Step I Biostats q on UsmleRx flashcard

[greenseeking]

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A drug reduces flu incidence from 1 in 45 pts to 1 in 90. How many people must get the drug to prevent 1 new case?

Answer key-
The answer is 2. the number needed to treat = (1/absolute risk reduction), or in this case, 1/0.5, or 2

My answer-
I got 90. NTT=1/ARR where ARR= 1/45-1/90=1/90. So, NTT=1/(1/90)). Can anyone point out where I'm going wrong? Thank you!

 

[TheBoneDoctah]

A drug reduces flu incidence from 1 in 45 pts to 1 in 90. How many people must get the drug to prevent 1 new case?

Answer key-
The answer is 2. the number needed to treat = (1/absolute risk reduction), or in this case, 1/0.5, or 2

My answer-
I got 90. NTT=1/ARR where ARR= 1/45-1/90=1/90. So, NTT=1/(1/90)). Can anyone point out where I'm going wrong? Thank you!

Is this the entire question? Idk why the answer is not 91.


Sent from my iPhone using SDN mobile app

 

[greenseeking]

Is this the entire question? Idk why the answer is not 91.


Sent from my iPhone using SDN mobile app

Yup that's the entire question. I got 90 ... so I guess the answer key is wrong.

 

[mw18]

Yup that's the entire question. I got 90 ... so I guess the answer key is wrong.

Yeah, you're right. The absolute risk reduction would have to be fifty percent of the total people at risk for the number needed to treat to be 2. Like if flu went from 75/100 to 25/100.

 

[greenseeking]

Yeah, you're right. The absolute risk reduction would have to be fifty percent of the total people at risk for the number needed to treat to be 2. Like if flu went from 75/100 to 25/100.

Thank you!!