Objective To review: the process of public health policy-making; variations in the extent of research evidence used; other influencing factors; and barriers to and facilitators of the use of research evidence.

Design Systematic review of empirical studies reporting data on policy-making in public health.

Data Sources Databases searched: MEDLINE, SCOPUS, PsychInfo, CINAHL, The Social Science Citation Index, The Science Citation Index, The Arts and Humanities Citation Index, Applied Social Sciences Index and Abstracts, Database of Reviews of Effects, Cochrane Database of Systematic Reviews, DoPHER, the Campbell Library, and the Cochrane Register of Controlled trials. Other sources: screening of organisational websites, contacting key informants and scrutinising the bibliographies of included studies.

Review methods Two reviewers independently assessed studies for inclusion; extracted data and assessed methodological quality using predesigned forms. Disagreements were resolved by consensus or by recourse to a third reviewer. Data were synthesised as a narrative review.

Results 1216 articles were retrieved. Following screening 18 studies were included: 13 qualitative studies, four surveys and one literature review. Participants included 1200 policy-makers, 72 researchers, and 174 people involved in both activities. Studies were set in a range of country and policy-making settings. Methodological quality was mixed. The process of policy-making varies widely between settings, and is viewed differently by key players. An extensive range of types of research evidence are used in policy-making. However, it has only an indirect impact and competes with many other influences. Barriers to the use of research evidence are well-described and include: policy-makers’ perceptions of research evidence; the gulf between researchers and policy-makers; the culture in which policy-makers work; competing influences on policy-making; and practical constraints. Ways of overcoming these barriers are less well known, and include: research targeted at the needs of policy-makers; research clearly highlighting key messages; and capacity building. There is almost no evidence on the role of research evidence in addressing health inequalities, a key aim of public health policy.

Conclusions Action is required by both policy-makers and researchers to address the barriers identified in this systematic review. There is an urgent need for evidence on the best approaches to incorporating research evidence in public health policy, particularly that considering the complex effects on health inequalities.