In Analytic Epidemiology we need to try and establish a rela

In Analytic Epidemiology we need to try and establish a relationship between exposure and outcome (disease). Sometimes a causal association can be made....A > B (A yields or leads to B), and other times a non-causal association. What is the difference and why does it matter? Please provide reference. I need this answered by the end of the day.

Solution

Non-casual association refers to linkage between exposure and the outcome as a matter of chance or random factor alone. This refers to the fact that exposure and outcome are associated with a confounding factor. On the other hand, the casual association between exposure and outcome is based on evaluation of entire criteria rather than any single factor. So, exposure always preceds the disease and any changes in exposure leads to corresponding changes in the outcome as well. Casual association between exposure and outcome skips the need of identification of particular causative agent for the disease to establish the treatment for the same. On the other hand, if there is non casual association, cause occurs after the outcome and the causative agent must be identified for establishment of the treatment.
Ref: http://www.who.int/bulletin/volumes/83/10/792.pdf