Hierarchy of Evidence

Why it matters that you understand the inherent differences between evidence.

Figure 1. Hierarchy of evidence. Adapted [Copied] from Research Methods in Health: Foundations for Evidence Based Practice (p. 6), by P. Liamputtong, K. Anderson & T. Bondas, 2017, South Melbourne: Oxford University Press. Copyright 2017 by Pranee Liamputtong.

Commonly, hierarchical structures are the most commonly referred to pathway of evaluating research. Whilst, there is conjecture about the 'best' type of evidence, it really depends on the purpose of the research and the intended use within professional practice (Liamputtong et al., 2017). Similarly, there are some drawbacks in utilising the hierarchical structure above as it preferences quantitative over qualitative methodology, may ignore the limitations of randomised controlled trials and neglects studies of an observational nature (Liamputtong et al., 2017).

A point to consider as you read this before we head too much further. Can you simply describe what is undertaken at each level of the pyramid above? If not, I would encourage you to spend some time reviewing each aspect as this underpinning knowledge forms the basis of how we utilise evidence to inform clinical care. Why you might ask? Simply, because at the end of the day you need to know how to use the research and evidence, not how to create it.

A more simplified representation is offered below extracted from the Greenhalgh text in the setting of interventional studies. This figure represents the pathway that you should seek out research especially as it relates to clinical care within a discipline, starting from the top of the pyramid and working towards the bottom (if needed). Seeking out clinical practice guidelines and point of care resources, ultimately progressing towards the bottom of the pyramid and utilising expert opinion to form the basis of clinical care. Always keep the following question front of mind, what is best for my patient?

Figure 2. Hierarchy of evidence. Adapted [Copied] from Understanding Research Methods for Evidence Based Practice in Health (p. 67), by T. Greenhalgh, J. Bidewell, E. Crisp, A. Lambros & J. Warland, 2020, Milton: John Wiley & Sons. Copyright 2020 by John Wiley & Sons Australia, Ltd.

References

Greenhalgh, T., Bidewell, J., Crisp, E., Lambros, A., & Warland, J. (2020). Understanding Research Methods for Evidence Based Practice in Health (2nd Edition). ProQuest Ebook Central https://ebookcentral.proquest.com

Liamputtong, P., Anderson, K., & Bondas, T. (2017). Research Methods in Health: Foundations for Evidence Based Practice (3rd Edition).

ProQuest Ebook Central https://ebookcentral.proquest.com