Abstract
Evidence-based medicine is a means of conducting scientific research and deriving conclusions from a background of evidence strongly supported by properly- conducted and effectively unbiased studies. It is a fundamental principle of decision- making and data evaluation in credible scientific work, as well as modern medical practice.
Causality and causal inference is a widely investigated example of the application of evidence-based medicine in research. The most notable out of the earliest theories of causal association was formulated by Robert Koch in the field of microbiology.
The postulates are as follows; (i) the pathogen must be present in all cases of the disease, (ii) the pathogen must allow for isolation from host and be grown in pure culture, (iii) the cultured pathogen should cause disease when introduced into a healthy host, (iv) the pathogen from the new host must be isolated and once again grown in pure culture to be validated as being identical with the initial etiologic agent of the disease. Advancements in the field of microbiology have proven several limitations of Koch's overgeneralized postulates.
Hence, his postulates were largely replaced 50 years later by a more extensive guideline published by Bradford Hill. The guideline, otherwise known as Hill's criteria, is comprised of 9 principles describing causal relationships; strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment, analogy.
Hill's criteria are still applicable in modern scientific research, as demonstrated in recent studies conducted on the causality of high dietary cholesterol on cardiovascular diseases, PCBs on carcinogenesis and postnatal secondhand tobacco exposure on neurobehavioral disorders.