In an early study of myocardial infarction (MI) and lifetime alcohol use, there was an association reported between exposure and disease that led the investigators to suspect heavy drinking was linked to MI. The data from this case-control study are as follows: 

Heavy Drinking        MI      Control 

Yes                            71                52 

No                             29                48

a ) Compute the overall odds ratio and interpret it in words.

 

Heavy drinkers are often heavy smokers, so the data from the case-control study were stratified by current smoking status:

 Heavy          Non- Smokers      Smokers 

Drinking       MI    Control        MI      Control 

Yes                  8          16           63         36 

No                   22         44           7           4

 

b) Is there an association between smoking and MI?

 

c) Is there an association between smoking and drinking?

 

d) Compute the odds ratio for each stratum (each smoking group).

 

e) From the analysis so far, discuss whether you consider smoking a confounder, an effect modifier, or neither? What would be the appropriate effect measure to describe the association(s)?

 

f) State your conclusions regarding the association between heavy drinking and MI in light of your findings of the role played by smoking in this study.