About the Evidence Summaries

The Initiative

The HI-5 (“high-five”), or Health Impact in Five Years, Initiative is a tool that highlights non-clinical, community-wide interventions with a proven track record. Each intervention listed is associated with improved health within five years or less as well as reported cost effectiveness and/or cost savings over the lifetime of the population or earlier.

The Approach

State, tribal, local, and territorial agencies asked CDC to review and share the science on community-wide approaches to identify what works. We developed the HI-5 tool through a careful and methodical process. We first compiled a list of interventions with the highest evidence rating from the Community Guide (“Recommended”)^[1] and the Robert Wood Johnson Foundation-funded County Health Rankings and Roadmaps: What Works for Health (Scientifically Supported”).^[2]We then screened out duplicates and patient-focused, clinical interventions, leaving 125 community-wide interventions. This initial list of 125 community-wide interventions was then assessed against the inclusion criteria to identify those interventions that improved health within five years or less and reported cost effectiveness and/or cost savings over the lifetime of the population or earlier. We also excluded those with evidence of potential harm, insufficient evidence of impact, those that were considered a component of another intervention, and those that were program-level interventions implemented at smaller scales. We then consulted with subject matter experts from across CDC to identify additional community-wide interventions supported by systematic reviews.

The final list, using all of these criteria, includes 14 community-wide interventions. We then created evidence summaries that described the HI-5 interventions, the public health issues, the health and economic evidence of impact, and provided selected resources.

The Frameworks Used

CDC consulted two frameworks to help identify community-wide population-oriented interventions:

1. Three Buckets of Prevention Framework

The Three Buckets of Prevention framework categorizes interventions according to three discrete domains on a continuum of prevention from health care to public health.^[3] Buckets 1 and 2 are patient-oriented and focus on both traditional and innovative clinical prevention approaches. These clinical interventions may occur in a doctor’s office or in the community and provide services to individual patients. In contrast, Bucket 3 focuses on population-oriented interventions that are intended as community-wide measures to protect and improve the health of populations of people and the community as a whole. As such, these upstream interventions address the context that makes the healthy choice the easy choice and the social, economic, and environmental conditions and risk factors in which people live, learn, work, and play. The HI-5 Initiative focuses on community-wide population-oriented interventions that align to Bucket 3.

Using this framework as a guide for health system and community level transformation, CDC’s 6|18 Initiative addresses issues in Bucket 1 and Bucket 2, while HI-5 addresses issues in Bucket 3. Together, HI-5 and 6|18 provide public health, health care, and a diverse array of other sectors with evidence across the continuum of prevention and care.

2. Public Health Impact Pyramid

The public health impact pyramid is a framework for public action.^[4] It visually depicts the potential impact of different types of public health interventions. At the base of the pyramid are those interventions that have the greatest potential for impact on health because they reach entire populations of people at once and require less individual effort. These include interventions that address social and economic determinants of health. Moving towards the top of the pyramid are interventions that change the context to make healthy choices easier; clinical interventions that require limited contact but confer long-term protection; ongoing direct clinical care; and health education and counseling. The HI-5 Initiative maps directly to the two lowest tiers of public health pyramid with the greatest potential for impact. HI-5 interventions focus on addressing the social and economic determinants of health and changing the context to make the healthy choice the easy choice.

The HI-5 Evidence Summary Criteria

To be included in the HI-5 Initiative, the evidence for each health outcome had to include a systematic review, or at least 3 randomized control trials, or 3 quasi experimental studies with comparisons, or studies with direct evidence of impact, for example exposure to particulate matter. In addition, an intervention had to meet the following inclusion criteria:

Inclusion criteria applied to existing evidence	Definitions
Community-wide / population-oriented	Focus on whole populations or whole communities
Measurable Impact on Health	Has evidence of a positive impact on health within five years
Economic Data	Has evidence reporting cost effectiveness and/or cost savings over the lifetime of the population or earlier
Saturation	Has not yet been implemented in at least 85% of communities and/or states
Level of Impact	Evidence that intervention was implemented at the policy level

The assessment resulted in the set of 14 community-wide interventions that currently comprise the HI-5 Initiative. The initiative includes evidence-based interventions from a variety of sectors beyond health care and public health, such as transportation and education.

The Format

The HI-5 Initiative is a resource that can be used by public and private organizations to quickly assess the scientific evidence for measurable health outcomes in 5 years or less and evidence of cost effectiveness and/or cost savings over the lifetime of the population or earlier. While this initiative highlights approaches that meet these specific criteria, it is not a rigid set of recommendations from CDC. Rather, this tool is intended to be an additional evidence-based resource that local and state public health officials can consider in choosing interventions to achieve measurable health impact at the community or population level.

The HI-5 summary provides an overview of the initiative, and the evidence summaries provide more detailed information about each individual intervention. Each evidence summary includes the following information:

• What is the intervention?
• What is the public health issue? (health and cost burden)
• What is the evidence of health impact and cost effectiveness?
• Selected resources
• References

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^[1] The Community Guide rated an intervention as “Recommended” if, after conducting a systematic review of the available studies, it determined that they provided strong or sufficient evidence that the intervention was effective. Their systematic reviews consider several factors, including study design, number of studies, and consistency of the effect across studies.
^[2] County Health Rankings and Roadmaps rated an interventions as “Scientifically Supported” if it was supported by (1) or more systematic reviews, or at least (3) experimental studies, or (3) quasi-experimental studies with matched concurrent comparisons. Supporting studies had to include strong designs and statistically significant positive findings.
^[3] Auerbach, J. (2016). The 3 buckets of prevention. Journal of Public Health Management and Practice, 22(3), 215-218.
^[4] Frieden, T. R. (2010). A framework for public health action: the health impact pyramid. American journal of public health, 100(4), 590-595.

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