1. Finding Current Best Evidence
Updated for the third edition of the Users' Guides to the Medical Literature.

2. Objectives
Be able to
Navigate through existing evidence-based medicine (EBM) resources
Distinguish the trustworthy from the less trustworthy
Maximize your chances of quickly finding answers based on current best evidence

3. Outline Clarify the question From evidence to EBM resources
Background vs foreground questions
The PICO framework
From evidence to EBM resources
Three classification systems
Evaluating trustworthiness
Three criteria for choosing and evaluating EBM resources
Using the pyramid of EBM resources
Three complementary levels of evidence
Formulating useful search terms
How to search
Broad vs narrow searches

4. Clarify the Question
The first step in searching for evidence is determining whether you are asking a background question or a foreground question.
Chapter 4 of the Users’ Guides to the Medical Literature and the accompanying Education Guide (What Is the Question?) cover this topic in more depth.

5. Use the PICO Framework Patients or population
Who are the relevant patients?
Intervention(s) or exposure(s)
For example, diagnostic tests, foods, drugs, surgical procedures, time, or risk factors
What are the management strategies we are interested in comparing or the potentially harmful exposures about which we are concerned?
Comparator
For issues of therapy, prevention, or harm, there will always be both an experimental intervention or putative harmful exposure and a control, alternative, or comparison intervention or state to which it is compared
Outcome
What are the patient-relevant consequences of the exposures in which we are interested?
We may also be interested in the consequences to society, including cost or resource use
Using the PICO framework will help you clarify your question. Please see Chapter 4 of the Users’ Guides to the Medical Literature and the corresponding Education Guide, What Is the Question?, for more on the PICO framework.

6. Why Clarify the Question?
To help you formulate the search terms and combine them into search strategies
Especially crucial when evidence is harder to find
To help you search for appropriate study designs and select the corresponding search filters (eg, Clinical Queries)
To help you ensure a feasible study design exists for your question

7. Outline Clarify the question From evidence to EBM resources
Background vs foreground questions
The PICO framework
From evidence to EBM resources
Three classification systems
Evaluating trustworthiness
Three criteria for choosing and evaluating EBM resources
Using the pyramid of EBM resources
Three complementary levels of evidence
Formulating useful search terms
How to search
Broad vs narrow searches

8. Three Classification Systems
Hierarchy of evidence
Level of processing of evidence
Categories of EBM resources

9. Moving Through the Categories
This figures shows how one moves from evidence to evidence-based resources.

10. Hierarchy of Evidence
A system of classifying and organizing types of evidence at the level of primary studies
For each type of question (therapy and harm, diagnosis, prognosis, and differential diagnosis), EBM provides a hierarchy of research designs
Within each design, some studies will provide evidence of higher quality than others

11. Levels of Processing Systematic reviews
Primary studies can be processed into systematic reviews
These save time and effort by searching for and appraising the quality of all relevant primary studies and, when appropriate, providing a summary estimate of the effects

12. Levels of Processing Clinical practice guidelines
A way of moving from evidence to recommendations for practice
This requires judging relative desirability of alternative courses of action
Must look at entire body of evidence, take into account patient values and preferences, and be mindful of resource considerations
Decision analyses and health technology reports may provide a similar level of processing of evidence

13. Pyramid of EBM Resources
Helps you determine where to start your search for high-quality evidence
Resources can be viewed in 3 broad categories:
Summaries and guidelines
Preappraised research
Nonpreappraised research

14. Summaries and Guidelines
Online summary resources
Summary of body of evidence at topic-level (not limited to a question, intervention, or outcome)
Examples: UpToDate, DynaMed
Databases of clinical practice guidelines
Often with actionable recommendations for clinical decision making
Regularly updated
Examples: Clinical Evidence, Best Practice, US National Guidelines Clearinghouse
More information on using summaries and guidelines, preappraised research, and nonpreappraised research to find answers to your question is given later on in this Education Guide.

15. Preappraised Research
Synopses of systematic reviews
Structured abstracts or 1-page summaries of selected reviews or studies
Examples: ACP Journal Club, McMaster PLUS, Cochrane
Systematic reviews
Synopses of studies
Various degrees of preappraisal
Continuously updated
Source of evidence alerts
Example: Evidence Updates
The various degrees of preappraisal include selection according to methodologic criteria, clinicians’ ratings, clinicians’ comments, and experts’ structured appraisal.

