Question

Epidemiology & relating health sciences.

What changes in existing policies and programs at the state and national level could make a sustainable impact on health equity?

Answer 1

Epidemiology is the method used to find the causes of health outcomes and diseases in populations. In epidemiology, the patient is the community and individuals are viewed collectively. By definition, epidemiology is the study (scientific, systematic, and data-driven) of the distribution (frequency, pattern) and determinants (causes, risk factors) of health-related states and events (not just diseases) in specified populations (neighborhood, school, city, state, country, global). It is also the application of this study to the control of health problems.
Health inequalities are disparities in health, reflecting either differences in access to a range of promotional, preventive, curative, or palliative health services or differences in outcomes including disability, morbidity, and mortality spanning physical, mental, and social health. The causes of inequalities in health are dynamic and reflect multiple determinants. Health inequities, however, are differences in health that are judged to be avoidable, unfair, and unjust. Health inequities are often revealed through systematic patterns or gradients in access or outcomes across populations with different levels of underlying social advantage or disadvantage—that is, wealth, power, prestige, or other markers of social stratification.

Numerous reviews across low-, middle-, and high-income countries continue to document that health inequalities are related not only to biological or genetic factors, but also to social factors that are amenable to policy and are potentially avoidable given cross-group or cross-population comparisons. Studies most often document differential access to health services based on an individual's socioeconomic position or place of residence, rather than on need, although other approaches exist. The place in the social hierarchy that individuals and groups occupy, combined with the epidemiological environment, then determines exposure and vulnerability to health-enhancing or health-damaging conditions in daily life (e.g., where people are born, grow, live, work, and age). The underlying causes are complex, often reflecting systematic social, political, historical, economic, and environmental factors that also interface with biological factors. The term “social determinants” is often used as shorthand for all of these factors and is relevant to communicable and non-communicable conditions alike. An added complexity is that negative or positive impacts of social determinants of health (SDH) can be accumulated during a lifetime, alter health trajectories across the life course, and be transferred across generations.

Moreover, labeling an inequality as an inequity also reflects a value judgment. This labeling is sometimes made explicit by deliberating on facts, clarifying underlying values, and designing remedial actions. Often, however, there is no process to discuss and debate what is observed, either because there is limited information or a narrow range of perspectives required for meaningful deliberations. The result is often inaction, with inequalities (and inequities) stagnating or getting worse. Values that are held by individuals, interested groups, experts, or policy makers, and the balancing of priorities, determine to what extent an objective epidemiologic fact is avoidable, unfair, and unjust and if anything will be done to address the root cause or even the symptoms. Values also shape who has the responsibility to act and the type of response that is undertaken.

Values can be enshrined in international norms. Two important documents set out rights for attaining the best average level of health and the smallest feasible differences among individuals and groups within countries and around the world: the Constitution of the World Health Organization (WHO) and the Universal Declaration of Human Rights. Both documents share principles of nondiscrimination and equal opportunity, outline the right to health, link health outcomes with SDH and other social goals that enhance population well-being, and address responsibilities of duty-bearers, primarily member states (e.g., governments) and those who act on their behalf, such as intergovernmental organizations.

Incorporating these principles and rights into the frameworks and practice of public health is possible. Moreover, public health professionals from around the world put equal weight on achieving improvements in overall health (i.e., goodness) and the distribution of health (i.e., fairness) as a way to measure health systems' performance. Improving fairness includes documenting health inequalities, identifying inequities, advocating for action, and ensuring that action is guided by evidence and ethics. Many contribute to this effort. As part of the work contributing to the WHO Commission on Social Determinants of Health (hereafter, the Commission), WHO documented—through new models and available data from demographic and health surveys, or equivalent surveys—that at least 25% of health inequalities (within-country differences) are due to a lack of access to effective health services. These health services often include essential services as recommended by WHO or national policies, including access to essential medicines or antenatal care visits. This percentage increases when adding in other basic public health interventions, such as access to safe water or sanitation. Additional SDH contribute to about another 50% of the total health inequalities documented, suggesting that, depending upon the process or outcome of interest, about 75% of health inequalities could be considered unfair and potentially avoidable, thus labeled as health inequities.

The evidence on the existence of health inequities is overwhelming and beyond the scope of this article. Many argue that it is reasonable to give priority to addressing health inequities—pointing out that cross-group and cross-population evidence documents what is potentially avoidable—whether as a gradient across an entire population, as a comparison between the worst-off and best-off groups in a population, or comparisons across populations. Even if different groups draw the line between inequalities and inequities at different points, the questions policy makers, practitioners, and interested groups ask are, “What can be done to reduce unfair health disparities?” and “How will we know if we succeed?” In fact, the stated goal of the Commission was to leverage policy change by turning existing public health knowledge into actionable policy agendas.

Building on the work of others, the Commission adopted a conceptual framework to illustrate broader determinants of health and the causal pathways to the distribution of health. This model illustrates the pathways by which SDH affect both health outcomes and distribution, makes explicit the linkages among different types of health determinants, and explains the ways social determinants contribute to health inequities among different groups in society given the increasing evidence of significant social stratification in health status. This conceptual framework served as the departure point on how to operationalize or make concrete monitoring and assessment, with the initial purpose of identifying pathways to different health or illness outcomes, and to distinguish between the causes of health improvement and the causes of health inequities.