1 Introduction

Health disparities have only recently come to the forefront in Japan, despite the topic being of interest in foreign countries since the 1980s. With increasing awareness comes corresponding interest in measures to address health disparities. One potential solution is the implementation of a health impact assessment (HIA).

An HIA is a series of methodologies aimed at predicting the potential impact of a newly proposed policy on health. The strategy optimizes policies for promoting health benefits while minimizing conditions that will have negative effects. Today, HIAs are widely used as a tool to prepare national or local policies related to employment, housing, traffic, education, and urban development, particularly in Europe [1]. They can be categorized into three types, focusing on environmental impact, social effects, and health inequity.

In Asia, HIAs are also becoming increasingly popular. Implementation of HIAs in Japan is similar to that for environmental impact assessments, which are required before large-scale development. However, differences in HIA types can cause problems, because standardized protocols for one type may not apply in all cases. Here, we focus on HIAs targeting health disparities.

2 Health Disparities and Health Inequity

There is no general consensus regarding Japanese terms such as health disparities, disparities of health, health inequity, and unfairness. Thus, it is necessary to clarify the context in which each term is used.

Health disparities refers to differential between-group distribution of good health and factors related to health. For example, older people and young people differ in disease prevalence, while geographical regions differ in mortality rates. The source of health disparities may be from variation in biological (genetics) or demographic (sex and age) factors between groups.

Because intervention to correct biological factors may be impossible or unethical, health disparities caused by such reasons cannot be completely avoided. However, in many cases, variation in physical environment or socioeconomic status can also generate between-group health differences. While such environmental variation results from factors that cannot be easily corrected through personal effort, intervention targeting the environment is more acceptable. In addition, health disparities derived from the socioeconomic situation are considered unethical. Such instances can thus be associated with health inequity.

Health inequity refers to health disparities caused by social disadvantage, resulting in more moral and ethical judgement [4]. The World Health Organization (WHO) advocates “health for all,” a concept that maintains all people have equal right to health.

In Japan, the term “health disparities” now directly implies health inequity and all of the associated ethical issues. Nevertheless, the distinction between health disparities and inequity should be preserved whenever possible.

3 Domestic and Overseas Health Disparities

Four comprehensive reviews regarding health disparities worldwide have been conducted, with the first being the Black Report [2], followed by the Acheson Report [3]. Then, in 2008, the WHO-established Commission on Social Determinants of Health (CSDH) presented “Closing the gap in a generation: health equity through action on the social determinants of health” [4]. Two years later, the Marmot Review was published [5]. Based on these reviews, several countries (e.g., the Netherlands and Sweden) have presented comprehensive plans of national strategies to correct health disparities [6, 7].

In Japan, health disparity is closely associated with educational background, income, and employment [8,9,10,11,12,13,14,15].

4 Applying HIAs to Correct Health Disparities

Health equity involves equalizing access to opportunities that improve health [16]. A report by the CSDH emphasized the need to treat these issues under the framework of social justice.

Most of the reports have suggested HIAs as a means of correcting health disparities [3,4,5,6, 17]. A common understanding of these strategies is that interventions with potential to reduce health inequities are mainly in areas other than healthcare. Therefore, most issues related to the effects of socioeconomic status on health can only be resolved through implementing cross-sectional policies. These include regulations for income and housing, taxes on recreational drugs (cigarettes or alcohol), as well as improved labor regulation. In summary, health disparities cannot be mitigated unless HIAs cover relevant fields in addition to healthcare [3, 18].

The Acheson Report [3] lists HIAs at the top of its recommendations for decreasing health inequity. All health-associated policies use HIAs to assess potential impacts on health inequalities and then to reduce those inequalities as much as possible. Similarly, the CSDH report [7] indicated that an HIA should be implemented for all policies, and recommended a system for doing so at the national level.

5 What Is an HIA and Health Equity Impact Assessment (HEqIA)?

The current definitions for HIA come from the WHO and the International Association for Impact Assessment (IAIA). The WHO Gothenburg Paper [19] defines an HIA as “a combination of procedures, methods, and tools by which a policy, a program, or a project may be judged as to its potential effects on health of a population and the distribution of effects within the population.” Notably, this early-stage definition [20] did not include any mention of health disparities. However, the Gothenburg Paper confirmed that assessing health disparities was an indispensable function of an HIA, so such language was explicitly included in revised definitions.

