evidence based medicine lecture sandra a. martin, m.l.i.s. health sciences resource coordinator...

Evidence Based Medicine Lecture

Sandra A. Martin, M.L.I.S.Health Sciences Resource Coordinator

Instructor of Library ServicesJohn Vaughan Library Room 305B

marti004@nsuok.edu – 918-444-3263

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 http://www.nks.nhs.uk/.

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. 2010 Blackwell Publishing

Time period Accepted practice Shown to be harmful

Impact on clinical practice

From 500 bc Blood Letting 1820 Ceased in 1910

1957 Thalidomide for morning sickness in early pregnancy

1960 Withdrawn when first case report of severe malformations appeared

From 1900 Bed rest for acute low back pain

1986 Still advised by some doctors

1960s Benzodiazepines for mild anxiety

1975 “Diazepam” prescribing fell in 1990s due to severe dependence and withdrawal symptoms

Late 1990s Cox-2 inhibitors to treat arthritis

2004 Withdrawn following legal cases in the US

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

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

www.cebm.net

“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?

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 2420-2425

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 1996. Fourth edition published in 2010.

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

Integration of EBM into medical school curricula patient-doctor courses

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

New Approach Requires New Skills

Clinical question formulation Search and retrieval of best evidence Critical appraisal of study methods to determine validity

of results

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

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

Clinical Questions

Four Common Types Therapy/prevention Diagnosis Etiology Prognosis

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]?

PICO Model

P - Patient or population

I - Intervention

C - Comparison Intervention

O - Outcome

Possible Search Terms

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

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

Best Study Design for Type of Question

Type of Question Study Design

Therapy/prevention Randomized controlled trials

Diagnosis Prospective cohort, blind comparison to a gold standard

Prognosis Cohort, Case Control, Case Series

Etiology/Harm Cohort, Case Control, Case Series

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

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.

Levels of Evidence

Grade the quality of evidence based on the design of the clinical study

Variety of hierarchies in use

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

DynaMed and FirstConsult

Hierarchy of Published Evidence for Intervention StudiesLevel of Evidence Description Study Example

1 Randomized clinical trial with low study errors or a meta-analysis

Optic neuritis treatment trial N Engl J Med. 1992; 326:581-588

2 Randomized clinical trial with high study errors

Scatter laser photocoagulation for occult choroidal neovascularization Arch Ophthalmol. 1996; 114:1456-1464

3 Clinical trial with a control group, with nonrandom treatment allocation

Thrombolytic therapy for acute retinal arterial occlusion Am J Ophthalmol. 1992; 113:429-434

4 Intervention case series Macular translocation surgery for the treatment of CNVM and AMD Am J Ophthalmol. 1968; 66:597-603

5 Interventional case report Removal of a choroidal neovascular membrane Retina. 1994; 14:125-129

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

4S Hierarchy

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), 36-38. Retrieved 2-07-07 from http://ebm.bmj.com/cgi/reprint/6/2/36

6S Hierarchy

• Summaries: • Clinical Key• First

Consult• Dynamed

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

Clinical Key includes 3 Levels Plus Books and

Overviews

Summaries, Synthesis, Studies

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

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”

Glaucoma Summary

Evidence-based answer found in 1 minute, 39 seconds

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

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)?”

1:54

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

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

Review found in 15 seconds

Cochrane DSR

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

Appraisal Required by User

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

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

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

MEDLINE Indexing

Search Query

Boolean Connectors

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

Ovid MEDLINE Clinical Queries

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

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

If you need Help, contact Sandra

marti004@nsuok.edu