EvidenceBased Medicine:

1
Evidence-Based Medicine

• A Basic Primer
• Kevin Bradford, M.L.S.
• Clinical Information Librarian
• Instructor
• Medical College of Georgia
• April 2007

2
EBM Defined

• Evidence-based medicine (EBM) has been defined as
  "the conscientious, explicit, and judicious use
  of current best evidence in making decisions
  about the care of individual patients. The
  practice of evidence based medicine means
  integrating individual clinical expertise with
  the best available external clinical evidence
  from systematic research."(1)
• More recently, EBM has been described as the
  "integration of best research evidence with
  clinical expertise and patient values."(2)
• 1. David Sackett, et al. "Evidence Based
  Medicine What It Is and What It Isn't," BMJ 312,
  no. 7023 (1996) 2. David Sackett, et al.
  Evidence-Based Medicine How to Practice and
  Teach EBM (New York Churchill Livingstone, 2000)
  

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EBM Defined

• A total process beginning with knowing
• what clinical questions to ask
• how to find the best practice
• how to critically appraise the evidence for
  validity and applicability to the particular care
  situation.
• the best evidence and applying it with expertise
  in considering the patient's unique values and
  needs, and
• how to evaluate the effectiveness of care and the
  continual improvement of the process

4
What EBM Is Not

• Cookbook medicine
• A tool for administrators and insurers
• Restricted to randomized trials and systematic
  reviews
• Opposed to patient centered medicine

5
EBM The Literature

• Archie Cochrane
• Effectiveness and Efficiency Random Reflections
  on Health Services (1972)
• Because resources would always be limited, they
  should be used to provide equitably those forms
  of health care which had been shown in properly
  designed evaluations to be effective.

6
EBM Steps to Success
The base of the steps in the illustration is
where information usually starts with an idea or
laboratory research. As these ideas turn into
drugs and diagnostic tools they are tested in
laboratory models, then in animals, and finally
in humans. The human testing may begin with
volunteers and go through several phases of
clinical trials before the drug or diagnostic
tool can be authorized for use within the general
population. As you move up the steps, the
amount of available literature decreases--but
increases in its relevance to the clinical
setting.
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EBM The Literature

• Systematic Reviews usually focus on a clinical
  topic and answer a specific question. An
  extensive literature search is conducted to
  identify all studies with sound methodology. The
  studies are reviewed, assessed, and the results
  summarized according to the predetermined
  criteria of the review question. The Cochrane
  Collaboration has done considerable work in the
  area of systematic reviews.
• Meta-analyses will thoroughly examine a number of
  valid studies on a topic and combine the results
  using accepted statistical methodology as if they
  were from one large study. Some clinicians put
  Meta-analyses at the top of the pyramid because
  part of the methodology includes critical
  appraisal of the selected RCTs for analysis.
• Randomized controlled clinical trials are
  carefully planned projects that study the effect
  of particular therapies on actual patients. These
  include methodologies that reduce the potential
  for bias (randomization and blinding) and allow
  for comparison between intervention groups and
  control groups (no intervention).

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EBM The Literature

• Cohort Studies take a large population and follow
  patients who have a specific condition or receive
  a particular treatment over time and compare them
  with another group that has not been affected by
  the condition or treatment being studied. Cohort
  studies are observational and not as reliable as
  randomized controlled studies, since the two
  groups may differ in ways other than in the
  variable under study.
• Case Control Studies are studies in which
  patients who already have a specific condition
  are compared with people who do not. They often
  rely on medical records and patient recall for
  data collection. These types of studies are often
  less reliable than randomized controlled trials
  and cohort studies because showing a statistical
  relationship does not mean than one factor
  necessarily caused the other.
• Case series and Case reports consist of
  collections of reports on the treatment of
  individual patients or a report on a single
  patient. Because they are reports of cases and
  use no control groups with which to compare
  outcomes, they have no statistical validity.

