Better test--which one stays the same?

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Prep4USMLE Forum » USMLE Step 2 CK Forum » Preventive Medicine

Better test--which one stays the same?

Author

9 Posts

lucci
Forum Senior

Topics: 35
Posts: 52

10/12/06 - 03:32 PM

A new test for CA Cervix allows better detection. Statistically all can be modified EXCEPT:

a. -Prevalence<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

b. -Incidence

c. -PPV

d. -NPV

e. -Survival rate

zhoufg
Forum Senior

Topics: 15
Posts: 112

10/13/06 - 10:20 AM

lucci
Forum Senior

Topics: 35
Posts: 52

10/13/06 - 04:19 PM

But shouldn't the survival rate go down because we detect the disease earlier and do the treatment earlier?

p00nam
Forum Newbie

Topics: 4
Posts: 13

10/22/06 - 05:15 AM

I think the answer will be A) .
Bcoz one cannot modify incidence rate statistically

dipsite
Forum Newbie

Topics: 1
Posts: 26

12/19/06 - 11:00 AM

hey you all succumbed to this question ..
my advice go through "high yield biostastics" textbook..the answer would be "incidence"...but listen above question states better detection which could be in terms of :- sensitivity or specificity..so mention..

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dipsite
Forum Newbie

Topics: 1
Posts: 26

12/19/06 - 11:14 AM

the question is not that easy..
let me present some facts..
see sensitivity,specificity of a test remains the same...but in the above case a new test has been introduced which has a higher detection rate so lets assume both sensitivity as well as specificity has increased..
increased sensitivity means detection of more number of cases increasing incidence as well as prevalence..PPV,NPV both are properties of a test so they both will change accordingly .. i am left with option (E)..

what is the answer ? with explanation ?

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vsp99
Forum Senior

Topics: 18
Posts: 74

12/19/06 - 02:22 PM

a - prevalence

robin082006
Forum Hero
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Topics: 471
Posts: 5,125

12/19/06 - 02:38 PM

I would select B. incidence

Better detection means increased sensitivity (not sure about specificity)

prevalence will be increased because early detection-->early treatment-->longer survival--> increased prevalence

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dipsite
Forum Newbie

Topics: 1
Posts: 26

12/20/06 - 10:36 AM

Nice logic but statistically is the key word..

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