In a cohort study of smoking and myocardial infarction in City A,the number of myocardial infarctions were 250 cases among 7,000 smokers and the number of myocardial infarctions were 150 cases among 20,000 nonsmokers.What is the attributable risk (risk difference) of smoking?
A) 2.8 per 1,000
B) 3.6 per 1,000
C) 7.5 per 1,000
D) 28.2 per 1,000
E) 35.7 per 1,000

Question

Quizplus · Accepted Answer

The attributable risk,risk difference,equals the incidence in the exposed minus the incidence in the nonexposed.In this study,the incidence of myocardial infarction among smokers is 35.7 per 1,000 and the incidence among the nonexposed is 7.5 per 1,000.Subtracting the latter from the former,the difference in the incidence rate is 28.2 per 1,000.

In a Cohort Study of Smoking and Myocardial Infarction in City