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6S Model of Evidence Resources

Introduction

The 6S Model of Evidence-Based Resources can be used to help select resources to answer foreground questions related to patient care. Since Systems resources are still in development, it is most efficient to start by searching Summary resources, such as clinical practice guidelines, DynaMed, and UpToDate. If you do not find an answer to your foreground question in a Summary resource, you will work your way down the 6S Model to Synopses of Syntheses, Syntheses, Synopses of Single Studies, and Single Studies resources.

6S Model of Evidence Resources

The 6S Model of Evidence Resources is a pyramid with six levels; from the top of the pyramid the levels are Systems, Summaries, Synopses of Syntheses, Syntheses, Synopses of Single Studies, and Single Studies. Below the model is a section of foundational resources, which includes background resources and integrated clinical tools. An arrow, labeled Level of Evidence, points from the bottom of the pyramid by the Single Studies level to the top by the Systems level.

Pyramid modified from: DiCenso A, Bayley L, Haynes RB. ACP Journal Club. Editorial: Accessing preappraised evidence: fine-tuning the 5S model into a 6S model. Ann Intern Med. 2009;151(6):JC3.
 

Key Characteristics of the 6S Model of Evidence Resources:

  • The 6S Model is a hierarchy of evidence-based resources organized by methodology.
     
  • Each level appraises and incorporates the evidence from levels found below it on the pyramid. This makes the level of evidence higher as you go up the pyramid.
     
  • The pre-appraised evidence resources near the top of the pyramid are generally more efficient to search, so they are a good place to start when you have a clinical question.
     
  • The Foundational Resources below the pyramid are not part of the 6S Model because they do not have transparent evidence-based methodologies.
     

Caveats of the 6S Model of Evidence Resources:

  • For each topic, the resources become more scarce as you go up the pyramid.
     
  • The higher up the pyramid, the more general the information becomes. For example, a Summary Resource may not provide evidence that matches all of your patients characteristics and co-morbidities.
     
  • There will be a time lag between when evidence is published and when it is located, appraised, and incorporated in other evidence-based resources farther up the pyramid. 

Systems Resources at the top of the 6S model are still emerging and evolving in clinical practice. In the future, Systems resources will automatically link a patient's characteristics to the matching best evidence and management recommendations. 

Once they are available, Systems resources will make evidence-based practice more efficient since health care professionals will not need to search other resources independently.

 

6S Model of Evidence Resources with the top level, Systems, emphasized. The remaining 5 levels (Summaries, Synopses of Syntheses, Syntheses, Synopses of Single Studies, and Single Studies) and Foundational Resources are also shown.

Caveat

Current generative artificial intelligence tools (such as ChatGPT) are not systems level evidence-based resources as presented at the top of the 6S model.

To explore risks and ethical considerations of applying current artificial intelligence tools in evidence-based practice, read:

  • Holm S. On the Justified Use of AI Decision Support in Evidence-Based Medicine: Validity, Explainability, and Responsibility [published online ahead of print, 2023 Jun 9]. Camb Q Healthc Ethics. 2023;1-7. doi:10.1017/S0963180123000294. MGetIt link to the article.
  • Morath B, Chiriac U, Jaszkowski E, et al. Performance and risks of ChatGPT used in drug information: an exploratory real-world analysis [published online ahead of print, 2023 Jun 1]. Eur J Hosp Pharm. 2023;ejhpharm-2023-003750. doi:10.1136/ejhpharm-2023-003750. MGetIt link to the article.

Summary Resources:

  • Follow explicit and transparent methodologies to identify, appraise, and present the evidence from resources found below it on the 6S pyramid.
     
  • Provide evidence grades to quickly indicate the strength and quality of evidence.
     
  • Are the highest level that currently includes fully developed resources available for use.
     
  • Provide excellent coverage of topics with substantial evidence available.
     
  • May provide limited coverage of new techniques and emerging topics. In that case, continue searching for evidence in resources further down the pyramid.

 

6S Model of Evidence Resources with the second level, Summaries, emphasized. The remaining 5 levels (Systems, Synopses of Syntheses, Syntheses, Synopses of Single Studies, and Single Studies) and Foundational Resources are also shown.

