Question

Describe how epidemiologists view the Hill causal criteria, briefly mentioning: (a) how is it like evidence introduced into a court case? (b) Is there a minimum of how many of the causal criteria are necessary to fulfill in order to demonstrate it is likely exposure is associated with disease? (c) is it possible in epidemiologic studies to prove that an exposure causes a disease (why or why not, very briefly)?

Answer 1

The Bradford Hill criteria or Hill's criteria for causation, are a group of 9 principles that can be useful in establishing epidemiologic evidence of a causal relationship between a presumed cause and an observed effect and have been widely used in public health research.

Epidemiologist's conclusion about HIll's causal criteria is that their value has been questioned because they have become somewhat outdated and their method of application is debated.Some proposed options how to apply them include:-(i)Subdividing them into three categories: direct, mechanistic and parallel evidence, expected to complement each other (ii) Using Hill’s criteria as a guide, but not considering them to give definitive conclusions.(iii) Considering confounding factors and bias.

Hill’s nine aspects of association were never intended to be viewed as rigid criteria or as a checklist for causation.As the world of epidemiologic research has changed and expanded, our criteria for determining causal inference must similarly evolve.The advanced tools and techniques that have developed in recent decades have affected the application and interpretation of the Bradford Hill criteria.This involves incorporating not just traditional epidemiological evidence but also evidence gathered by opening the ‘black box’ and incorporating data from molecular biology, toxicology, genotoxicology, and other disciplines into evaluations of causation.

(B) Minimum crieteria are the first three criteria are generally considered as requirements for identifying a causal effect: (1) empirical association, (2) temporal priority of the indepen- dent variable, and (3) nonspuriousness. You must establish these three to claim a causal relationship.

(C) It is not possible in epidemiological studies to prove that an exposure cause a disease  that is, it cannot prove that a specific risk factor actually causes the disease being studied. Epidemiological evidence can only show that this risk factor is associated with a higher incidence of disease in the population exposed to that risk factor.