'More research needed': plugging gaps in the evidence base on health inequalities

Policymakers and public health researchers have demanded better evidence of the effects of interventions on public health and health inequalities and have pointed to the relative absence of rigorous outcome evaluations in this area. While most of these commentators agree that health inequalities are a problem, the means of tackling them often seems to rest on poor evidential foundations. This is no longer surprising, as the problem has been well-documented and the solution probably seems clear: if there is not enough evidence, then obviously we need more; and if the evidence is ‘weak’, well, then, it just needs to be ‘stronger’ in future. The funding environment in the UK, at least, is supportive of the production of this new, stronger evidence, with several new funding initiatives which are aiming to foster the production of new evaluations of public health interventions. However, it might be useful to consider further what ‘more evidence’ might look like (that is, what sort of evidence is needed) and how might it be ‘stronger’ than in the past and also to consider what additional challenges collecting this new evidence might bring. It is clear that evidence on the effectiveness and cost-effectiveness of public health interventions is often missing. Sometimes this is because policies are insufficiently subjected to outcome evaluation, perhaps because it is assumed that they are mostly beneficial and any positive outcomes can be taken as read. Randomized controlled trials of policies are particularly uncommon and there are a variety of real and perceived barriers to trials. This means that the public are frequently ‘enrolled’ in real-life policy ‘experiments’ without giving their explicit consent,or indeed without any real prospect of anyone learning anything substantial about the effects of those interventions. Although the experimental nature of most policies is generally unacknowledged, this is not always the …