 

Summary Resources Available at University of Michigan

  • DynaMed
    • A point-of-care tool that provides high-level recommendations, evidence grades, and summaries of the evidence. 
    • Utilizes a transparent, seven step process to develop and update entries.
       
  • UpToDate
    • A point-of-care tool that provides high-level recommendations and links out to references.
       
  • PubMed
    • Limit search to Practice Guidelines to retrieve clinical practice guidelines published in the health sciences literature

Synopses of Syntheses briefly describe and appraise the systematic reviews and meta-analyses found at the Syntheses level, including the review's methodology, key findings, and the strength of the findings.

Synopses of Syntheses can save time compared to reading and analyzing the full review yourself.

 

6S Model of Evidence Resources with the third level, Synopses of Syntheses, emphasized. The remaining 5 levels (Systems, Summaries, Syntheses, Synopses of Single Studies, and Single Studies) and Foundational Resources are also shown.

 

Synopses of Syntheses Resources Available at University of Michigan

  • Cochrane Clinical Answers (via the Cochrane Library)
    • Cochrane Clinical Answers use the evidence in Cochrane Reviews to provide concise, evidence-based answers to clinical questions.
    • Cochrane Reviews are selected for development of Cochrane Clinical Answers based on four criteria, including volume of evidence available and priority level of the Cochrane Review.

Syntheses Resources:

  • Systematically identify and critically appraise all primary research on a particular clinical question in order to make practice recommendations.
     
  • Key examples include systematic reviews and meta analyses. Meta analysis is a type of systematic review in which the data from all of the included studies are pooled and a statistical analysis is run as if it were one large study.
     
  • Systematic reviews differ from general review articles because they adhere to a rigorous methodology that aims to minimize bias and assemble a comprehensive body of evidence on the topic.
     
  • Are time and labor intensive to write and update; there may not be a Synthesis on a topic or the newest primary research may not be synthesized in the review.
6S Model of Evidence Resources with the fourth level, Syntheses, emphasized. The remaining 5 levels (Systems, Summaries, Synopses of Syntheses, Synopses of Single Studies, and Single Studies) and Foundational Resources are also shown.

 

Syntheses Resources Available at University of Michigan

  • Cochrane Database of Systematic Reviews (via Cochrane Library) 
    • A database of systematic reviews, review protocols, and editorials produced by Cochrane.
    • Cochrane Reviews are conducted following the methodological standards of the Cochrane Handbook for Systematic Reviews of Interventions.
       
  • PubMed 
    • The literature in PubMed includes both Syntheses and Single Studies.
    • Limit your search to Syntheses using the Article Type limits in the menu to the left of the search results (i.e., the checkboxes next to Systematic Review and Meta-Analysis).
       
  • BMJ Evidence-Based Medicine
    • A journal that publishes primary research, syntheses, and opinion pieces related to evidence-based medicine.
    • The Evidence Synthesis collection includes systematic reviews, scoping reviews, living reviews, and more.

Synopses of Single Studies provide brief summaries of high-quality original research. Synopses of Single Studies are a more efficient source of evidence than original research because they balance brevity and succinct detail.

Synopses are not available for all research studies; if you cannot find one on your topic you will need to search a Single Studies resource for evidence.

 

6S Model of Evidence Resources with the fifth level, Synopses of Single Studies, emphasized. The remaining 5 levels (Systems, Summaries, Synopses of Syntheses, Syntheses, and Single Studies) and Foundational Resources are also shown.

 

Synopses of Single Studies Resources Available at University of Michigan

  • BMJ Evidence-Based Medicine
    • A journal that publishes primary research, syntheses, and opinion pieces related to evidence-based medicine.
    • The EBM Verdict collection includes Synopses of selected Single Studies that provide conclusive results.
       
  • BMJ Evidence-Based Nursing
    • A journal that applies criteria to select valid research relevant to nursing practice.
    • The Commentaries column includes Synopses of selected Single Studies and Syntheses.

Single Studies Resources:

  • Cover a broader range of clinical problems than pre-appraised evidence-based resources, which may allow you to find literature that more closely matches your patient's characteristics and your clinical question.
     
