Background to the Montréal Declaration on the Synthesis of Evidence to Advance the 3 Rs

to fully implement the principles of humane science, including the unifying concept of the three Rs (Replacement, Reduction, and Refinement of animal use) (Russell and Burch, 1959), there is universal agreement that animals should only be used for scientific purposes when no Replacement alternative is available. Where animals continue to be used, it is both a scientific and ethical imperative to ensure that all animal studies are of relevance and quality. to achieve this objective, a thorough inventory and analysis of all previously performed studies relevant to the question at hand, not only as individual studies but also in relation to one another, is an important step prior to the use of an animal model in support of a particular research question. In other words, a synthesis of evidence is called for. Within medicine, synthesis of evidence (e.g., systematic reviews) is used in order to evaluate and synthesize the outcome of individual study results. For the purpose of the Montréal Declaration, which focuses on animal studies, synthesis of evidence is defined as the contextualization and integration of research findings of individual research studies within the larger body of knowledge on the topic. According to Grimshaw (2010), synthesis of evidence can take a variety of forms: for example, meta-analysis, outcomes from a consensus conference or expert panel, or a literature-based review. Whatever its form, however, a synthesis of evidence must be reproducible and transparent in its methods, using quantitative and/or qualitative methods1. The current paper reflects on the origins of synthesis of evidence for human medicine, then goes on to outline the importance of conducting similar processes for animal-based studies. Recommendations are given on the steps that should be followed to achieve systematic reviews for animal studies.