Submitted to the University of Hertfordshire in partial fulfilment of the requirements of the degree of Doctor of PhilosophyBackground: The last few decades have seen a growing emphasis on evidence-based decision making in health care. Systematic reviews synthesising and evaluating research have been a key component of this movement. However, there is concern that such syntheses do not have the expected impact on policy and practice and more work is needed to enable us to maximise their potential. The aim of this study was to increase understanding of the likely impacts of systematic reviews on policy and identify factors that might facilitate their influence.\ud
Methods: My own previously published work is integral to this study. I took ten systematic reviews on which I am an author and used established methods for the evaluation of research impact, including, bibliometrics and documentary review, to examine whether these reviews had influenced policy development. Data from these analyses were combined with an overview of the literature to identify factors that might increase impact.\ud
Results: The reviews had influenced the development of national and international policy, although much of the impact was at a ???micro??? level in the form of practice guidelines. There was considerable variation in the impact of the reviews. Reviews evaluating fluid resuscitation and road safety interventions showed the greatest evidence of impact and a review of qualitative studies on barriers to fall prevention the least. Differences might be explained by time since publication, type of question, importance to policy makers, the nature and strength of the evidence, the purpose of the review and the networks and strategies used for dissemination.\ud
Conclusions: Systematic reviewers should consider the desired impacts of their work and include appropriate strategies for increasing impact, these should be detailed in the review protocol. This might include specifying methods to address applicability to particular contexts, and devising active strategies for dissemination