Should action take priority over further research on public health?

Politics, evidence, and ambiguity

A focus on “insufficient evidence” often betrays a simplistic view of policy making, that evidence is used merely to reduce uncertainty. Politics is actually about using evidence to reduce ambiguity. Evidence is important, but policy change requires a powerful story and the ability to exploit windows of opportunity.2 Effective political actors use evidence to draw attention to urgent problems, encourage policy makers to understand them primarily as epidemics, and generate demand for evidence based public health solutions—for example, the recent smoke-free legislation and levy on sugary drinks.

A delayed response to evidence can be damaging. For example, a cumulative meta-analysis published in 1972 provided ample evidence that thrombolysis reduced deaths from heart attack by about 25%.3 However, repeated failure to consider this substantial evidence, compounded by medical conservatism, meant that thrombolysis was not widely used until 20 years later. Many patients were thus denied effective treatment,4 likely resulting in about 50 000 avoidable deaths over two decades in the United States. Systematic reviews alone may not be …