“Since when has a single scientific study constituted ‘the truth’ about anything?”1

Scientists have known about biases in single observations for centuries.2 A wealth of empirical evidence amassed across many disciplines tells us that single studies can be biased, are often seriously methodologically flawed and highly time and context dependent, and have findings that are likely to be misinterpreted and misrepresented (sometimes by the authors themselves). Increasingly it is accepted that decisions should not be based on the findings from single primary studies but rather informed by actionable messages derived from synthesised evidence based on systematic reviews.3 4 5 Over the past decade there has been substantial public funding of synthesised evidence and guidance to support healthcare decision making. In the United Kingdom this investment has been described as NHS research and development’s most important contribution to the global science base.6

Despite this investment the evidence indicates that although the transfer of research knowledge is possible its success can be variable.7 8 There is now renewed interest and emphasis on the gaps between research and policy and practice, nationally9 10 and internationally.11 …