How do experts define relevance criteria when initiating Health Impact Assessments of national policies?

AIM: The aim of this article is to present how the Danish Disease Prevention Committee (DDPC) members and HIA-experts understand when HIA is "relevant", which in this context means when there is "presumed to be a direct and documented effect on the health and morbidity of citizens".
METHOD: DDPC members were interviewed face-to-face; HIA experts participated in an e-survey.
RESULTS: Six DDPC members were interviewed and 100 HIA-experts participated in a survey. The DDPC members consider direct as the link between determinants and the related risk factors. The HIA experts consider direct as the link between policy and the related risk factors. Both groups favour the use of scientific evidence according to the traditional biomedical evidence hierarchy but HIA-experts also judge that there is value in using evidence that can be considered weak such as local community knowledge.
CONCLUSIONS: It is clear that the DDPC recommendation gives rise to a discussion on differing perceptions of relevance. The same definition can be used for both direct and indirect effects depending on interpretation. Documented evidence for an effect is desirable in the form provided by the traditional biomedical evidence hierarchy but HIA-experts emphasises use of local knowledge. The primary criteria for initiating a HIA, is whether the outcome of the HIA is expected to be taken into account in the decision-making process. The second criteria, is how do decision-makers perceive or interpret a decision to be relevant for HIA. This has implications for how and whether HIA will be implemented in Denmark in the future.