relative risk reduction - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

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


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 03-02-2016
USMLE Forums Scout
 
Steps History: Not yet
Posts: 32
Threads: 19
Thanked 2 Times in 2 Posts
Reputation: 12
Angry relative risk reduction

you are designing a study to evaluate efficacy of new drug km28. your study will compare km28 plus standard care vs standard care alone in decreasing the incidence of recurrent breast cancer. the FDA will approve the new drug if km28 plus standard care reduces the rate of breast cancer recurrence by 40% compared to standard therapy alone. the recurrence rate on standard therapy is found to be 8%. in order for km28 to be approved, what is the maximal incidence of recurrent disease acceptable for women treated with km28 plus standard therapy?
A. 5.2%
B. 4.8%
C. 3.6%
D. 3.2%
E. 2.8%

guys i am not understanding how the relative risk reduction formula is applied here and what is relative risk reduction? can someone explain in detail??
Reply With Quote Quick reply to this message



  #2  
Old 03-02-2016
USMLE Forums Scout
 
Steps History: Not yet
Posts: 84
Threads: 1
Thanked 50 Times in 35 Posts
Reputation: 60
Default

Quote:
Originally Posted by anamta View Post
you are designing a study to evaluate efficacy of new drug km28. your study will compare km28 plus standard care vs standard care alone in decreasing the incidence of recurrent breast cancer. the FDA will approve the new drug if km28 plus standard care reduces the rate of breast cancer recurrence by 40% compared to standard therapy alone. the recurrence rate on standard therapy is found to be 8%. in order for km28 to be approved, what is the maximal incidence of recurrent disease acceptable for women treated with km28 plus standard therapy?
A. 5.2%
B. 4.8%
C. 3.6%
D. 3.2%
E. 2.8%

guys i am not understanding how the relative risk reduction formula is applied here and what is relative risk reduction? can someone explain in detail??
You do not have to use the formula if you do not want to. You calculate 40% of 8=3.2% and then subtract 3.2 from 8=4.8%

That would give you a number which is 40% less than 8, which is what they are asking.

You can use the formula where RRR=1-RR.

RRR=40%=0.4
RR=new drug+standard of care/standard of care=x/8
You do not have to use 0.08 instead of 8% in the RR equation since it has no effect on the ratio as long as you keep in mind that the answer you get will also be in percentages.

0.6=x/8
x=8*0.6
x=4.8

You can see how much more calculations you have to do if you decide to go with the formula as opposed to reasoning it out yourself. On some of those questions formulas are more time consuming. Although, if you have the time it is always better to use the formula to double check your reasoning.

Relative risk reduction just says what percentages of cases you prevented (or cured, or whatever) with your intervention.
Reply With Quote Quick reply to this message
The above post was thanked by:
anamta (03-03-2016)
  #3  
Old 03-03-2016
USMLE Forums Scout
 
Steps History: Not yet
Posts: 32
Threads: 19
Thanked 2 Times in 2 Posts
Reputation: 12
Default

thanks nodo
Reply With Quote Quick reply to this message
 
  #4  
Old 04-01-2016
USMLE Forums Veteran
 
Steps History: 1+CK+CS+3
Posts: 274
Threads: 31
Thanked 86 Times in 71 Posts
Reputation: 96
Default

Quote:
Originally Posted by anamta View Post
you are designing a study to evaluate efficacy of new drug km28. your study will compare km28 plus standard care vs standard care alone in decreasing the incidence of recurrent breast cancer. the FDA will approve the new drug if km28 plus standard care reduces the rate of breast cancer recurrence by 40% compared to standard therapy alone. the recurrence rate on standard therapy is found to be 8%. in order for km28 to be approved, what is the maximal incidence of recurrent disease acceptable for women treated with km28 plus standard therapy?
A. 5.2%
B. 4.8%
C. 3.6%
D. 3.2%
E. 2.8%

guys i am not understanding how the relative risk reduction formula is applied here and what is relative risk reduction? can someone explain in detail??
Relative risk reduction is the decrease in incidence of a condition in one treatment group in comparison to another. In this question, you are given the relative risk reduction (40%) and the incidence of breast cancer in people on standard therapy (8%). What you need to do is enter the data into the equation for relative risk reduction and then solve for the incidence of breast cancer in the group of patients receiving km28.

Relative Risk Reduction = 1 - (Incidence in Group A / Incidence in Group B)
Relative Risk Reduction = 1 - [(A/A+B) / (C/C+D)]
40% = 1 - [(A/A+B) / 8%]
A/A+B = 60% * 8%
A/A+B = 4.8%
Attached Thumbnails
relative risk reduction-blue-punnet-cards.jpg   relative risk reduction-info-cards.jpg   relative risk reduction-big-title-cards.jpg  
__________________
Check out my
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
channel on youtube.
Reply With Quote Quick reply to this message



Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Absolute risk reduction versus Relative risk reduction koyi USMLE Step 1 Forum 9 11-23-2013 06:23 AM
Cardiovascular Risk Reduction tyagee USMLE Step 2 CK Forum 10 12-23-2012 11:37 PM
Absulote risk reduction, NNT and NNH firstaid150 USMLE Step 2 CK Forum 1 10-16-2012 07:49 AM
Hazards ratio, Relative risk Novobiocin USMLE Step 2 CK Forum 0 06-12-2012 01:55 PM
Calculating the relative risk ratio? riya10 USMLE Step 1 Forum 7 03-01-2012 02:23 PM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)