When risk factors combine: The interaction between alcohol and smoking for aerodigestive cancer, coronary heart disease, and traffic and fire injury

Background: Alcohol and tobacco are responsible for a significant amount of burden of disease, but some diseases may be a result of the interaction between these two risk factors. Methods: Systematic literature review identified articles on the interaction of alcohol and smoking on a number of outcomes related to both risk behaviours. Results: The interaction of smoking and alcohol significantly increases risk for aerodigestive cancers, and may increase risk for traffic injury and fire injury, but there were very few quality studies on injury. The indication that the cardioprotective effect of alcohol on coronary heart disease is only valid for smokers, but this result is inconclusive because of small evidence base. Conclusions: The interaction between smoking and alcohol consumption seems to be responsible for a significant amount of disease. Unfortunately, little is known on the mechanisms and details of this interaction on disease outcomes. Future studies, especially for coronary heart disease and injury outcomes, are warranted.