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#1
05-23-2011
 USMLE Forums Master Steps History: 1 + CK Posts: 623 Threads: 62 Thanked 289 Times in 186 Posts Reputation: 299
Number Needed To Treat Calculation?

a study is done to see if raloxifene will reduce the incidence of vertebral fractures in post menopausal women.
Results are
RALOXIFENE --- PLACEBO
no. of women in study group 2557 --- 2576

no. of vertebral fractures 138 --- 260
(5.4%) --- (10.1%)

based on these results how many women need to be treated to prevent one vertebral fracture?

A) 100/5.4=18.5
B) 100/10=10
c) 100/10+5.4=6.5
D) 100/10-5.4=21
E) 100/10*5.4=2
 The above post was thanked by: bebix (05-23-2011)

#2
05-23-2011
 USMLE Forums Guru Steps History: Not yet Posts: 324 Threads: 70 Thanked 239 Times in 144 Posts Reputation: 249

its D.
NNT= 1/absolute risk reduction.
Absolute risk reduction =event rate(control)-event rate(tt)
=10.1%-5.4%
=4.7%=0.047
NNT=1/ARR
=1/0.047
=21.2
#3
12-17-2011
 USMLE Forums Veteran Steps History: Not yet Posts: 281 Threads: 74 Thanked 132 Times in 69 Posts Reputation: 142

The answer to this question according to NBME feedback is E, although cannot understand why??????

#4
12-18-2011
 USMLE Forums Scout Steps History: 1 + CS Posts: 79 Threads: 19 Thanked 33 Times in 11 Posts Reputation: 43

D ans..in which NBME ??
#5
12-18-2011
 USMLE Forums Veteran Steps History: Not yet Posts: 281 Threads: 74 Thanked 132 Times in 69 Posts Reputation: 142

NBME 7,its answer E,cannot understand how but

 Tags Biostatistics-Epidemiology, Step-1-Questions

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