c0uld s0me 0ne explain this biostastical qn...thnx - USMLE Forums
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#1
04-18-2014
 USMLE Forums Newbie Steps History: Not yet Posts: 8 Threads: 5 Thanked 0 Times in 0 Posts Reputation: 10
c0uld s0me 0ne explain this biostastical qn...thnx

biostastics
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#2
04-18-2014
 USMLE Forums Scout Steps History: Not yet Posts: 64 Threads: 13 Thanked 1 Time in 1 Post Reputation: 11

yuk.....this qn is making my head go in circles!
:
#3
04-18-2014
 USMLE Forums Guru Steps History: --- Posts: 338 Threads: 54 Thanked 139 Times in 92 Posts Reputation: 149

Cool question, where did you get if from?

So it sounds super difficult, with all the information given... but in fact I think it is super easy.

The ask for the Number needed to treat which equals 1/absolute risk reduction

The risk for both groups is given: 2,3% and 1,3% respectively

so the NNT = 1 / (2,3% - 1,3%) = 1/0,01 = 100

pretty straight forward if I got it correct

Last edited by Curacao; 04-18-2014 at 05:04 AM.
 The above post was thanked by: Ltnsd (04-19-2014), tolles (04-18-2014)
#4
04-18-2014
 USMLE Forums Scout Steps History: Not yet Posts: 64 Threads: 13 Thanked 1 Time in 1 Post Reputation: 11

Quote:
 Originally Posted by Curacao Cool question, where did you get if from? The risk for both groups is given: 2,3% and 1,3% respectively pretty straight forward if I got it correct
why is it 2.3 n 1.3 thats being considered?
ARR is absolute risk of placebo-absolute risk of rx..
.
er... i think i just understood what u meant.

just for clarity, could u put those values into the 2x2 table? (disease x risk), the plus n minus n all..?
#5
04-18-2014
 USMLE Forums Addict Steps History: Not yet Posts: 129 Threads: 15 Thanked 29 Times in 20 Posts Reputation: 39

this is an nbme 12 question so may spoil the assessment for someone the poster should have mentioned it and imo the answer is 2.3 since attributible risk reduction here is 2.3 minus 1.3 divided by 2.3 we get 1 divided by 2.3 as the attributable risk reduction if we inverse this we get 2.3 which is the number needed to treat correct me if i am wrong
 The above post was thanked by: mihirkakara (12-29-2014)
#6
04-18-2014
 USMLE Forums Guru Steps History: --- Posts: 338 Threads: 54 Thanked 139 Times in 92 Posts Reputation: 149

Thanks for the person posting the thread spoiling an NBME12 questions

By the way, this question can be answered using google and has also been discussed in this forum before...

nbme behav
#7
04-18-2014
 USMLE Forums Guru Steps History: --- Posts: 338 Threads: 54 Thanked 139 Times in 92 Posts Reputation: 149

Quote:
 Originally Posted by dr rookie why is it 2.3 n 1.3 thats being considered? ARR is absolute risk of placebo-absolute risk of rx.. . er... i think i just understood what u meant. just for clarity, could u put those values into the 2x2 table? (disease x risk), the plus n minus n all..?

well there's no 2x2 table to set up, it is already in the question. It asks for the prevention of one congenital anomaly.

The risk of all congenital anomalies in women taking
Trace Elements is 2,3%

ARR: 2.3% - 1.3% = 1%

NNT = 1/ARR = 1/1% = 1/0,01 = 100
 The above post was thanked by: dr rookie (04-18-2014)
#8
04-18-2014
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 592 Threads: 92 Thanked 195 Times in 127 Posts Reputation: 205

Quote:
 Originally Posted by Curacao Thanks for the person posting the thread spoiling an NBME12 questions My answer 100 is correct By the way, this question can be answered using google and has also been discussed in this forum before... nbme behav
PLEASE people if youre putting NBME questions on the forum be considerate AND LET US KNOW.... geez....

awesome curacao, i got cold sweat when i saw this question
in fact it IS EASY, "its always a TRAP" i have to keep myself repeating this for my exam hahaha, thanks for your explanation in fact it is 100.
__________________
Will. Power. Faith. MATCHED IM 2016!
#9
04-18-2014
 USMLE Forums Newbie Steps History: Not yet Posts: 8 Threads: 5 Thanked 0 Times in 0 Posts Reputation: 10

s0rry guys !!
fr0m next time i will label it as an nbme qn
anyways thanx f0r great ans wid explanati0n
#10
12-29-2014
 USMLE Forums Newbie Steps History: Not yet Posts: 1 Threads: 0 Thanked 0 Times in 0 Posts Reputation: 10
Question lingers

Hi guys, I'm brand new. Sorry to dredge this up, but why, if the question asks for a congenital abnormality, do we not include neural tube defect and say NNT = 1/((2.3+.29) - 1.3) = ~80?

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