prevalence
- formula |
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Definition
proportion of population that has disease of interest at a particular time
point prevalence = number with disease at single point in time/ number in pop that can actually get disease at that point in time |
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Term
Period prevalence
- formula |
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Definition
Proportion of population that has disease of interest during certain period
period prevalence = number with disease during specific time period/ number in population that can actually get disease during that period of time |
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Term
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Definition
when an observation is stopped because of
end of study
person left cohort
was lost to follow up
or
died from cause OTHER than one of interest |
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Term
Incidence
-measures
-requirements
- give two formals for determining |
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Definition
a dynamic measure of disease occurrence
new disease occurs over time
- measures speed
- requires two or more observations or tests. the first to establish which individs are disease free, the second to identify which ones became diseased in intervening period.
- two formulas:
risk: new cases/population at risk
rate: new cases/ sum of person-time at risk |
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Term
| difference between risk and rate when measuring incidence? |
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Definition
they have the same numerator, but different denominators.
risk measures new cases/population at risk
and
rate measures new cases/sum of person-time at risk |
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Term
risk aka cumulative incidence aka incidence risk
- measured in?
- units, range?
- formula |
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Definition
proportion of unaffected individuals, who, on average, will develop disease of interest over a specified time period
- measured in proportion
- no units, range 0-1
- risk = # new cases in population during specified time period/ initial NAR - 1/2 withdrawals during time period.
- NAR = number at risk (must have potential to become case at time 0)
- Withdrawals = individs that leave study for other reasons, but did not develop disease of interest. |
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