12.7 The Role of Epidemiology in Scientific Decision-Making and Policy Development

Epidemiology: The Foundation of Scientific Decision-Making

Epidemiology is at the foundation of scientific decision-making in health care and public health. Recall that epidemiology is the scientific study of the distribution and determinants of diseases and health outcomes in populations. Epidemiology aims to develop methods of controlling health problems, limit the consequences of illness, and maximize health. It is a broad definition with major implications for scientific decision-making. Health care clients, professionals, and public health practitioners, including nurses, base their health care decision-making and health education on sound epidemiological studies. These studies form the basis for the education that health care professionals provide at all levels. For example, epidemiological studies have demonstrated an association between screening for certain diseases and overall decreased morbidity and mortality. Other epidemiological studies have shown that decreased saturated fat intake and increased exercise are associated with better cardiovascular health.

Epidemiology: The Basis for Policy Development

Public health policy is based on evidence, and evidence can be garnered through well-designed epidemiological studies. Undergirding the development of policies that positively affect health outcomes of populations is one of the key roles of epidemiology.

Findings from epidemiological studies affect population health through a primary and secondary prevention lens and as a way to control disease. As mentioned, epidemiology is defined as the scientific study of the distribution and determinants of diseases and health outcomes in populations to increase understanding of disease and disease determinants to improve health outcomes. These are the intentional and practical applications of the study of epidemiology. They are investigations originated to address current and evolving health challenges with direct applications to public health through formulating and evaluating public policy. Developing public policy is, in fact, considered integral to the practice of epidemiology. John Snow’s examination of the cholera outbreaks in London is a classic example of this direct application for public policy. His removal of the handle from the Broad Street pump demonstrates the policy implications of his research findings. He was able to clearly document his findings, build trusting relationships within the London community and with lawmakers, and effectively affect health policy.

A contemporary example of the role of epidemiology in policy development is the history of youth tobacco control in the United States, using epidemiology to drive change and create a positive difference in health outcomes. By the 1960s, smoking had been linked to poor health outcomes such as lung cancer and other respiratory diseases, and great strides throughout the 1970s through the 1980s resulted in a dramatic decrease in adult smoking habits but did not impact youth smoking rates (Aldrich et al., 2015). In 1994, to address this issue based on descriptive and analytic epidemiological studies, the Surgeon General’s report recommended a paradigm shift in thinking about youth smoking. It shifted the focus from individuals, historically the target of youth smoking prevention programs, to populations and communities. This was accomplished through policy, and the American Stop Smoking Intervention Study for Cancer Prevention (ASSIST) exemplified this paradigm shift. The ASSIST program, with funding from the National Cancer Institute, many state health departments, and the American Cancer Society, changed economic, social, and cultural environmental factors in the states with participating health departments to discourage youth from smoking, motivated by epidemiologic evidence that secondhand smoke was dangerous (Aldrich et al., 2015). By reframing the issue as a societal concern over an individual problem, the community approach had a wider reach and could integrate tobacco-free norms into community institutions. ASSIST focused on four policy areas:

1. Elimination of tobacco smoke in public places
2. Decreased advertising and promotion of tobacco products
3. Decreased youth access to tobacco
4. Increased taxes on tobacco

By the time ASSIST ended in 1999, there were small but statistically significant reductions at the population level in smoking prevalence among adults compared with non-ASSIST states, and this decrease has continued. In 2021, 11.5 percent of adults (18 years and older) in the United States currently smoked cigarettes, a major decline from 20.9 percent of the population in 2005, a population health victory (CDC, 2023).

Intersection of Epidemiology and the 10 Essential Public Health Services

As introduced in Foundations of Public/Community Health, the 10 Essential Public Health Services (EPHS) are the public health activities necessary to ensure healthy communities. This framework was developed under the auspices of the CDC and the National Institutes of Health (NIH). Originally released in 1994, it was updated in 2020 to better align with contemporary community and public health practice. The goal of the EPHS is to achieve equity by promoting policies, systems, and community conditions that facilitate optimal health for everyone. This is accomplished by removing systemic and structural barriers that have resulted in health inequities (CDC, 2022a).

Epidemiology supports the 10 Essential Public Health Services in the following ways (CDC, 2022a):

Investigation and Monitoring

1. Assesses and monitors population health status (factors that influence health as well as community needs and assets) by
   • using vital statistics to track population changes in natality and mortality, and
   • using disease statistics to trend rates of communicable and noncommunicable diseases in the community.
2. Investigates, diagnoses, and addresses health problems and hazards affecting the population by
   • providing population health data to track diseases,
   • investigating unusual disease activity, and
   • launching epidemiologic investigations.

Policy Development

3. Communicates effectively to inform and educate people about health, factors that influence it, and how to improve it by
   • developing and distributing appropriate health information and resources,
   • using a variety of communication methods including social media, mass media, and peer networks,
   • developing and using culturally and linguistically appropriate information, and
   • engaging in two-way communication to build trust.
4. Strengthens, supports, and mobilizes communities and partnerships to improve health by
   • facilitating partnerships in the community that affect health,
   • building relationships with diverse groups within a community that reflect the population, and
   • supporting existing community partnerships with public health expertise.
5. Creates, champions, and implements policies, plans, and laws that impact health by
   • developing policies that improve public health and strengthen communities,
   • developing and implementing health improvement strategies,
   • providing input into policies and laws to ensure that health impact is reflected,
   • examining and improving existing policies and laws to correct past wrongs, and
   • ensuring that policies and laws are equitable for all to achieve health.
6. Uses legal and regulatory actions designed to improve and protect the public’s health by
   • ensuring that laws are equitably implemented,
   • conducting enforcement of sanitation with food preparation, safe drinking water, and hazardous exposures,
   • monitoring the quality of health care–related services, and
   • licensing of the health care workforce.

Assurance

7. Ensures an effective system with equitable access to the individual services and care needed to be healthy by
   • connecting populations to needed services,
   • ensuring access to cost-effective and quality health and social services,
   • sharing data across partnerships to foster health and well-being, and
   • contributing to the development of a safe and competent health care workforce.
8. Builds and supports a diverse and skilled public health workforce by
   • providing education and training,
   • building partnerships with schools and training programs,
   • promoting a culture of learning in public health, and
   • incorporating public health principles in non–public health curricula.
9. Improves and innovates public health functions through ongoing evaluation, research, and continuous quality improvement by
   • linking public health research with practice,
   • using research to inform decision-making, and
   • contributing to the base of evidence in public health.
10. Builds and maintains a strong organizational infrastructure for public health by
    • ensuring that resources are allocated equitably,
    • exhibiting ethical and effective decision-making, and
    • being accountable and inclusive with all community partners.

This chapter has highlighted the important role epidemiology plays in public health, particularly in disease control and prevention. Epidemiology is the scientific underpinning of all public health efforts, from prevention of disease, illness, accidents, and injuries to early identification of chronic diseases via screening to management of disease outbreaks and complications from disease. The mission of public health is to ensure the conditions in which people can be healthy, and epidemiology provides the evidence for scientific decision-making and education efforts to fulfill that mission. Nurses must have a basic understanding of epidemiological principles to speak knowledgeably about the evidence underlying recommended public health interventions. Community and public health nurses fulfill the mission of public health by participating in the 10 Essential Public Health Services within the community and population in which they serve.