  • Provide access to the most recent publications that have not been integrated into other resources yet.
     
  • Are the least efficient to search and apply in evidence-based practice since the literature base is large and studies are not pre-appraised.
     
  • May not include a primary research study that matches your clinical question. Despite the vast number of primary studies published, there is no guarantee that a satisfactory study has been completed.
 
6S Model of Evidence Resources with the sixth level, Single Studies, emphasized. The remaining 5 levels (Systems, Summaries, Synopses of Syntheses, Syntheses, and Synopses of Single Studies) and Foundational Resources are also shown.

 

Single Study Designs

The Single Studies level of the 6S Model of Evidence Resources includes a wide variety of study designs (e.g., randomized controlled trials and cohort studies). Research study designs are often organized into hierarchies, such as the Study Design Pyramid on the Levels of Evidence page of this guide.

The type of study design available to provide the best evidence for your clinical question may vary based on the research question, ethical considerations, resourcing limitations, and study quality.

 

Single Studies Resources Available at University of Michigan

  • PubMed
    • PubMed is a literature database that provides access to over 30 million biomedical and life science citations.
    • Use the Article Types limits (to the left of the results) to narrow your search to particular study designs.
      • For example, click the checkbox next to Randomized Controlled Trial in the limits menu.
      • Customize the list of Article Type limits using the "Additional filters" button.
    • Consider using Clinical Queries to apply filters to retrieve clinical studies on therapy, diagnosis, prognosis, etiology, or clinical prediction guides.

 

  • CINAHL
    • Cumulative Index to Nursing and Allied Health Literature (CINAHL) is a literature database for nursing and allied health professionals, students, educators, and researchers.
    • The "Search Options" on the Advanced Search page lists the available search limits, including a checkbox for Randomized Controlled Trials.

 

  • Embase
    • Embase is a literature database that provides strong coverage of biomedical and pharmaceutical citations.
    • Use the Study Types limits (to the left of the results) to narrow your search to particular study designs.

 

  • PsycInfo
    • PsycInfo is a literature database for articles, book chapters, and technical reports in the field of psychology. It also covers psychological and behavioral aspects of related disciplines, such as medicine, psychiatry, nursing, pharmacology, and sociology.
    • The "Search Options" on the Advanced search page lists the available search limits, including Document Type (e.g., Journal Article and Dissertation) and Methodology (e.g., Empirical Study and Clinical Trial).

 

Reach out to the informationist for your specialty for more information on literature databases available at the University of Michigan.

 

Access Articles with MGetIt

The video below demonstrates how to use the MGetIt link to access articles through the University of Michigan Library. 

Foundational Resources include high-quality background resources and integrated clinical tools. Even though Foundational Resources often reference original research and syntheses, they are not included in the 6S model because they do not follow transparent, evidence-based processes to create content.

Consider using Foundational Resources, such as medical textbooks and drug resources, for background questions.

 

6S Model of Evidence Resources with the Foundational Resources below the pyramid emphasized. The levels of the 6S pyramid are also shown above the Foundational Resources (i.e., Systems, Summaries, Synopses of Syntheses, Syntheses, Synopses of Single Studies, and Single Studies).

 

Foundational Resources Available at University of Michigan

  • AccessMedicine
    • A multimedia platform that includes core textbooks, videos, and case studies.
    • Use the "McGraw Hill Medical" menu to access the platforms available for other specialties.

 

  • ClinicalKey
    • A platform that includes drug monographs, thousands of medical textbooks, and practice guidelines.
    • Create a free account within the resource to access PDFs of book chapters.

 

  • Lexicomp Online
    • A robust resource for drug information that includes drug monographs, clinical practice guidelines, and tools.
    • Key tools available in Lexicomp include: Drug I.D., Interactions checker, Trissel’s IV Compatibility, and Calculators.

 

  • VisualDx
    • VisualDx is a point-of-care diagnostic system, providing high-quality images to help identify and classify visible patient symptoms.

 

  • Nursing Reference Center
    • A system designed to provide evidence-based information for nursing practice, education, and research at the point-of-care.
    • Nursing Reference Center's broad range of features include evidence-based care sheets, nursing practice and skill worksheets, and nursing care plans.