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Evidence Based Medicine Lecture Sandra A. Martin, M.L.I.S. Health Sciences Resource Coordinator Instructor of Library Services John Vaughan Library Room.

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Presentation on theme: "Evidence Based Medicine Lecture Sandra A. Martin, M.L.I.S. Health Sciences Resource Coordinator Instructor of Library Services John Vaughan Library Room."— Presentation transcript:

1 Evidence Based Medicine Lecture Sandra A. Martin, M.L.I.S. Health Sciences Resource Coordinator Instructor of Library Services John Vaughan Library Room 305B –

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3 Existing knowledge can prevent… Waste Errors Poor quality clinical care Poor patient experience Adoption of interventions of low value Failure to adopt interventions of high value Source: Sir Muir Gray, Chief Knowledge Officer of Britain’s National Health Service. Quoted on

4 Harmful practices once supported by expert opinion Source: Adapted from How to read a paper: the basics of evidence-based medicine. 4 th edition. By Trisha Greenhalgh Blackwell Publishing Time periodAccepted practiceShown to be harmful Impact on clinical practice From 500 bcBlood Letting1820Ceased in Thalidomide for morning sickness in early pregnancy 1960Withdrawn when first case report of severe malformations appeared From 1900Bed rest for acute low back pain 1986Still advised by some doctors 1960sBenzodiazepines for mild anxiety 1975“Diazepam” prescribing fell in 1990s due to severe dependence and withdrawal symptoms Late 1990sCox-2 inhibitors to treat arthritis 2004Withdrawn following legal cases in the US

5 Information Retrieval for Evidence Based Patient Care Using research findings versus conducting research Retrieving and evaluating information that has direct application to specific patient care problems Selecting resources that are current, valid and available at point-of-care Developing search strategies that are feasible within time constraints of clinical practice

6 Learning Objectives At the end of the presentation, you will be able to: Define evidence-based medicine (EBM) Understand the Five Steps to practice EBM Use the 6S hierarchy to conduct an efficient search for the best evidence Access online pre-appraised resources Locate print and online tools to assist in critical appraisal of individual studies Practice the Five Steps in clinical settings

7 “Evidence-based medicine is the integration of best research evidence with clinical expertise and patient values” Sackett DL, Rosenberg WMC, Gray JAM, Haynes RB, Richardson WS: Evidence based medicine: what it is and what it isn’t. BMJ 1996;312:71-2. Patient Concerns Clinical Expertise Best research evidence EBM What is EBM?

8 Evolution of EBM in the Literature Term first appeared in the literature in a 1991 editorial in ACP Journal Club Volume 114, Mar-April 1991, pp A-16 Seminal article by the Evidence-Based Medicine Working Group published in JAMA Volume 268, No. 17, 1992, pp

9 Fundamentally new approach becomes widely recognized JAMA published a series of Users’ Guides to the Medical Literature that served as the first learning tools Courses were developed in residency training and medical school curricula The first handbook, Evidence-Based Medicine: How to practice and teach EBM, by Sackett, et al, was published in Fourth edition published in New York Times listed EBM as one of its ideas of the year in 2001 BMJ listed EBM as one of the 15 greatest medical milestones since 1840

10 Integration of EBM into medical school curricula patient-doctor courses

11 EBM Process – 5 Steps 1. ASK: Convert need for information into answerable question 2. ACQUIRE: Find best evidence to answer the question 3. APPRAISE: Critically appraise evidence for validity, impact, and applicability 4. APPLY: Integrate evidence with clinical expertise and patient values 5. ASSESS: Evaluate own effectiveness

12 New Approach Requires New Skills Clinical question formulation Search and retrieval of best evidence Critical appraisal of study methods to determine validity of results

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15 Background v Foreground Knowledge Both types of knowledge needed Varies over time Depends on experience with condition Point A: Student – limited experience Point B: Resident – growing clinical experience Point C: Attending – extensive experience Note: Diagonal line shows “we’re never too green to learn foreground knowledge, nor too experienced to outlive the need for background knowledge” Source: Evidence-based medicine: how to practice and teach it. 4 th edition. By Straus, et. al. Churchill Livingstone Elsevier

16 Answerable Questions Arise in patient care setting and are:  Important to the patient’s well being  Fill gaps in your clinical knowledge  Feasible to answer in time available

17 Clinical Questions Four Common Types  Therapy/prevention  Diagnosis  Etiology  Prognosis

18 Therapy Question Example In patients with primary open angle glaucoma or ocular hypertension [Patient/Population], do topical medications to reduce intraocular pressure [Intervention] versus no treatment [Comparison Intervention], delay visual field defect progression [Outcome]?

