Evidence for Healthy Cities: reflections on practice, method and theory.

The European Healthy Cities project can be characterized as a social movement that employs an extremely wide range of political, social and behavioural interventions for the development and sustenance of urban population health. At all of these levels, the movement is inspired by ideological, theoretical and evidence-based perspectives. The result of this stance is a dynamic, complex and diverse landscape of initiatives, plans, programmes and actions. In quantitative terms (the number of WHO designated cities and associated cities and communities through national networks), 'Healthy Cities' can be regarded as an extraordinary accomplishment and a credit for both WHO and cities in the movement. In qualitative terms, however, critics of the movement have maintained that little evidence on its success and effectiveness has been generated. This critique finds its foundations in the mere perceptions of evidence, the politics of science and urban governance, and perspectives on the preferred or professed utilities of evidence-based health notions. The article reviews the nature of evidence and its interface with politics and governance. Applying a conceptual framework combining insights from knowledge utilization theory, theoretical perspectives on (health) policy development, theory-based evaluations and planned intervention approaches, it demonstrates that, although the evidence is overwhelming, there are barriers to the implementation of such evidence that should be further addressed by 'Healthy Cities'.