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#1




Absolute Risk Reduction and Number Needed to Treat?
In a study,
100 patients received medication X to prevent the development of diabetes and 200 patients did not receive the medication, 10 patients in the experimental group and 40 patients patients in the control group developed diabetes, what is the absolute risk reduction and number needed to treat? 
#2




Quote:
40/200= 0.2 ARR= 0.20.1= 0.1 NNT= 1/ 0.1= 10 
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#4




Abste risk reduction
absolute risk reduction = 10/100  40/200 = 10/100
I.e. 10 patients for every 100 patients will not have the disease compared to placebo NNT= 100/10 = 10 patients i.e. Fir every 10 patients receiving the drug 1 will have benefit Last edited by alaahoda2001; 12082011 at 04:25 PM. 
#5




Correct answer.

#6




Thank u guys that was nice discussion.
Can anybody tell me what's the relative risk reduction here? For the same question?
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#7




Vin31md: Nicely done but calculation is wrong...the answer should be negative to make sure ur doin it right...
its risk reduction...... 0.1 > 10% reduction a/(a+b) / c/(c+d) > 0.1  0.2 = 0.1 
#8




Quote:
The initial question asked Number Needed To Treat ( NNT ) . For NNT formula is : NNT= 1/Absolute Risk Reduction = 1/ARR = 1/(c/d)(a/b) . For Numbers Needed to Harm The formula becomes : NNH = 1/Atributable risk = 1/a/(a+b)c/(c+ d) 
#9




Quote:
ARR= Control Event rate  experimental event rate ARR =40/20010/100=0.20.1=0.1 NNT=1/0.1=10 10 people need to be treated to prevent one diabetes case development 
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BiostatisticsEpidemiology, Step1Questions 
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