fabrilosu
Forum Newbie
Topics: 8
Posts: 18
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About 1% of boys are born with undescended testes. To determine whether prenatal exposure to tobacco smoke is a cause of undescended testes in newborns, the mothers of 100 newborns with undescended testes and those of 100 newborns whose testes had descended were questioned about smoking habits during pregnancy. The study revealed an odd ratio of 2.6 associated with exposure to smoke, with 95% CI from 1.1 to 5.3.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Some reviewers are concerned that the study may overestimate the association between maternal smoke and undescended testes in the offspring because of potential
a. Confounding
b. Non-differential misclassification
c. Differential misclassification
d. Selection bias
e. Loss to follow up
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| robin082006
Forum Hero
Topics: 471
Posts: 5,125
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A
Smoking may be associated with drinking, making the study have counfounder.
___________________
The Key to Succeed is Patience.
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| babydoc4usmle
Forum Guru
Topics: 18
Posts: 634
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agree, A
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| Clozapine
Forum Elite
Topics: 15
Posts: 167
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C . Differential Misclassification
Possibly due to recall bias, moms with kids w/undescended testes will give more accurate info regarding their smoking habits than the control group.
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| Clozapine
Forum Elite
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Posts: 167
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whats the answer fabrilosu?
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| virgola82
Forum Guru
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Posts: 348
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Clozapine is right. I actually got it wrong and said A too while testing but the RIGHT ANSWER is C
Recall bias is a form of information bias and differential misclassification. Persons experiencing a bad outcome (e.g. a child with undescended testes) are more likely to search their past and prod their memory about potential causes for the occurence. Therefore in case-control studies, like this, differential misclassification can lead to a falsely high odd ratio.
It is said "differential" misclassification because recall bias (that is the misclassification) doesn't occur randomly in both cases and controls, as opposed to "Non differential" misclassification that occurs when the memory of an xposure is unrelated to the fact that the person develops a disease or not. "Non diferential misclassification" causes therefore the results to move toward the null (no association) that is the opposite effect than "differential"
Confounding occurs when the apparent effect of an exposure is partly or entirely due to a third factor associated with both exposure and outcome. Although a third factor could potentially be present here, it is not mentioned in the stem and therefore the main concern should be recall bias and thus differential misclassification
This q came from PreTest Preventive Medicine and Public Health
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