16. Nonpreappraised Research
Filtered studies
All primary studies with no preappraisal
Examples: PubMed (MEDLINE), CINAHL, CENTRAL
Unfiltered studies
Automatic filtering of databases for specific study designs or clinical content
Filter example: Clinical Queries in PubMed
CENTRAL, Cochrane Central Register of Controlled Trials; CINAHL, Cumulative Index to Nursing and Allied Health Literature.

17. Navigate All at Once
Federated search engines allow you to search efficiently across all 3 categories of resources simultaneously
Examples: ACCESSSS, Trip, Epistemonikos
ACCess to Evidence-based Summaries, Synopses, Systematic Reviews and Studies.
Additional resources can help clinicians link evidence to daily practice, such as clinical decision support systems. See Chapter 11.6 of the Users’ Guides to the Medical Literature for more information on clinical decision support systems.
An example of a search using ACCESSSS is provided later on in this Education Guide.

18. Outline Clarify the question From evidence to EBM resources
Background vs foreground questions
The PICO framework
From evidence to EBM resources
Three classification systems
Evaluating trustworthiness
Three criteria for choosing and evaluating EBM resources
Using the pyramid of EBM resources
Three complementary levels of evidence
Formulating useful search terms
How to search
Broad vs narrow searches

19. Three Criteria for Evaluating Resources
Based on current best evidence
Coverage and specificity
Availability and access

20. Current Best Evidence Citation that support statements
Can you distinguish statements that are based on high-quality vs low-quality evidence?
If not, dismiss the resource

21. Current Best Evidence Currency
What is the date of the most recent reference cited?
Process for keeping the resource up-to-date should be transparent
Date stamp for all pieces of evidence
Explicit mechanism used to screen for new findings

22. Current Best Evidence Actionable summaries and guidelines
Did the authors use a rating system to assess the risk of bias of cited studies and the quality of reviews?
Recommendations need to
Be based on entire body of existing evidence (ideally systematic reviews) and provide benefits and harms of available options
Use an acceptable system for grading strength of recommendations
Report effect estimates for patient-important outcomes to support clinical judgment and shared decision making
ADD EXAMPLE FROM CHAPTER WITH CITATION

23. Coverage and Specificity
Unlikely to find one-stop-shop for evidence
May need to use all levels of EBM pyramid
Summarized resources higher in pyramid take more time to develop; evidence may potentially be out of date
May need to look at preappraised research for more recent evidence
The lower you look in the pyramid, the larger, and often less specific, the resource
Collections of preappraised research geared to your area of practice may be helpful
Examples of collections of preappraised research focused on a specific field include Evidence-Based Mental Health and Evidence-Based Nursing.

24. Coverage and Specificity
Type of question affects choice of resource
For example, questions of harm or rare adverse events are less likely to be answered by resources focused on management issues informed primarily by randomized clinical trials, such as the Cochrane Database of Systematic Reviews

25. Availability and Access
Most trustworthy resources at the top of the pyramid are often most expensive
Access to subscriptions may be possible through professional associations, national libraries, or resources such as WHO’s InterNetwork Access to Research Initiative
Other options include searching open-access journals, writing to authors of an article for a copy, or contacting a colleague at an academic center
WHO, World Health Organization.
A directory of open-access journals is available at

26. Availability and Access
Free services, such as BMJ EvidenceUpdates (produced by McMaster PLUS), can alert you to new research findings
Some full-text articles are available through PubMed or Google Scholar
Caution: searching for only free full-text articles may lead to a partial, potentially biased view of the evidence

27. Access at the Point of Care
Ask your institution or professional organization for proxy server permission or remote access to EBM resources
That way, you will have direct access to evidence on your smartphone and tablet to enhance your evidence-based practice

28. Outline Clarify the question From evidence to EBM resources
Background vs foreground questions
The PICO framework
From evidence to EBM resources
Three classification systems
Evaluating trustworthiness
Three criteria for choosing and evaluating EBM resources
Using the pyramid of EBM resources
Three complementary levels of evidence
Formulating useful search terms
How to search
Broad vs narrow searches

29. Using the Pyramid
Three complementary levels to help you answer your questions
Summaries and guidelines
Preappraised research
Nonpreappraised research

