biostat Q - mony26175

[ArchivalUser]

1- In assessing the efficacy of natalizumab, in the treatment of multiple sclerosis (MS), a randomized double-blinded placebo-controlled study was performed with a total of 1000 people divided equally between the treatment and placebo groups. The study lasted for three (3) years and during this period, the reduction in relative risk for primary events (relapse of current MS or progression to a more chronic form of MS) was 8%. The absolute risk reduction was smaller because the study group had a low incidence of MS-associated events., 1% in the control group and 3% in the treatment group. How many patients must be treated for three years with natalizumab to prevent a primary event in one person?

A. 2
B. 1
C. 50
D. 100
E. 20

[ArchivalUser]

C

[ArchivalUser]

@monter plz explain how

[ArchivalUser]

ARR

3%-1% = 2%

NNT

2% or 1 in 50


FA page 50

[ArchivalUser]

i did not get it.......pl help

ARR= control- exposed/treated

but qs says control=1%, treated=3%

am i missing a point here..??

[ArchivalUser]

any one.........

[ArchivalUser]

NNT = 1ARR

ARR= incidence 1 - incidence 2 = 3% - 1% = 2% = 2/100

NNT = 1 2% = 1 (2100) = 1002 = 50

[ArchivalUser]

sorry it didn't post it as I wrote it. here I will write it again

NNT = 1 ARR

ARR= incidence 1 - incidence 2 = 3% - 1% = 2% = 2 / 100

NNT = 1 2% = 1 (2 100) = 100 2 = 50

[ArchivalUser]

Again it doesn't post it correctly I don't know why. anyway I think your problem is that when you calculate AAR you forget the (%). so you say ARR= 2 , but it not just 2 , it must be 2% with means 0.02

[ArchivalUser]

ARR= control- exposed/treated
is not Absolute risk reduction defined as above.??

i did not understand incidence1 and incidence2.

any one...??