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Old 09-30-2012
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Stats Incidence and Prevalence denominator?

Hi guys,
Im a little confused about what the 'denominator' includes for Incidence and Prevalence ?
Is the Denominator the present cases+those at risk?
So, what I'm asking is if Incidence = a/a+c?
if 'a' is the new identified cases and 'c' are the ones with no disease, but at risk of getting the disease??

Thanks in advance!
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Old 09-30-2012
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Incidence=new events in population(eg;A)/population at risk(ie A which is new events as above and old cases are not counted)

Population at risk does not involve the new cases since they already have disease & no longer at risk of being infected.
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Old 10-01-2012
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Quote:
Originally Posted by blade View Post
Incidence=new events in population(eg;A)/population at risk(ie A which is new events as above and old cases are not counted)

Population at risk does not involve the new cases since they already have disease & no longer at risk of being infected.
That's what I thought so. But I googled it and it says Prevelance and Incidence denominators is "the entire population".

Also, I think it was when I was doing the KLN videos that he mentions that the denominator includes the present cases+the 'at risk' ones..

Any thoughts?
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Old 10-01-2012
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A state with a population of 4000,000 contains 20,000 people who have disease A,a fatal neurodegenerative condition. There are 7000 new cases of the dx a yr and 1000 deaths attributable to dx A. There are 40000 deaths per yr from all causes. what is the incidence of the dx?

A. 8000/3,933,000
B. 7000/3,933,000
C. 7000/3,980,000
D. 8000/3,980,000
E. 28,000/3,970,000

Uworld q.
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Old 10-02-2012
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Aah! I see where I'm getting confused now.The answer is C

But will the prevalence be 20000/4000,000?
So the prevalence denominator includes the entire population while the incidence has only the 'at risk' ones.

Am I right?
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Old 10-02-2012
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C is correct & you are right on prevalence
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