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Assessing the Strength of the Evidence

Prevention Best Practices

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Wyoming Overview

Approach For The Literature Review

WYSAC researchers began the literature review by searching for environmental prevention strategies indexed in the Cochrane Drug and Alcohol Reviews and the National Registry of Evidence-based Programs and Practices (NREPP) registry.

If a systematic review could be located in one of these sources, researchers moved on to review the next strategy.

If no evidence could be located, they continued by searching multiple peer-reviewed journal databases using keywords particular to that prevention strategy (such as “medication assisted treatment”). Databases included PubMed/Medline and PsycInfo (EBSCOhost).

If researchers still did not have sufficient evidence, they searched Google Scholar and retrieved the most up-to-date and highly-cited articles.

In an effort to locate the most prominent and recent publications, researchers restricted their search to articles published after 1999. However, if no articles were located, they expanded the search to include earlier literature. This review process was not designed to be an exhaustive search of the literature. Instead, the goal was to find the most established strand of research within the scientific literature related to each strategy. Older literature was included when it clearly had a meaningful and long-lasting impact upon research. This was demonstrated through multiple citations across subfields within the discipline related to each strategy.

Finally, in the event that no articles or literature could be located, they performed a Google search for grey literature.

Evidence Sources

No Evidence Found

This evidence category indicates that there is inadequate research to evaluate the effectiveness of the strategy. A strategy with no evidence may be relatively new and not yet evaluated, or the peer-reviewed articles on the strategy may lack quantitative analysis of outcomes.

Grey Literature

Grey literature refers to written material that is produced by an institute and/or organization that has not been published in peer-reviewed, academic journals.

Single Published Study

This evidence category refers to a single published study that has appeared in a peer-reviewed, academic journal.

Numerous Published Studies

This evidence category refers to strategies with evidence from multiple studies that have appeared in peer-reviewed, academic journals.

Systematic Review

A systematic review is a critical assessment and evaluation of all research studies that address a particular issue (US Department of Health and Human Services, n.d.). In most cases, researchers use an organized method of locating, assembling, and evaluating a given body of literature on a particular topic using a set of specific criteria (US Department of Health and Human Services, n.d.).


Meta-analysis refers to a method of combining data from multiple research studies that is similar to a systematic review, but which includes a statistical process that combines findings from individual studies (US Department of Health and Human Services, n.d.).

Cochrane Review

Cochrane Reviews are systematic reviews published by the Cochrane Collaboration—an international network of healthcare professionals that prepares, maintains, and promotes the accessibility of systematic reviews on a range of health topics. Cochrane Reviews cover primary research in human health care and health policy and are internationally recognized as the highest standard in evidence-based health care (The Cochrane Collaboration, 2012).


The National Registry of Evidence-Based Programs and Practices (NREPP) is a service of the Substance Abuse and Mental Health Services Administration (SAMHSA) that provides a searchable online registry of mental health and substance abuse interventions that have been reviewed and rated by independent reviewers. The purpose of NREPP is to assist the public in identifying scientifically-based approaches to preventing and treating mental and/or substance use disorders that can be readily disseminated to the field (National Registry of Evidence-Based Programs and Practices, 2012).