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 USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam

#1
04-25-2015
 USMLE Forums Scout Steps History: Not yet Posts: 15 Threads: 5 Thanked 5 Times in 4 Posts Reputation: 15
Biostats

hii!!

I have a question... this is what I understood from kaplan... are NNT and NNH calculated the same way?

Example:
incidence of cancer in smokers: 10/100
incidence of cancer in non smokers: 1/100

Attributable risk:
10-1= 9/100

NNT/ NNH:
100/9= 11

so in that example I assume the NNT and NNH are the same

is that accurate?

NNT: number needed to treat
NNH: number needed to harm

#2
04-26-2015
 USMLE Forums Addict Steps History: Step 1 Only Posts: 142 Threads: 27 Thanked 51 Times in 33 Posts Reputation: 61

Number needed to treat(NNT) is calculated based on the absolute risk reduction(ARR), it is inverse if ARR. Basically this is where we talk about how many patients we should treat to PREVENT one case of disease.(Question will talk about placebo treatment vs new treatment)

Number needed to harm(NNH) is calculated based in attributable risk(AR), it is inverse of AR. This is how we calculate how many people need to be exposed to a risk factor to DEVELOP one case of disease. (Question will talk about risk factor exposure)
 The above post was thanked by: Kruno (03-11-2016), Marķa Zavala (04-26-2015), pncdoc (09-11-2015), zak09 (03-12-2016)
#3
04-26-2015
 USMLE Forums Scout Steps History: Not yet Posts: 15 Threads: 5 Thanked 5 Times in 4 Posts Reputation: 15

Thanks so much Hassanah

I didn't find absolute risk reduction on kaplan... where did you read it from? or maybe i misread it

#4
04-26-2015
 USMLE Forums Addict Steps History: Step 1 Only Posts: 142 Threads: 27 Thanked 51 Times in 33 Posts Reputation: 61

Yeah its not mentioned in kaplan but you can read it from First Aid.
 The above post was thanked by: Marķa Zavala (04-27-2015)
#5
03-11-2016
 USMLE Forums Veteran Steps History: 1+CK+CS+3 Posts: 285 Threads: 32 Thanked 86 Times in 71 Posts Reputation: 96

Number needed to treat is calculated by dividing 1 by the absolute risk reduction --> 1/([C/C+D]-[A/A+B])

Number needed to harm is calculated by dividing 1 by the attributable risk --> 1/([A/A+B)-[C/C+D])

i would upload flashcards of this, but i dont have enough posts do so. if you have an android, you can check out the flash cards on an app called EpiStats. its an app im working on and trying to improve.
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#6
1 Week Ago
 USMLE Forums Scout Steps History: --- Posts: 24 Threads: 18 Thanked 1 Time in 1 Post Reputation: 11

Memorizing formulas for ARR and NNT is probably not a good idea. In terms of working with data, it's better to get the concept so if you have to work with data that is presented in different forms, you can still work wit them
#7
1 Week Ago
 USMLE Forums Veteran Steps History: 1+CK+CS+3 Posts: 285 Threads: 32 Thanked 86 Times in 71 Posts Reputation: 96

Here are the flashcards for number needed to treat and attributable risk. Check out the video lectures if you want a guide on how to make the calculation.

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Last edited by Kruno; 1 Week Ago at 03:17 AM.
#8
5 Days Ago
 USMLE Forums Scout Steps History: --- Posts: 24 Threads: 18 Thanked 1 Time in 1 Post Reputation: 11

I have made 3 minute long, concise videos on these topics. I hope they help you, and also give me feedback on them:
https://youtu.be/9-_WICLuaCI
https://youtu.be/ZKO4lIY7yF0
#9
5 Days Ago
 USMLE Forums Scout Steps History: --- Posts: 24 Threads: 18 Thanked 1 Time in 1 Post Reputation: 11

Quote:
 Originally Posted by pharmacologybuil I have made 3 minute long, concise videos on these topics. I hope they help you, and also give me feedback on them: https://youtu.be/9-_WICLuaCI https://youtu.be/ZKO4lIY7yF0
Also if you have any other question or topic you want to go over, I would be happy to help
#10
5 Days Ago
 USMLE Forums Scout Steps History: 1+CK+CS+3 Posts: 16 Threads: 0 Thanked 0 Times in 0 Posts Reputation: 10

Research opportunity in Houston Texas. Training and hiring ...

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