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A questionnaire was administered to nurses who had a non-fatal myocardial infarc

ID: 2949799 • Letter: A

Question

A questionnaire was administered to nurses who had a non-fatal myocardial infarction (MI) about oral contracep (OC) use. They were age-matched to 3,120 controls (1 case per 20 controls) As per the selection criteria, all the participants were premenopausal and therefore could have been using OC. The two-by-two table shown below summarizes the relationship between OC and MI. Current OC use Yes No Total MI 23 133 156 Controls 304 2,816 3,120 Total 327 2,949 3,276 Using the numbers above, what is the effect of the association between OC use and the risk of MI? O a 0.6 O b. 1.0 Oc, 1.5 O d. 1.6

Explanation / Answer

Probability of MI if using OC = 23/(23+304) = 23/327

Probablity of MI if not using OC = 133/(133+2816) = 133/2949

Relative Risk = Probability of MI if using OC/Probablity of MI if not using OC

Relative Risk = (23/327)/(133/2949) = 1.6

This means that risk for myocardial infarction is 1.6 times higher in nurses using oral contraceptive.

Option D is correct