30. Summaries and Guidelines
Start at the top of the pyramid
Summaries and guidelines aim to integrate the available body of evidence and provide actionable recommendations

31. Guidelines vs Summaries
Guidelines are scattered across journals and websites
US National Guideline Clearinghouse provides comprehensive search portal
High variability in trustworthiness of practice guidelines
Seek out guidelines that are transparent in how they process evidence and develop recommendations
The US National Guideline Clearinghouse can be accessed at

32. Decision Analyses
Process body of evidence in a way similar to guidelines
Help you map out options with outcomes and probabilities so that you can judge the benefits and harms of different treatment approaches

33. Preappraised Research
You might seek out preappraised research when
You do not find the answers you need in summaries or guidelines
You have reason to doubt what you found in the summaries or guidelines
You need more recent evidence published since the guideline or summary was last updated

34. Finding Preappraised Research
Specific databases, such as McMaster PLUS, contain studies and reviews that are methodologically sound and clinically relevant

35. Example: McMaster PLUS
The PLUS in McMaster PLUS stands for Premium LiteratUre Service.
Reproduced with permission of the Health Information Research Unit, McMaster University.

36. Synopses
The more relevant studies and systematic reviews are selected to become synopses (<1% of initial selection)
Usually 1-page, structured summary of research findings with expert commentary
Secondary evidence-based journals are a source for examples of synopses
Provide overview of strengths and weaknesses of a study

37. Start With Synopses
Start your search for preappraised research by looking for synopses because they summarize the body of evidence on a question
DARE and Cochrane Library are additional resources, along with McMaster PLUS
DARE, Database of Abstracts of Reviews of Effects.

38. Nonpreappraised Research
Research articles are stored in databases such as MEDLINE, EMBASE, CINAHL, or Web of Science
Searching casts a wide net
You can limit irrelevant studies using filters, such as Clinical Queries in PubMed
CINAHL, Cumulative Index to Nursing and Allied Health Literature; EMBASE, Excerpta Medica dataBASE.

39. Filters for PubMed Sensitivity, % Specificity, % PubMed Equivalent
Broad filter
99.9 52
search*[Title/Abstract] OR meta analysis[Publication Type] OR meta analysis[Title/Abstract] OR meta analysis[MeSH Terms] OR review[Publication Type] OR diagnosis[MeSH Subheading] OR associated[Title/Abstract]
Narrow filter 71 99
MEDLINE[Title/Abstract] OR (systematic[Title/Abstract] AND review[Title/Abstract]) OR meta analysis[Publication Type]
MeSH, medical subject headings.
These filters are not implemented in PubMed; the search strategy needs to be copy and pasted right after the search to optimally filter systematic reviews.
Reproduced with permission from the BMJ.

40. Searching All Levels at Once
To search all levels of the pyramid at the same time, use a federated search engine, such as ACCESSSS
ACCESSSS, ACCess to Evidence-based Summaries, Synopses, Systematic Reviews and Studies.

41. Example of a Federated Search
EBM Resources Searched in Parallel in ACCESSSS
Summaries
DynaMed
UpToDate
Best Practice
ACP Smart Medicine
Preappraised research
Synopses of systematic reviews
ACP Journal Club
Systematic reviews
McMaster PLUS (including Cochrane reviews)
Synopses of studies
McMaster PLUS
Nonpreappraised research
Filtered studies
Clinical Queries in PubMed
Unfiltered studies
PubMed (MEDLINE)
ACCESSSS, ACCess to Evidence-based Summaries, Synopses, Systematic Reviews and Studies; DARE, Database of Abstracts of Reviews of Effects.
Reproduced with permission of the Health Information Research Unit, McMaster University.

42. Searching on Google Lacks transparency
Not a reliable way to filter current best evidence from unsubstantiated sources
Useful for quickly finding answers to background questions and uncovering rare citations
But you may want to use Google Scholar for foreground questions
Possibly comparable to other databases
Provides greater access to free articles
Kulkarni  AV, Aziz  B, Shams  I, Busse  JW. Comparisons of citations in Web of Science, Scopus, and Google Scholar for articles published in general medical journals. JAMA. 2009;302(10):
Shariff  SZ, Bejaimal  SA, Sontrop  JM,  et al. Retrieving clinical evidence: a comparison of PubMed and Google Scholar for quick clinical searches. J Med Internet Res. 2013;15(8):e164.

