Being ‘evidence-based’ in the absence of evidence: The management of non-evidence in guideline development

Abstract

Since the emergence of the Evidence-Based Medicine (EBM) movement, the nature and role of evidence in medicine has been much debated. The formal classification of evidence that is unique to Evidence-Based Medicine, referred to as the Evidence hierarchy, has been fiercely criticized. Yet studies that examine how Evidence is classified in EBM practice are rare. This article presents an observational study of the nature of Evidence and Evidence-Based Medicine as understood and performed in practice. It does this by examining how an absence of Evidence is defined and managed in Evidence-Based Guideline development. The EBM label does not denote the quantity or quality of evidence found, but the specific management of the absence of evidence, requiring a transparently reported process of evidence searching, selection and presentation. I propose the term ‘Evidence Searched Guidelines’ to better capture this specific way of ‘being’ EBM. Moreover, what counts as Evidence depends not just on the Evidence hierarchy, but requires agreement between the members of each guideline development group who mobilize a range of ‘other’ knowledges, such as biological principles and knowledge of the clinic. In addition, I distinguish four non-Evidentiary justifications that are relied upon in the formulation of recommendations (literature, qualified opinions, ethical principles, and practice standards). These are not always secondary to Evidence but may be positioned outside the hierarchy, allowing them to trump Evidence. The legitimacy of Evidence-Based Medicine relies neither on experts nor numbers, but on distinct procedures for handling (non-)Evidence, reflecting its ‘regulatory objectivity’. Finally, the notion of transparency is central for understanding how Evidence-Based Medicine regulates, and is regulated within, contemporary biomedicine.

Uncertainty and the Development of Evidence-Based Guidelines

“…It is the work of classifying knowledge and giving value to this knowledge. This signification of knowledge is what happens in guideline collectives (Knaapen 2013). A multidisciplinary group of actors is involved in establishing the content of the guideline, supported by methodologists experienced in selecting evidence and writing guideline texts.…”

“…Knaapen speaks of evidence-searched guidelines, as she shows how the essence of guideline development is to deal with absences of evidence (Knaapen 2013). In accepting uncertainty, the credibility of a guideline is ensured.…”

“…Knaapen argues that the core struggle of guideline development groups is to find ways to deal with the absence of knowledge. A central question that needs answering is what counts as evidence and what does not (Knaapen 2013). This discussion is the core of valuation work that emphasises signification (Kjellberg and Mallard 2013).…”

“…The "evidence-based" label gives the impression that evidence makes guidelines credible. However, as Knaapen argues, evidence-based medicine is more often about how to deal with the absence of evidence (Knaapen 2013). When asking guideline developers what "evidence-based" means, they answered that it deals congruently with working systematically and transparently:…”

Clinical Trials and the Drive to Material Standardisation

“…While the standardisation of clinical guidelines has been well analysed in this respect (Cambrosio et al, 2006;Castel, 2009;Knaapen, 2013;Knaapen et al, 2010), a feature of multi-centre clinical trials that has been relatively neglected is the standardisation of material settings. Perhaps because of their mundanity these have received little or no attention in the clinical trials literature and limited analysis in social studies of science.…”