nbme form 4 question help - putin

[ArchivalUser]

a study is done to determine if raloxifene will decrease the incidence of vertebral fractures in postmenopausal women. The results are shown:

number of women in study group Raloxifene 2557 , Placebo 2576

number of verterbal fractures 138 260
(5.4%) (10.1%)

How many women need to be treated to prevent 1 vertebral fracture?

A. 100/5.4=18.5
B. 100/10.1=10
C. 100/(10.1+5.4)=6.5
D. 100/(10.1-5.4)=21
C. 100/(10.1 x 5.4)=2

[ArchivalUser]

Raloxifene (2557 women) and 138 vertebral fractures = 5.4%

Placebo (2576) and 260 fractures = 10.1%

[ArchivalUser]

D.21
number of patients need to be treated ( NNT) = 1/ absolute risk reduction ( ARR)=1/10.1-5.4=21

[ArchivalUser]

thanks, dream88!

I also answered D, but the answer was stated E) 100/(10.1 x 5.4)=2 ....and i really beleive, that it's wrong. UW bank was giving answer like yours.