The population etiologic fraction for a particular disease from Factor X alone is five times greater than that from Factor Y alone. If the relative risk associated with Factor X is 2, and with Factor Y is 20, which of the following statements is true?
A) The risk of developing the disease is greater in those exposed to Factor X only than in those exposed to Factor Y only.
B) Fewer persons are exposed to Factor Y than to Factor X.
C) The proportion of the disease in the population attributable to Factor Y is greater than that attributable to Factor X.
D) More persons are exposed to Factor Y than to Factor X.
E) The risk of developing the disease for persons exposed to Factor Y is five times greater than for persons exposed to Factor X.

Question

Quizplus · Accepted Answer

The population etiologic fraction is influenced by both the relative risk and the prevalence of exposure. Since the relative risk for Factor Y is much higher than for Factor X, the fact that the etiologic fraction for Factor X is greater suggests that more people are exposed to Factor X than to Factor Y.

The Population Etiologic Fraction for a Particular Disease from Factor