9a. Evidence-Informed Public Health  

The last module introduced you to the most widely used frameworks or models to guide the planning of population health interventions. This week’s module provides a more detailed focus on a key step embedded in these frameworks: the appraisal of evidence in order to prioritize and select the most effective mix of population health interventions.

While decisions regarding the implementation of population health interventions must be based on best practices, the models applied to translate evidence into practice are often viewed as time-consuming and difficult to comprehend.1 Moreover, as public health practitioners, you will have to balance decisions about evidence with other factors such as timelines, budget and staffing constraints, and social and political conditions in the community that pose challenges to the adoption of evidence-based practices.

The content of this week’s module introduces you to some key tools and resources for the timely appraisal of population health evidence as well as some key considerations regarding the application of this evidence to population health settings.

Key Concepts and Resources

Evidence-informed public health (EIPH) has its origins in evidence-based medicine (EBM), defined by Dr. David Sackett as “the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.”2 The concept of EBM subsequently expanded to encompass evidence-based public health (EBPH), which is defined as “the process of integrating science-based interventions with community preferences to improve the health of populations.”3 Evidence-informed public health, a concept developed by the National Collaborating Centre for Methods and Tools at McMaster University, incorporates the principles of EBM and EBPH, while recognizing the myriad of factors beyond evidence that guide decision-making.1

EIPH proceeds over seven stages (see Figure 1). This section focuses on stages 2-4 by reviewing the key sources and considerations for searching, appraising, and synthesizing population health evidence for effective intervention planning. 

Figure 1. Stages in EIPH
 Stage in EIPH Description
1. Define Clearly define the question or problem 
2. Search Efficiently search for research evidence 
3. Appraise Critically and efficiently appriase the research sources 
4. Synthesize Interpret/form recommendations for practice based on the literature found 
5. Adapt Adapt the information to a local context 
6. Implement Decide whether (and plan how) to impleent the adapted evidence into practice or policy 
7. Evaluate Evaluate the effectiveness of implementation efforts 

 

Divided circle showing the stages in evidence-informed public health: Define, Search, Appraise, Synthesize, Adapt, Implement, and Evaluate

Figure 1. Stages in Evidence-Informed Public Health

Systematic Reviews: A Useful Source for Synthesized Population Health Evidence

One of the key challenges faced by public health decision makers is keeping up with the sheer volume of published research. As of 2014, over 2.5 million peer reviewed papers were published by over 28 000 scientific journals.4 Fortunately, systematic reviews assimilate large bodies of evidence for a range of population health interventions. 

Stacks and stacks of papers

Systematic reviews select a set of studies addressing a particular research question and evaluate the results of these studies to reach conclusions about an entire field of research (e.g., effective methods for preventing cycling-related injuries). Unlike other approaches to reviewing literature, systematic reviews employ a standardized approach for identifying relevant studies.5 The following table provides further elaboration on the differences between a systematic review and less rigorous literature reviews.

Table 1: Traditional versus Systematic Literature Reviews
  Traditional Literature ReviewSystematic Review 
The review question/topic Topics may be broad in scope; the goal of the review may be to place one's own research within the existing body of knowledge, or to gather information that supports a particular viewpoint.  Starts with a well-defined research question to be answered by the review. Reviews are conducted with the aim of finding all existing evidence in an unbiased, transparent and reproducible way. 
Searching for studies Searches may be ad hoc, and based on what the author is already familiar with. Searches are not exhaustive or fully comprehensive.  Attempts are made to find all existing published and unpublished literature on the research question. The process is well-documented and reported. 
Study selection Often lack clear reasons for why studies were included or excluded from the review.  Reasons for including or excluding studies are explicit and informed by the research question. 
Assessing the quality of included studies Often do not consider study quality or potential biases in study design.  Systematically assess risk of bias or individual studies and overal quality of the evidence, including sources of heterogeneity between study results. 
Synthesis of existing research Conclusions are more qualititative and may not be based on study quality.  Base conclusion on quality of the study, and provide recommendations for practice or to address knowledge gaps. 

Brown University Library (2018, February 26). Systematic and Literature Reviews. Retrieved from http://libguides.brown.edu/Reviews/types

Key Sources of Systematic Reviews for Population Health Interventions

Sources of systematic reviews that are especially helpful for public health practitioners include

  • The Cochrane Library: Founded in 1993, the Cochrane Database of Systemic reviews is a key resource for systematic reviews of health interventions, including preventive interventions and health policies.
  • The Campbell Collaboration Online Library: The Campbell Database is similar to the Cochrane Database, but is focused on policy interventions related to key health determinants such as nutrition, education, and social welfare.
  • The Community Guide: In 1996, the US Task Force on Community Preventive Services began to synthesize scientific information about the effectiveness of health promotion and disease prevention interventions for a range of topics, including cancer, diabetes, mental health, health equity, physical activity, violence, and workplace health. To date, the Task Force has produced a range of evidence-informed “best practice” reports on population health interventions that can be accessed through the community guide website.
  • The Canadian Best Practices Portal: Although it is not a compendium of systematic reviews, the Canadian Best Practices Portal, which is maintained by the Public Health Agency of Canada (PHAC), provides a range of helpful publications and resources on evidence-informed population heath interventions. 

References

  1. Ciliska, D., Thomas, H., & Buffett, C. (2008). A compendium of critical appraisal tools for public health practice. Hamilton, ON: National Collaborating Centre for Methods and Tools. Retrieved from: http://www.nccmt.ca/uploads/media/media/0001/01/b331668f85bc6357f262944f0aca38c14c89c5a4.pdf
  2. Sackett, D.L., Rosenberg, W.M., Gray, J.M., Haynes, R.B., & Richardson, W.S. (1996). Evidence based medicine: what it is and what it isn't. British Medical Journal 312, 71–72.
  3. Kohatsu, N.D., Robinson, J.G., & Torner, J.C. (2004). Evidence-based public health: an evolving concept. American Journal of Preventive Medicine, 27(5), 417–421.
  4. Boon, S. (2016). 21st century science overload. Canadian Science Publishing–The CSP Blog. Retrieved from: http://www.cdnsciencepub.com/blog/21st-century-science-overload.aspx
  5. Hulley, S. B., Cummings, S. R., Browner, W. S., Grady, D. G., & Newman, T. B. (2013). Designing clinical research (4th ed.). Philadelphia: Walters Kluwer-Lippincott, Williams and Wilkins.