A case-control study was conducted to evaluate the association between alcohol consumption

A case-control study was conducted to evaluate the association between alcohol consumption and cancer of the oral cavity. The crude analysis showed a strong association between the exposure and outcome: odds ratio= 4.5, 95% c·onfidence interval 3.4 - 5.6. Smoking was considered as a potential confounder of the association.Which of the following properties of smoking is essential in order to be considered as a confounder?

A. It should not be related to cancer of the oral cavity
B. It should be highly prevalent in the population of interest
C. It should be related to alcohol consumption
D. It should be observed only in alcohol consumers
E. It should be evenly distributed among alcohol consumers and non-consumers
correct answer C…Confounding is defined as mixing up of the effect of exposure with the effect of an extraneous factor (confounder). In order to be a confounder, the extraneous factor must have some properties linking it with the exposure and outcome of interest. In this example, smoking is the possible confounder. Smoking is related to the exposure (i.e.,people who consume alcohol are more likely to smoke), as well as the outcome of interest (i.e., smoking, by itself, is associated with cancer of the oral cavity). If smoking is the confounder, it explains at least part of the association observed between alcohol consumption and cancer of the oral cavity.