Both the CSDH report [4] and the Marmot Review [5] used the term “Health Equity Impact Assessment” (HEqIA). Based on assessment from the International HIA Conference, HEqIA was essentially the same as an HIA, because the latter automatically includes a disparities assessment. Taken together, these reports indicate ongoing refinement of appropriate methods and evaluation of HIA performance focusing on health disparities.

6 Social Environment Model for Health

In general, HIAs are based on the social environment model, which states that social structure and socioeconomic factors directly and indirectly influence the health of an individual or population [16]. These social health determinants have been recently validated in the field of public health and are now recognized widely. Social health determinants are associated with many fields. The Ottawa Charter for Health Promotion, for example, cited the following variables as preconditions of health: peace, housing, education, food, income, environmental stability, sustainable resources, social justice, and fairness. Assessment of policies using an HIA would thus account for the complex variation in social environments.

7 “Health in All Policies” and Governance

The Healthy Public Policy in the Ottawa Charter suggests that we can optimize the impact of “non-health policies” to improve societal health, by requiring the inclusion of health-promotion measures at every policy opportunity. In other words, policies other than those related to healthcare should be considered under the jurisdiction of HIAs, as mentioned earlier. However, in many cases, we do not have sufficient infrastructure to determine the relation with health when planning for non-health policies.

To address this absent infrastructure, the Ottawa Charter has refined the concept of non-health-policy inclusion, generating the “Health in All Policies” initiative. This aims to facilitate the preparation of policies in all fields, including education, real estate, development, and employment, to better consider their relative impact on health. Specifically, health-conscious governance should form well-regulated policies based on scientific knowledge and the social environment model of health [17]. HIAs are valuable tools for realizing the “Health in All Policies” initiative.

8 How Does an HIA Evaluate Disparities?

First, differential impact of policies or projects on social strata (various populations with distinct attributes) must be assessed. This necessity is based on an awareness that the health effects of a policy vary according to a given population’s characteristics. In particular, socially disadvantaged populations are especially vulnerable to adverse effects. The following points are typically considered when determining whether a policy is unequal [21, 22]:

  • Socially disadvantaged populations are more likely to be affected.

  • Does a newly proposed policy promote health disparity?

  • Will a new policy increase disparity in a certain population?

  • What is the distribution of and exposure to specific health determinants and risk factors or changes in accessibility to services?

9 Prospective Effects of Including Health Disparities in an HIA

9.1 Influence on the Decision-Making Process

In an HIA, merits and demerits of proposed policies are assessed from standpoints of health disparities and fairness. The goal of an HIA is to obtain the best evidence possible, collecting and analyzing data regarding the potential influence of proposed policies on health disparities. Thus, various protocols can be used, including both quantitative and qualitative evaluations, such as a participatory approach.

9.2 Promoting a Better Understanding of Associations Between Policies and Health

By demonstrating the association between policies and health disparities, an HIA allows leaders to determine how their proposals affect public health. Findings on social health determinants using HIAs allow for beneficial revisions to governmental strategies that can address health disparities effectively.

9.3 Participatory Approaches and Empowerment

A participatory approach is often used in HIAs. Both the findings and the process of an HIA have important uses. One particular advantage of a participatory approach is that populations potentially at risk of negative health effects can undergo detailed health-disparity assessments through their involvement in an HIA. Furthermore, such an approach allows subjects to voice their opinion on health. The immediate disclosure of this information increases population self-effectiveness. In short, a participatory approach promotes health through increasing the opportunity for individuals to participate in decision making regarding their lives.

10 Future Directions

Numerous fields in Japan can benefit from HIAs. In particular, we recommend the implementation of “Health in All Policies,” with the goal of eliminating health disparities in the future. To do so successfully, we first must understand the social environment model in all departments responsible for policy making. Next, we should prepare a system that can effectively implement HIAs and collect the resultant data. We should also aim to have interdisciplinary cooperation and discussion regarding direct and indirect health effects. Finally, specialists responsible for HIAs must be trained and developed.