2 questions from nmbe

[Fatalis]

question about changing the defn of a positive tb test from being 10mm to 5mm
how will this affect incidence and prev? [incr, decr, no change]
-could someone please explain how this will effect the prev and incidence. I originally put it would increase the incidence and not change prev but it was wrong [i see why]

Here is the next question in a nut shell
study done with a new drug that decreases the duration of HSV by one week
what will this do to prev or incidence
a) incidence decr by 1/2
b) indidence doubles
c) prev decr by 1/2
d) prev x2
-again can someone provide me with a good explanation, this stuff is tricky sometimes

thanks!

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[Ionian]

Dude, I had the first question on my CBSE, where did you get it from?

I haven't reviewed biostats, I had chosen decreased incidence, increased prevalence.

I believe the question was, in patients that were immuno-compromised they had to change the sensitivity of the test. Guess they would have less of a response you know.

I'm pretty sure I answered it wrong.

 

[Fatalis]

it was on nmbe 11, no you are correct. I thought about it and it makes sense now. If you decr the test from 10mm to 5mm more people will test positive and that will increase both incidence and prev [logically it makes sense lol]

 

[Mednomad]

second one: prevalence has to decrease?

 

[Missorleans]

Second one would increase prevalence, as long as we're talking about HSV vesicle eruption and not just HSV infection. That question would annoy me if I got it on a real thing.

 

[Fatalis]

it was talking about the duration of the infection. why do you say prev increases?

 

[ArmyTiger]

Second one would increase prevalence, as long as we're talking about HSV vesicle eruption and not just HSV infection. That question would annoy me if I got it on a real thing.

I'm no biostatistics major, but I think you mean incidence, not prevalence. HSV only spreads during reactivations, and it sounds like the this drug shortens the reactivation period. Less transmissability --> less new infections --> less incidence

 

[Fatalis]

thats what I put as well and it was wrong, the decreases the prev. by 1/2...still dont have a clue as to why

 

[Missorleans]

I'm no biostatistics major, but I think you mean incidence, not prevalence. HSV only spreads during reactivations, and it sounds like the this drug shortens the reactivation period. Less transmissability --> less new infections --> less incidence

Yes, I was not paying attention to what I was writing. A drug that shortens the duration of an eruption would decrease prevalence. Actually, HSV can be spread when asymptomatic, but reducing the reactivation time might decrease incidence as well.
Again, not sure how much knowledge of HSV is assumed in this question.

 

[Mednomad]

fatalis.....which nbme is this from?

 

[Fatalis]

11
i didnt want to put the number at first bc of the copyright issues...iam not really sure the rules on this forum about it, so just played it safe