Effectiveness of Health Impact Assessments: A Synthesis of Data From Five Impact Evaluation Reports

Since the 1990s, the use of health impact assessments (HIAs) has grown for considering the potential health impacts of proposed policies, plans, programs, and projects in various sectors. Evaluation of HIA impacts is needed for understanding the value of HIAs, improving the methods involved in HIAs, and potentially expanding their application. Impact evaluations examine whether HIAs affect decisions and lead to other effects.

I reviewed HIA impact evaluations identified by literature review and professional networking. I abstracted and synthesized data on key findings, success factors, and challenges from 5 large evaluations conducted in the United States, Europe, Australia, and New Zealand and published from 2006 through 2015. These studies analyzed impacts of approximately 200 individual HIAs.

Major impacts of HIAs were directly influencing some decisions, improving collaboration among stakeholders, increasing awareness of health issues among decision makers, and giving community members a stronger voice in local decisions. Factors that contributed to successful HIAs included engaging stakeholders, timeliness, policy and systems support for conducting HIAs, having people with appropriate skills on the HIA team, obtaining the support of decision makers, and providing clearly articulated, feasible recommendations. Challenges that may have reduced HIA success were poor timeliness, underestimation of time and resources needed, difficulty in accessing relevant data, use of jargon in HIA reports, difficulty in involving decision makers in the HIA process, and absence of a requirement to conduct HIAs.

HIAs can be useful to promote health and mitigate adverse impacts of decisions made outside of the health sector. Stakeholder interactions and community engagement may be as important as direct impacts of HIAs. Multiple factors are required for HIA success. Further work could strengthen the role of HIAs in promoting equity, examine HIA impacts in specific sectors, and document the role of HIAs in a "health in all policies" approach.