Dunja Dreesens

87 Chapter 5 Introduction The challenge of knowledge inclusion in guidelines Evidence-based guidelines whether national, regional or developed by specialty groups, must search for, and explicitly consider, evidence from sources other than conventional clinical trials and their quantitative data. This need for appraising and including knowledge from a wide variety of sources in guideline development is well recognised (47, 214, 215). Although evidence on statistical association – usually from randomised controlled trials (RCTs) – is commonly thought to be the dominant type of knowledge appraised and included, guideline developers frequently use a range of other types of knowledge including the views and experiences of those using and providing health services, understanding of how interventions work (e.g. from logic models or realist evaluations), and other information, such as aetiology and the context of care (see Text box 1). Text box 1: Types of knowledge TYPES OF KNOWLEDGE Defining knowledge is challenging as many ideas and theories about what knowledge entails exist. In this paper, we regard other types of knowledge as any knowledge that wouldnot be considereda systematic review or RCT. This would include, but not be limited to, a broad range of explicit understandings of knowledge such as knowledge from outbreak investigations, laboratory research, mathematical modelling, qualitative research, quality improvement processes and clinical audits but also tacit knowledge, practical knowledge and heuristics. These different types of knowledge are used and needed in many situations, for example, when evidence from RCTs is not available, impossible to obtain, contradictory or inappropriate. They can also be used in conjunction with knowledge from RCTs to provide context, to assess relevance and to understand bias. Furthermore, explicit (written or spoken) knowledge and the more intricate forms of knowledge like experiential and contextual knowledge can help guideline makers to take an approach consistent with the intentions of early evidence-based medicine (EBM) proponents: namely, that best evidence is not restricted to evidence from RCTs and meta-analyses alone (26). However, how to properly appraise (judge) and include (integrate) different kinds of knowledge remains unclear. Agreed methods are not yet available or are in the early stages of development and the need for and use of different kinds of knowledge is not always explicitly acknowledged, which affects the use of guidelines in practice (8, 216-218). International and cultural differences in guideline production practices may further impede developments in appraising and including a broader range of types of knowledge (see Text box 2).