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How To Structure Clinical Questions

• P Patient population / problem
• What are you trying to address
• Does gender/age influence clinical care
• I - Intervention / Area of interest
• What will you do for the patient?
• Drugs, surgery, diet, exercise
• C Comparison intervention / status
• Alternatives to your chosen intervention?
• Against other interventions, gold standard, or no
  treatment
• O Measurable outcome of interest
• What will be improved for the patient?
• Less risk of fracture, fewer hospitalizations,
  etc.
• Asking answerable clinical questions in D.L.
  Sackett, S.E. Straus, W.S. Richardson, W.
  Rosenberg, R.B. Haynes. Evidence-Based Medicine
  How to Practice and Teach EBM. New York
  Churchill Livingstone, 2000. p. 13-27

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How To Structure Clinical Questions

• Filtering the Evidence
• The Big Four
• Therapy
• Does it do more good than harm?
• Diagnosis
• How well does it confirm or exclude a diagnosis?
• Prognosis
• How well does it predict clinical course over
  time?
• Etiology
• How well does it identify a cause for a disease?

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How To Structure Clinical Questions

• Levels of Clinical Evidence in the Primary
  Literature

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How To Structure Clinical Questions

• MEDLINE
• Contains over 12 million citations to research
  articles, case reports, letters, editorials, and
  animal studies published in biomedical journals.
  However, many of these articles and reports are
  not clinically relevant.
• Search Filters for
• Therapy, Diagnosis, Prognosis, Etiology
• Recommended Optimized choice
• Restrict results to specific
• Population, Gender, Language
• Age Group, Publication Type

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Evaluating the Evidence

• Background/Literature review
• Study Design
• Control group or comparison group
• Randomization Blinding
• Population (size, traits) time frame
• Follow-up (gt80)
• Results of study
• Well defined outcome criteria
• Applicable to patients
• Purpose problem clearly stated
• Data Collection Procedures
• Method time frame specified
• Organization analysis of data
• Study Participants
• Selection Process Number of participants
• Nature of setting(s) utilized
• Results of study
• Impact on clinical practice
• Suggestions for future research

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Evaluating the Evidence

• Are the results of this study appropriate for my
  patients?
• Do my patients meet the inclusion and exclusion
  criteria?
• Is there any reason to believe that these results
  would not apply to my patients?
• Does the study include all of the outcomes I find
  clinically important?
• Do the treatment benefits outweigh the potential
  harm and/or costs?

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EBM Resources Bibliographic Databases

• Cochrane Database of Systematic Reviews
• A well-conducted, scientifically rigorous,
  systematic review on a clearly defined clinical
  topic is invaluable in the development of
  evidence-based practice because it 1 summarizes
  existing research, 2 defines the boundaries of
  what is known and what is not known, and 3
  helps us resolve inconsistencies among diverse
  pieces of research evidence.
• Cook D, Mulrow C, Haynes R. (1997). Systematic
  reviews synthesis of best evidence for clinical
  decisions. Ann Intern Med., 126(5), 376380
• Summarizes literature on key clinical topics
• Exhaustive searching (controlled trials,
  meta-analyses, protocols for in-process reviews)
• Analysis of all results for clinical impact
• Focus on questions related to therapy or
  treatment

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EBM Resources Bibliographic Databases

• Database of Abstracts of Reviews of Effectiveness
  (DARE)
• Structured abstracts of systematic reviews
• Commentary on clinical usefulness
• ACP Journal Club
• Methodologically sound clinically relevant
  study
• Value of article in clinical practice
• AHRQ Guidelines (National Guideline
  Clearinghouse) http//www.guideline.gov/
• Comprehensive database of evidence-based clinical
  practice guidelines and related documents

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EBM Resources Bibliographic Databases

• PubMed Clinical Queries
• A user-friendly approach to evidence-based
  searching of the Medline database.
• Pre-set research methodology filters enable the
  searcher to quickly locate the relevant
  literature on etiology, prognosis, diagnosis and
  therapy of diseases and diagnostics.
• The utilities in Clinical Queries are not
  intended to supply a comprehensive literature
  search, but are designed to provide information
  on those few "good" articles which will help the
  clinician make informed decisions.
• Divided into three sections
• Clinical Studies
• Systematic Reviews
• Medical Genetics

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Selected Point-of-Care Tools

• ACPs PIER (Physicians Information and Education
  Resources)
• Grades clinical recommendations based on the
  strength of the evidence available (via STAT!Ref)
• Over 300 modules focusing on the diagnosis and
  treatment of diseases
• Evidence indicators and standard tables
• Quarterly updates

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Selected Point-of-Care Tools

• DynaMed
• Contains more than 2,000 disease summaries.
  Diseases represented in the database reflect
  those most commonly seen in primary care.
• Levels of evidence included with every topic
  summary.