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Deconstructing Evidence-Based Medicine
Dani Hackner, MD
Associate Chair, Department of Medicine
Associate Director, Division of General Internal Medicine
Cedars Sinai Medical Center
Los Angeles, CA

"The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research."1

Let's break down the EBM concept into its parts. "Evidence" implies that this EBM attempts to use factual and validated sources. Grading of the quality and quantity of the evidence establishes groundwork for further analysis. This system of grading allows the process to scale to larger endeavors, to adapt new material supporting continuing problems, or to build approaches to new problems. However, different categories of evidence and different articles (diagnostic, therapeutic, guidelines, meta-analyses, etc.) require different methodological approaches. As much focus of EBM has been on the approach to evaluation as the content of evaluations. Perhaps more important than providing the materials for building, EBM provides the tools for constructing best practice models.

While EBM directs the practitioner to a more critical view of the literature and the roots of practice, the evidence-based orientation does not replace good practice, which is founded on clinical experience, patient-specific problems, and clinical judgment. EBM does emphasize that a base of reproducible, systematically tested, medical knowledge be recognized. It also requires that the clinician understands the strengths, weaknesses, and deficits in the literature. Because the clinical research literature lacks evidence to support or refute much practice, evidence-based medicine is not evidence-only practice or evidence-always practice. Essentially, EBM recommends the application of best evidence to base best practice in medicine in a measurable and reproducible way.

Growth in EBM
Evidence-based approaches have gained momentum, with national quality initiatives aimed at establishing benchmarks for practice, payors aiming to reducing costly practice variation, and professional organizations aiming to simplify complex and cumbersome clinical workups by teasing out the effective from the merely traditional. As a result, "interest in evidence-based medicine has grown exponentially since the coining of the term in the early 1990s2,3 and has led to calls to increase the teaching of evidence-based medicine at the undergraduate and postgraduate levels."3,4

Systematic approaches have been endorsed by many national and regional organizations, such as the U.S. Preventive Services Task Force (USPSTF), Canadian Task Force on Preventive Health Care, the Society of Critical Care Medicine, the American Society of Health-System Pharmacists, and others. These approaches have led to what David Eddy refers to as evidence-based individual decision-making or evidence-based guidelines.5

USPSTF established by the Public Health Service, systematically reviews clinical research in order to assess preventive measures, such as screening tests, counseling, and preventive medications. It conducts rigorous, impartial assessments of the scientific evidence for the effectiveness of a broad range of clinical preventive services, including screening, counseling, and preventive medications. Its recommendations are considered the "gold standard" for clinical preventive services. The mission of the USPSTF is to evaluate the benefits of individual services based on age, gender, and risk factors for disease; make recommendations about which preventive services should be incorporated routinely into primary medical care and for which populations; and identify a research agenda for clinical preventive care. (

The Canadian Task Force and its website are "designed to serve as a practical guide to health care providers, planners and consumers for determining the inclusion or exclusion, content and frequency of a wide variety of preventive health interventions, using the evidence-based recommendations of the Canadian Task Force on Preventive Health Care (CTFPHC)." (

The National Guideline ClearinghouseT (NGC) is an initiative of the Agency for Healthcare Research and Quality (AHRQ), of the U.S. Department of Health and Human Services. NGC was originally created by AHRQ in partnership with the American Medical Association and the American Association of Health Plans (now America's Health Insurance Plans [AHIP]). Its goal is to disseminate evidence-based clinical practice and educational materials, with an emphasis on detailed practice guidelines. (

The American Society of Health-System Pharmacists sponsors evidence-based learning initiatives to help pharmacists identify evidence-based resources, analyze the quality of research, and decide how the evidence fits into clinical decision-making. (

The Society of Critical Care Medicine (SCCM) has taken the lead on evidence-based approaches in the care of sepsis patients. It has applied bundles, algorithms, and guidelines. SCCM has also endorsed individual decision-making as part of the process. The Surviving Sepsis campaign is both an educational effort on the content of their material as well as a decision-making educational process that encourages evidence-based risk stratification of patients at a very early stage of illness. This particular initiative bundles simple, often-overlooked evidence-based practices and also simplifies complex care plans to avoid practice that is not safe or is unrelated to positive outcomes. (

EBM is not without its critics who charge that the overwhelming result has been to dilute valid literature, distract clinicians from individual assessment, automate care and remove clinicians from the bedside. Does EBM allow third parties to have a hand in setting standards that should be in clinicians' hands? Studies that alone may have withstood challenge may be undermined by meta-analysis. Weak studies have been aggregated in "synthetic" approaches challenging large, landmark studies. Moreover, practice that can no longer be tested in randomized, double-blind, clinical trials may never be considered "Grade A." The advocates of practice variation argue that innovation is squeezed out in an effort to fit all practice into a guideline box. Some critics also charge EBM with a kind of hypocrisy because its use is challenging for even the most sophisticated academic, but still applied in many cases by less skilled professional staff not tasked with decision-making. Does EBM really take the chefs out of the kitchen and replace them with short-order cooks?6

The Consumer of Evidence
Why the hunger for EBM? At the kitchen door stands the voracious consumer of medical information, who nibbles on snippets from the loftiest medical literature and gorges on suspect material from the lowest strands of the commercial web. The dyspeptic patient-consumer now demands from the healthcare professional an appraisal of the conflicting information. What sources inform the clinical plan of care? The consumer's questions drive clinicians to separate good evidence from bad, then to make recommendations that have external validation, and finally to demonstrate why particular decisions, diagnoses, and treatments apply.

Ironically, consumers may drive some providers toward increasing reliance on evidence to guide practice and to demanding that clinicians demonstrate effective, focused, and defensible clinical practice. In certain cases, the evidence may truly mitigate against lawsuits and reduce risks of peer review. However, the immediate hazard is being publicly downgraded against published benchmarks. From its inception, EBM may have been an attempt by academics to leverage the scientific method in a clinical setting. In its current manifestation as a guided, organized approach to practice, EBM is an open book for the clinician and consumer to review.7,8


  1. Sackett, David L. quoted in the American College of Cardiology, Accessed 5-4-06 09:45.
  2. Guyatt GH. Evidence-based medicine. ACP Journal Club 1991;114:A-16.
  3. Straus SE, McAlister FA. Evidence-based medicine: a commentary on common criticisms. CMAJ. 2000 Oct 3;163(7):837-41.
  4. Bordley DR, Fagan M, Theige D. Evidence-based medicine: a powerful educational tool for clerkship education. Am J Med 1997;102:427-32.
  5. Eddy DM. Evidence-based medicine: a unified approach. Health Affairs (Millwood). 2005 Jan-Feb;24(1):9-17.
  6. Timmermans S, Mauck A. The promises and pitfalls of evidence-based medicine. Health Affairs (Millwood). 2005 Jan-Feb;24(1):18-28.
  7. Evidence-based clinical practice in evolution. ACP Journal Club. 2002 Mar-Apr. 136(2): A11.
  8. Clinical expertise in the era of evidence-based medicine and patient choice. ACP Journal Club. 2002 Mar-Apr;136:A11.

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