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The Science and Practice of Applied Public Health

Plescia, Marcus, MD, MPH

Journal of Public Health Management and Practice: March/April 2019 - Volume 25 - Issue 2 - p 201–204
doi: 10.1097/PHH.0000000000000977
State of Public Health

Association of State and Territorial Health Officials, Arlington, Virginia.

Correspondence: Marcus Plescia, MD, MPH, Association of State and Territorial Health Officials, Arlington, VA 22202 (

The author declares no conflict of interest.

Over the last 2 decades considerable progress has been made in developing the evidence base for public health practice and learning how to best disseminate these approaches. Evidence-based practice has been embraced in many health-related disciplines and much can be learned from the experience in clinical medicine. While significant challenges and undesired practices remain, a well-developed culture and norm of evidence-based medical practice has been developed over the last 2 decades that has helped balance traditional reliance on clinical experience with evidence from clinical research. Evidence-based practice is now the core of medical training both in the classroom and at the bedside. As a result, medical practices have ready access to the scientific literature, previously widespread physician detailing by industry has been discredited and curtailed, and information systems like electronic health records have been tailored and improved to prompt evidence-based action and access to practice guidelines.

The practice of evidence-based public health faces challenges and opportunities relative to medical practice. Public health studies are inherently more difficult to design. They frequently rely on the interpretation of natural experiments and may involve multiple blended interventions within a community of diverse and often disparate groups. However, while they are challenging to study and evaluate, public health approaches also allow creativity that ultimately makes their application in community settings more relevant and productive.

Few professionals would dispute the importance of evidence-based practice. Significant improvements in public health can be credited to the successful implementation of scientifically driven interventions that have had significant population impact. To achieve state and national objectives for improved population health, more widespread adoption of evidence-based strategies is needed, paired with practice-based approaches to overcome common challenges and take effective interventions to scale. Public health agencies that support and provide technical assistance to public health providers can play a significant role in this transition. This commentary describes specific steps to help health departments be more fluent in the use of established evidence-based practices, access and understand interventions that are promising or emerging, and develop intervention packages that can be widely implemented.

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Established Evidence-Based Practice

Evidence-based public health has been defined as “the process of integrating science-based interventions with community preferences to improve the health of populations.”1 Key components of evidence-based public health include making decisions on the basis of the best available, peer-reviewed evidence, using data and information systems systematically, applying program-planning frameworks, engaging the community in decision making, conducting sound evaluations, and disseminating what is learned.2

There are several resources to help identify evidence-based practices that are easily available to public health practitioners. For example, the Agency for Healthcare Research and Quality supports the Guide to Clinical Preventive Services, which is maintained by a panel of independent scientists and experts.3 This guide sets the standard for many of the clinical public health interventions that the Affordable Care Act has mandated as reimbursable services. Its sibling is the Community Guide, supported by the Centers for Disease Control and Prevention (CDC), which also engages a panel of experts and identifies evidence-based interventions for population-based applications.4 The Community Guide is easily navigable; it has an active web interface with the practice community and publicizes new recommendations through national organizations, funders, and social media. However, the Community Guide does not currently have the same capacity to mandate reimbursable programs or services.

Other well-developed clinical evidence reviews like the Cochrane Library also provide evidence-based recommendations for clinical preventive services and some community-based interventions.5 Cancer Control Planet, CDC's HIV Prevention that Works, and the Office of Adolescent Health's Evidence-based Teen Pregnancy Prevention Programs are examples of several reputable sources of evidence-based practice for specific public health issues.6–8 These resources and others are all widely available to public health practitioners and should be their first step in promoting, developing, and designing community-based interventions.

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Accessing Evidence-Based Practice Literature

The Clinical Guide and resources that define evidence-based practice have limited capacity to provide exhaustive and timely review and categorization of all emerging public health science. In addition, some recommendations identify science that is promising but do not meet their exacting standards for evidence-based practice. As a result, the public health workforce still needs training and technical support to access and interpret basic information from the scientific literature. Funders, national organizations, and contractors can help create and support an environment of discipline, inquiry, and comfort interpreting scientific publications in state and local health departments. One of the greatest barriers to this environment, and to the overall push for evidence-based practice, is the relative lack of easy, timely, and affordable access to emerging and existing scientific findings in the medical and public health literature.

Gaining access to published studies in peer-reviewed journals can be tedious and frustrating for even the most determined public health practitioner. The general lack of access to digital library resources in state and local government agencies is a challenge that has received little attention in the literature on evidence-based public health. Because societal access to information is a necessity for an informed populace and healthy democracy, a national movement has emerged to promote free and open access to scientific findings and publications that has a significant following in academia and among the lay public. Proponents of Open Access argue, since most scientific research is publicly subsidized through federal agencies, it should be more accessible for public use.9 Better access to the scientific literature is imperative to support a culture of professionalism across public health and other science-based disciplines. However, at present only 28% of scholarly publications are in open access journals.10 The remainder are controlled by publishing companies that charge user fees to access published studies, a situation that is particularly challenging for public health practitioners operating with limited resources in increasingly frugal settings.

Given the limited access to scientific publications, health departments and supporting professional institutions pursue a variety of approaches to access the scientific literature. The CDC and a small number of state public health departments have established their own digital libraries with a comprehensive collection of scientific journals, but this entails a relatively expensive process of negotiating access with publishers, and generally requires curation. In fact, the Association of State and Territorial Health Officials (ASTHO), a national public health organization with 130 employees, recently received a cost estimate of $150 000 to contract through an intermediary to gain access to the top 50 publications used at the CDC.