19 PICO Model P -Patient or population I - Intervention C -Comparison Intervention O - Outcome

20 Possible Search Terms Primary open angle glaucoma, POAG, Ocular hypertension, OHT, topical medications, intraocular pressure, IOP, visual fields, VF

21 Evidence Based Retrieval 1.Find the answer that is supported by valid studies appropriate to the type of question and that is available in a timely manner. 2.Requires search terms plus best study design for question plus highest level of evidence

22 Best Study Design for Type of Question Type of QuestionStudy Design Therapy/preventionRandomized controlled trials DiagnosisProspective cohort, blind comparison to a gold standard PrognosisCohort, Case Control, Case Series Etiology/HarmCohort, Case Control, Case Series

23 Is All Evidence Created Equal? Small portion of medical literature is immediately useful to answer clinical questions Understanding “wedge or pyramid of evidence” is helpful in finding highest level of evidence High levels of evidence may not exist for all questions due to nature of medical problems and research limitations

24 As you move up the pyramid the amount of available literature decreases, but it increases in its relevance to the clinical setting. Source: Sackett, D.L., Richardson, W.S., Rosenberg, W.M.C., & Haynes, R.B. (1996). Evidence-Based Medicine: How to practice and teach EBM. London: Churchill-Livingstone.

25 Levels of Evidence Grade the quality of evidence based on the design of the clinical study Variety of hierarchies in use

26 American Academy of Family Physicians SORT  Level A Systematic reviews of randomized controlled trials including meta- analyses Good-quality randomized controlled trials  Level B Good-quality nonrandomized clinical trials Systematic reviews not in Level A Lower-quality randomized controlled trials not in Level A Other types of study: case control studies, clinical cohort studies, cross sectional studies, retrospective studies, and uncontrolled studies  Level C Evidence-based consensus statements and expert guidelines

27 DynaMed and FirstConsult

28 Hierarchy of Published Evidence for Intervention Studies Level of EvidenceDescriptionStudy Example 1 Randomized clinical trial with low study errors or a meta- analysis Optic neuritis treatment trial N Engl J Med. 1992; 326: Randomized clinical trial with high study errors Scatter laser photocoagulation for occult choroidal neovascularization Arch Ophthalmol. 1996; 114: Clinical trial with a control group, with nonrandom treatment allocation Thrombolytic therapy for acute retinal arterial occlusion Am J Ophthalmol. 1992; 113: Intervention case seriesMacular translocation surgery for the treatment of CNVM and AMD Am J Ophthalmol. 1968; 66: Interventional case reportRemoval of a choroidal neovascular membrane Retina. 1994; 14:

29 Key developments that streamlined the practice of EBM Advances in ease of accessing and understanding information Development of preprocessed (preappraised) tools Improvements in search interfaces to MEDLINE Collaboration between EBM Working Group and National Library of Medicine in development of hedges, “clinical queries” tool, that filters search results to specific study types and levels of evidence Dissemination of systematic reviews of primary studies and growth of the Cochrane Collaboration

30 4S Hierarchy

31 Highest Level of Evidence - Critically Appraised Content Evidence Based Summaries Dynamed, Clinical Key, First Consult, UptoDate ACP Journal Club, DARE Cochrane Database of Systematic Reviews Clinical Key & Ovid MEDLINE limited to Study Types and Clinical Queries SOURCE: Haynes, R. B. (2001). Of studies, syntheses, synopses, and systems: the “4S” evolution of services for finding current best evidence. Evidence-Based Medicine, 6 (2), Retrieved from

