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Old 04-13-2014
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Default NBME 11 Question


I have a question about the Tuberkulin Skin Test qs where they changed the cutoff from 10mm to 5mm and asked for Incidence and Prevalence.

I got the question right but now I still keep overthinking it.
I chose Incidence and Prevalence both increase.

In Kaplan Qbank there were a lot of questions dealing with increase/decrease cutoff so I figured a change from 10mm to 5mm will decrease the cutoff and more people get positive results.

decrease cutoff -> increase sensitivity, decreased specificity, increase NPV, decrease PPV

and PPV is positive related with Prevalence this would mean: decrease PPV -> decrease Prevalence.

I am clearly overthinking it... so where is my mistake.

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Old 04-14-2014
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y r u going in such depth? they just asked abt change in prevalence & incidence ryt?

so whn u dec the cutoff the chances that more ppl will be tested +ve will inc. thus the incidence will inc. & since the inc. will inc. so this will make the dis more prevalent hence prevalent inc.

hope this helps..
Never let your fear be stronger than your Faith
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