Updated January 2007

Framework for Making Systems Changes

Evidence-Based Decision-Making

Evidence shows that many of the problems associated with diabetes can be successfully managed, reduced, or even prevented. The application of emerging therapies and self-care behaviors can make a dramatic impact on the quality of life of patients with diabetes. Documented evidence from applied clinical research regarding the diagnosis, prognosis, and therapy of diabetes-related medical problems is available to guide clinical decision-making.

An important way to affect change in health care systems is to develop skills and capacity among individuals and organizations that apply an evidence-based approach to diabetes-related clinical care.

Experienced clinicians use a wide range of judgments, decisions, actions, and recommendations in the practice of medicine that include:

• knowledge
• past experience
• empathy, compassion, and respect for the patient's wishes
• an appreciation of common care practice patterns within the community
• and an understanding of human biology.

The practice of evidence-based decision-making involves integrating these elements with the best available clinical evidence from a systematic review of research. However, a literature search only informs the clinician of the available evidence and says nothing about helping the clinician make the best decision in light of the patient's preferences and values.

Principles of Evidence-Based Decision-Making

1. Use a systematic and explicit method of searching the literature and retrieving the evidence
    
2. Synthesize the body of evidence
   Narrative quantitative (meta analysis) methods can be used to compile the body of evidence. Evidence is not limited to any one type of literature. While randomized clinical trials may be favored designs for generating high levels of evidence, evidence may also be generated from case studies, pertinent guidelines, high-quality recommendations, authoritative consensus statements, or observational studies such as cohort studies with comparison groups. Much of traditional medical practice has not yet undergone rigorous scientific study and high-quality evidence may not exist to support conventional knowledge or practice.
    
3. Rate the quality of the body of evidence
   Many different rating systems have been proposed. Most rating systems will attempt to provide the reader with an assessment of the study design (randomized clinical trial, cohort study, case-control study, consensus panel, etc.) and the study quality (i.e. internal validity, quality of the supporting evidence on a topic).

Since 1999, the Agency for Healthcare Research and Quality has been mandated to look at "methods or systems to rate the strength of the scientific evidence underlying health care practice, recommendations in the research literature and technology assessments."

A common rating system is the following ABC rating scale.

• Level A (randomized controlled trial/ meta-analysis):
  High quality randomized controlled trial that considers all important outcomes. High-quality meta-analysis (quantitative systematic review) using comprehensive search strategies.
• Level B (other evidence):
  A well-designed, nonrandomized clinical trial. A nonquantitative systematic review with appropriate search strategies and well-substantiated conclusions. Includes lower quality randomized controlled trials, clinical cohort studies, and case-controlled studies with nonbiased selection of study participants and consistent findings. Other evidence, such as high-quality, historical, uncontrolled studies, or well-designed epidemiologic studies with compelling findings, is also included.
• Level C (consensus/expert opinion):
  Consensus viewpoint or expert opinion. Expert opinion is sometimes the best evidence available.

Note: Other letter scales may be used. For example, the U.S. Preventive Services Task Force is charged with searching, reviewing, and grading evidence, and making recommendations for prevention practices. They use an ABCDF rating scale with different categories from those above. The American Diabetes Association uses an ABCD rating scale. The Endocrine Society uses a combination of numbers (1 = we recommend or 2 = we suggest) that indicates the strength of the recommendation and symbols (stars) to grade the evidence upon which the recommendation is made.

4. Generating recommendations based on the quality of the body of the evidence as well as patient values, preferences and resource constraints.

Limitations of Evidence-Based Decision-Making

Limitations that are universal to science and medicine include shortage of coherent and consistent scientific evidence, difficulties in translating the evidence into individualized clinical practice, inadequate system organization, and financial constraints. Limitations that are unique to the practice of evidence-based decision-making include the need for new skills to conduct literature searches and critically appraise the evidence, as well as time for busy clinicians to digest the literature. These can be overcome, however, through identification and use of pre-appraised resources. A critical point to keep in mind is that evidence is dynamic and needs to be revisited on a regular basis.

The special edition of Health Affairs, sponsored by the Agency for Healthcare Research and Quality, provides a variety of perspectives on the challenges and potential rewards of building and using a stronger evidence base for health care decisions. www.ahrq.gov/clinic/healthaff.htm

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