32 6S Hierarchy Summaries: Clinical Key First Consult Dynamed

33 New Resource – Clinical Key Full text access to 1,000 books and 500 journals in every medical and surgical specialty Ophthalmology – Over 60 full text books Includes 12 Content Types Access to information at all levels from topic overview to evidence-based data in one search Smart search engine matches first few letters of search word/words to relevant clinical content No complicated search strategies or Boolean connectors Easier than Google – but with reliable, evidence-based results

34 Clinical Key includes 3 Levels Plus Books and Overviews Summaries, Synthesis, Studies

35 Summaries FirstConsult –Available through NSU subscription to Clinical Key for iPhone or iPad only –Create a personal account in Clinical Key –Download the app from the Apple app store –Login with your Clinical Key username and password –Summaries are detailed and include sections on Differential Diagnosis –Eyes and Vision topics well covered

36 Summaries DynaMed –Summaries for more than 3,000 topics –Monitors >500 medical journals and systematic review databases –Updated daily –Each article evaluated for clinical relevance and scientific validity –Includes “graded evidence”

37 Glaucoma Summary Evidence-based answer found in 1 minute, 39 seconds

38 Summaries UptoDate –Evidence based summaries of over 9,500 topics in over 20 specialties, over 250,000 references, and drug database –Ophthalmology not one of the specialties –Good for information on systemic conditions –Updated continuously

39 Clinical Question “In hypertensive patients older than 75 with atrial fibrillation (P), does the use of warfarin (I), compared to aspirin (C), result in fewer strokes (O)?”

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43 Syntheses Cochrane Database of Systematic Reviews (DSR) –Part of the Cochrane Library (1996) –916 completed reviews, 1905 protocols –Among the highest level of evidence upon which to base treatment decisions –Includes Dx since 2008 –Eyes & Vision Research Group Contains over 165 reviews

44 Systematic Review Analyzes data from several primary studies to answer a specific clinical question Provides search strategies and resources used to locate studies Includes specific inclusion and exclusion criteria (results in less bias) Meta-Analysis (subclass) statistically summarizes results of several individual studies Access full text of Cochrane reviews in OVID

45 Review found in 15 seconds Cochrane DSR

46 Copyright: The Cochrane Library, Copyright 2009, The Cochrane Collaboration

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48 Appraisal Required by User

49 Primary (Original) Studies Articles that report results of original research investigations Conclusions supported by data and reproducible methodology Require time to acquire and appraise Good Sources: Ovid MEDLINE and Clinical Key

50 When to search for original studies If the other “S’s” don’t provide the answer, search for original studies “Do it yourself” appraisal territory You must appraise quality of the study or find analysis in evidence based summary Limit to “Study Type” in Clinical Key or “Clinical Queries” in Ovid MEDLINE

51 Databases MEDLINE –Premiere biomedical database from the NLM (National Library of Medicine) –Covers 1946-present –Indexes >4000 international biomedical journals –Full text available for many articles –Access through Ovid

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53 MEDLINE Indexing

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55 Search Query

56 Boolean Connectors

57 MEDLINE Search Limits Limit search results to study type –Randomized controlled trials –Clinical trials In OVID, limit by “Clinical Queries” Appraise study for validity and relevance

58 Ovid MEDLINE Clinical Queries

59 Levels of Evidence in Ovid based on AAFP SORT  Level A = “Specificity” in Ovid Clinical Queries Systematic reviews of randomized controlled trials including meta- analyses Good-quality randomized controlled trials  Level B = “Sensitivity” in Ovid Clinical Queries Good-quality nonrandomized clinical trials Systematic reviews not in Level A Lower-quality randomized controlled trials not in Level A Other types of study: case control studies, clinical cohort studies, cross sectional studies, retrospective studies, and uncontrolled studies  Level C Evidence-based consensus statements and expert guidelines

60 Take Home Points Focused clinical question (PICO) reveals your search terms Start your search at top of 6S hierarchy and work down Be aware of the filter, i.e., levels of evidence, speed of updating Look at more than one resource in the hierarchy. Findings may differ Apply in clinical settings; Assess your progress

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