Evaluating health impact assessment.

Health impact assessment (HIA) is a developing approach that assesses the health impacts of a proposal on a population, and produces a practical set of recommendations to inform the decision-making process of the proposal. The purpose is to influence decision makers to increase positive health impacts of a proposal and decrease negative impacts. Most work within the HIA field to date has focused on methodological development and actually carrying out HIAs. Little attention has been paid to the formal evaluation of the HIA approach and whether or not HIA works (if and how the HIA approach informs the decision-making process and, in particular, if it contributes to improving health and reducing inequalities). With the drive towards evidence-informed policy, HIA also needs to show whether it adds value to the decision-making process, given the significant resources often involved in carrying out an HIA. A suggested approach to evaluating HIAs is presented, as well as its relationship with monitoring, drawing on the significant public health evaluation literature that already exists. Methodologies appropriate for use, and examples of indicators suitable for HIA evaluation, are provided. We suggest that typical HIA evaluations should focus on the process of the HIA and the impact that it has on the decision-making process, rather than attempting to evaluate long-term health outcomes or whether predicted impacts actually occurred.