Digital libraries at medical schools or large health sciences university programs are the most robust and comprehensive source of scientific publications, but their agreements with publishers limit access to their students and faculty. Health department staff with faculty positions in public health schools may have some access to these digital libraries, but sharing this access with colleagues is formally prohibited and cannot be adopted by a reputable agency as a policy or widespread practice.

Recently, the National Library of Medicine developed a program to allow state health departments to access a curated collection of scientific journal and other resources for a relatively modest fee of $30 000 to $60 000.11 The collection is not as robust as a health sciences library, but negotiating a process for interlibrary loans from a local library partner increases access to journals that are not in the collection and a modest budget can support purchase of others. Currently, about half the state health departments participate in this service. Unfortunately, the program is not currently available for national organizations that support and provide technical assistance to these public health agencies.

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Effective Public Health Interventions

Evidence-based approaches are only one aspect of successful public health interventions. Just as there is an “art and science” to the practice of medicine, there is also an art and science to the practice of public health. Public health interventions must be acceptable and embraced by their intended populations. To that end, engaging communities in research design and evaluation through approaches like community-based participatory research and community-oriented primary care provides valuable insight into cultural and historical perspectives, and builds trust that may ultimately allow greater and more equitable participation in community interventions. Other new approaches like Health Impact Assessments, which estimate the impact of a policy or intervention in non-health-related sectors, such as agriculture, transportation, and economic development, allow for close collaboration with external agencies.12 These collaborations may ultimately be needed to address broader social determinants and bring greater reach and impact to public health interventions.

While serving as the Director of the CDC, Tom Frieden outlined 6 components of an effective public health intervention that speak to both the art and science of public health practice.13

He described the need for a “technical package” that is based on a limited number of evidence-based interventions, but also emphasized projected impact and estimated cost, based in part on the size and characteristics of the population to be reached and relative burden of modifiable risk factors. These considerations are particularly important to assure that public health interventions can ultimately be taken to scale across multiple communities and settings to impact population health indicators. Today, CDC's 6 to 18 initiatives build on this concept by outlining 6 public health interventions that are evidence-based, but also have potential for widespread impact, have acceptable costs and resource mechanisms, and are politically feasible.14 It provides a useful matrix for public health leaders seeking to prioritize the use of limited resources.

Finally, political considerations must also be considered with any public health issue. Leaders often need to act on high-profile health issues when evidence is not available on effectiveness. At times political ideology may be contrary to what science recommends, such as for water fluoridation or needle exchange programs. To overcome this resistance, strategic partnerships and communication campaigns must be paired with evidence-based approaches to meet the public health needs of the country.

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Support for State and Territorial Public Health Departments

Public health organizations that support and provide technical assistance to state, territorial, tribal, and local public health departments, including national organizations, federal agencies like the CDC and HRSA, schools of public health and other university-based programs, and private contractors, all must take deliberate steps to develop subject matter experts and staunch advocates to create and support an environment of discipline, inquiry, and science in applied public health. Ultimately evidence-based practice must become the norm for all public health agencies through the widespread support of public health leaders. To achieve this, respected leaders and subject matter experts must be highly trained and articulate in the tenets of evidence-based public health.

In the early 1990s, Ross Brownson and his team at Washington University received funding from the CDC to develop and disseminate evidence-based practice in state public health departments.15 They helped define dissemination science, developed publications, and partnered with the National Association of Chronic Disease Directors to provide direct training to state chronic disease programs through “train the trainer” approaches. The third edition of their book Evidence-Based Public Health was published in 2018, and their course has had widespread participation from national and international audiences including the ASTHO, the national nonprofit organization that represents the public health agencies of the United States, the US territories and freely associated states, and the District of Columbia.16

ASTHO members, the chief health officials within their jurisdictions, are dedicated to formulating and influencing sound public health policy and ensuring excellence in public health practice. A central tenet of ASTHO's new strategic plan is to improve public health through capacity building, technical assistance, and thought leadership. Over the last year, the ASTHO has expanded its efforts to increase state health leader's competency in evidence-based public health and support their efforts to make this approach an institutional norm. The ASTHO is developing a “train the trainer” approach for staff to work more effectively with state and territorial public health leaders to expand the use of established and emerging evidence-based practices in a variety of federally and state-funded interventions. The ASTHO will also seek opportunities to highlight implementation science in the future work of state and territorial health departments to help tailor and expand the public health evidence base, adapt to change and encourage innovation.

Governmental public health leaders and the public health workforce require evidence to inform the application of effective public health approaches needed to improve population health within their jurisdictions. National public health organizations must work to establish institutional norms that aim to increase state and territorial public health workforce fluency in established evidence-based practices, increase access to and understanding of these interventions, and support the development of appropriate intervention packages. Better integrating the science and practice of applied public health will result in more effective and appropriate interventions taken to scale in states and communities across the nation.

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3. Agency for Healthcare Research and Quality. Guide to Clinical Preventive Services. US Preventive Services Task Force.
4. The Community Guide. Your online guide of what works to promote healthy communities. The Guide to Community Preventive Services (The Community Guide). Published December 1, 2016.
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7. Office of Adolescent Health. Teen Pregnancy Prevention Program (TPP). Published February 13, 2017.
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