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Old 08-16-2012
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Stats Calculation of Attributable Risk?

In a small observational study, 100 industrial workers are followed for one year to assess for the development of respiratory symptoms (defined as productive cough lasting at least one week). 30 of 60 smokers experience respiratory symptoms over the year versus 10 of 40 non-smokers. What percentage of respiratory disease experienced by all study subjects is attributed to smoking?

A) 75%
B) 50%
C) 25%
0) 20%
E) 10%
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Old 08-16-2012
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draw 2 by 2 table

Dx No Dx
Smok 30 30
Non Smok 10 30

hence 30/40=75%
option Aa
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Old 08-16-2012
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Quote:
Originally Posted by imgchuchu View Post
draw 2 by 2 table

Dx No Dx
Smok 30 30
Non Smok 10 30

hence 30/40=75%
option Aa
oops, distorted table. let me try again

...........................Disease;.........No disease
..........smokers......30;.................30..... ....
..........Non smokers.10;.................30.........
......... Total diseas..40

percentage attributable to smoking 30/40=75%
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Old 08-16-2012
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risk of disease in smokers minus the risk of disease in non smoker

30/60 minus 10/40 = 25%
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Old 08-16-2012
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Default my answer

C)25%

agree with viral's calculations
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Old 08-17-2012
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Attributable risk= Incidence of dx - incidence of non dx
So, 30/60 - 10/40 = 1/4= 25%
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Old 08-17-2012
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wow, hope I don't make this nasty mistake in exam
I was calculating sensitivity instead of AR
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