q3 - zkadhem

[ArchivalUser]

A hypothetical study examining the association between serum
cholesterol (>280) and cardiovascular disease (CVD) demonstrates a crude relative risk of 3.0. When the data is stratified by gender, the relative risk for men is 4.0 and the relative risk for women is 1.0. The adjusted risk is 3.0. The most appropriate interpretation of the results of this study is that
a. Gender is both a confounder and
an effect modifier
b. Gender is a confounder only
c. Gender is an effect modifier only
d. Gender is neither a confounder nor
an effect modifier
e. Gender is causal pathway

[ArchivalUser]

aa

[ArchivalUser]

aa

[ArchivalUser]

think again

[ArchivalUser]

8-49. The answer is c. Since the crude and the gender-adjusted relative risks are the same, we can conclude that gender is not a confounder (using the changein-estimate definition of confounding). However, the relative risk for men is different than for women. We conclude that gender is an effect modifier.Effect modification is a different concept than confounding. Confounding is a nuisance factor that needs to be eliminated because it causes a distortion
of the results, simply because the factor in question is distributed unevenly in exposed and unexposed individuals. Effect modification provides important information: the magnitude of the effect of a particular exposure on the outcome will vary according to the presence of a third factor”in this case, gender. It is not related to the fact that there may be more men than women in one group or another. A third factor can be both a confounder and an effect modifier if the adjusted risk differs from the crude risk, in addition to having different risks in women and in men. It may be neither a confounder nor an effect modifier if the adjusted and crude risks are the same and if the rates in men and women are the same. Finally, it could be only an confounder if the crude and adjusted risks differ, but the rates between men and women are the same. Stratification can be used to evaluate both confounding and effect modification: it will eliminate confounding and describe effect modification.

[ArchivalUser]

good q zkadhem...thanks!!

[ArchivalUser]

ur welcome