Despite an increasing body of research on the uptake and impact of research on policy, and encouragement for policymaking to be evidence-informed , research often struggles to identify a policy audience. The research-policy gap’ is the subject of much commentary and research activity [2, 3, 4]. Interventions to bridge this gap are the focus of recent systematic reviews [5, 6, 7]. To ensure these interventions are appropriately designed and effective, it is important that they address genuine barriers to research uptake, and utilise facilitators which are likely to affect research uptake.
It is now well recognized that policy is determined as much by the decision-making context (and other influences) as by research evidence [8, 9]. Policymakers’ perceptions form an important part of this story, but not the whole. Innvaer  aimed to review studies about the health sector, but the influence of the evidence-based policy movement is now recognized to be important across many policy areas. In the UK, with the creation of Clinical Commissioning Groups, Health and Well-Being Boards, and private providers moving into areas traditionally occupied by the NHS, a broader range of policymakers are becoming potential evidence-users’ than ever. Researchers need to take stock of what we know about evidence-based policy, what we don’t know, and what can be done to assist these users.
The last systematic review looking at policymakers’ perceptions about the barriers to, and facilitators of research use was Innvaer . The findings from this review were corroborated by later research [11, 12], but no systematic update has yet been undertaken. In addition to updating this review in the area of policymakers’ perceptions of barriers and facilitators to use of evidence in policy, we also wished to include perceptions from other stakeholder groups than policymakers, such as researchers, managers, and other research users. Furthermore, it may be possible to identify factors affecting research use without relying on the perceptions of research participants – for example, ethnographic studies may produce observational data about knowledge exchange. In addition, we acknowledge that interest in using evidence to inform policy has spread beyond the health sector. Therefore, we aimed to update Innvaer  to include studies identifying all barriers and facilitators of the use of evidence in all policy fields.