focus—such as ones that use a narrow definition of health and emphasize quantification—from HIAs that have a broader, holistic focus shaped by the social determinants of health (Kemm 2001). Others have proposed categorizing HIAs as participatory (emphasizing shared governance, public participation, and a focus on socioeconomic and environmental determinants), quantitative or analytic (concentrating on the methods and rigor of the analysis), or procedural (drawing on elements of the other two approaches but emphasizing the procedural steps required and often undertaken within a specified administrative or regulatory context) (Cole and Fielding 2007).
In practice, the categories are rarely used consistently, and a single HIA often encompasses a blend of various approaches to stakeholder engagement and participation, analytic methods, and interactions with the formal decision-making process. For example, desktop HIAs may consider indirect stakeholder input through review of public comments submitted outside the HIA process, comprehensive HIAs may have relatively little stakeholder engagement, and rapid-appraisal HIAs of smaller-scale proposals may involve collection of some new data to inform the analysis. The various categories of HIAs, although useful for describing distinct themes in the field, do not necessarily represent consistently distinct strains of practice. Instead, it appears that the specific methods and approaches used in a single HIA often evolve within the basic framework described above and develop as a pragmatic response to context. Influences on practice include the timeline, resources and skills available to the HIA team, the factors being considered and the data available for analysis, and the legal and regulatory context of the decision-making process. That description is consistent with the earlier characterizations of HIA as a combination of procedures, methods, and tools (WHO 1999; Quigley et al. 2006).
The committee notes that the diversity of approaches and decision contexts imposes challenges for determining the resources required for conducting an HIA. For example, although rapid HIAs are small-scale, low-cost investigations, comprehensive HIAs that require new primary data collection can take longer than a year to complete and require substantially more resources. Information on costs of HIAs would be valuable in determining whether an HIA can be undertaken with the resources available and could inform the screening process as described below. However, the committee notes that no published studies in the United States have attempted to quantify the costs of undertaking an HIA across a variety of settings. Such information would be useful for informing future implementation.
The committee proposes on the basis of its review the following adaptation of the current working definition of the International Association of Impact Assessment (Quigley et al. 2006) as a technical definition of HIA: