Evidence hierarchy

Abstract

Decision-making requires a delicate balance between values, expertise, resources and knowledge. Evidence is the objective dimension of knowledge which can be exploited for decision-making. As the human brain complexity is quite evident, so are evident the complexity and multifaceted feature of evidence informing decision-making in clinical medicine as well as in many different fi elds of humanity. In particular different sources of evidence can be identifi ed, from less robust, precise and accurate to others which are more robust, more precise and more accurate. Yet, there is a continuum in the hierarchy of evidence, and it would be naive to think that less formal sources of evidence should be disregarded altogether in comparison to more established and robust ones (i.e. randomised controlled trials). Similarly, other layers of evidence on top of randomised trials can be envisioned going to systematic reviews, to meta-analyses and to umbrella reviews. Only the explicit and conscientious integration of such multiple sources of evidence in a unifying framework can lead to effective and effi cient decision-making.