43. Outline Clarify the question From evidence to EBM resources
Background vs foreground questions
The PICO framework
From evidence to EBM resources
Three classification systems
Evaluating trustworthiness
Three criteria for choosing and evaluating EBM resources
Using the pyramid of EBM resources
Three complementary levels of evidence
Formulating useful search terms
How to search
Broad vs narrow searches

44. Combining Search Terms
PICO Components
Potential Search Terms P
Patients with stable chronic bronchitis
COPD OR (chronic bronchitis) I
Any mucolytic agent
Mucolytic C
Placebo (and current best care)
Placebo O
Number of exacerbations, mortality
Exacerbation OR mortality
Level of the Pyramid
Examples of Search Strategies
Summaries and preappraised research
Chronic bronchitis mucolytic
COPD mucolytic
Nonpreappraised research
COPD mucolytic exacerbation
(COPD OR (chronic bronchitis)) AND mucolytic
(COPD OR (chronic bronchitis)) AND mucolytic AND exacerbation
(COPD OR (chronic bronchitis)) AND mucolytic AND (exacerbation OR mortality)
COPD, chronic obstructive pulmonary disease.
This table shows how to break down a question into its PICO components and corresponding search terms. “OR” and “AND” are Boolean operators in these searches.

45. How to Search
After breaking your question down into its PICO components, choose and combine search terms into variety of search strategies
Searches can be kept simple for top level of EBM resources, because they are relatively small and highly selective
More specific and structured searches are needed for nonpreappraised research

46. Searching Large Databases
Search terms should closely relate to components of PICO question
Sometimes this will be straightforward, such as “diabetes” or “diabetic” if your population is patients with diabetes
Sometimes it may be more complicated, such as “antithyroid drug therapy”
You might use “antithyroid” or combine drugs using Boolean operators: “carbimazole OR propylthiouracil OR methimazole”

47. Picking Search Terms
Part knowledge of subject area, part trial and error
Google might help you find appropriate search terms
Medical Subject Headings (MeSH) Thesaurus can help direct you to the wording that indexers use
Access the MeSH Thesaurus at

48. Broad vs Narrow Searches
If your search yields few results, broaden it (ie, increase the sensitivity)
Add synonyms
Use truncated terms with an asterisk, such as diabet* for diabetes, diabetic, etc

49. Broad vs Narrow Searches
If your search yields too many results, make it narrower (ie, increase the specificity)
Link more PICO components using Boolean operator AND
Add limits or filters such as Clinical Queries in PubMed

50. Refining Your Search Strategy
Ways to Increase Sensitivity
Ways to Increase Specificity
Many search terms for a similar PICO component, linked with “OR”
More PICO concepts linked with “AND”: (P) AND (I) AND (C) AND (O)
Truncated terms, wildcards (eg, diabet*, wom?n)
Use of NOT as Boolean operator to exclude irrelevant terms
Synonyms (pressure sore, decubitus ulcer)
Variant spelling (tumour, tumor)
Limits (date, age group, etc)
Explosion of MeSH terms
Methodolgic filters (Clinical Queries)
Use of PubMed “Related citations” or bibliography of relevant articles
Content filters (topic or disease specific)
MeSH, medical subject headings.

51. Finding Related Articles
Find 1 potentially relevant article and use “Related citations” feature in PubMed
Screen the new output and select “Related citations” for all other relevant studies
Keep track of your finds with the clipboard function on PubMed

52. Related Citations in PubMed
A, Link to “Related citations” from a relevant article. B, Dialogue box allowing user to send relevant articles to the clipboard. C, After having sent an article to the clipboard, it is labeled so in the output.
Reproduced with permission of the US National Library of Medicine.

53. Tips for Daily Practice
Map your accessible EBM resources
Choose which resources you would like to explore next, according to your needs
Bookmark these resources in all of your browsers
Subscribe to an alerting system
Train yourself on questions that are familiar to you and compare EBM resources
Keep track of your questions to enhance your learning and to help you reflect back on your evidence-based practice
Always keep the patient perspective

54. Created by Thomas Agoritsas, MD, Gordon Guyatt, MD, Kate Pezalla, MA, and Annette Flanagin, RN, MA

55. Terms of Use: Users Guides to the Medical Literature Education Guides
PowerPoint Usage Guidelines
JAMAevidence users may display, download, or print out PowerPoint slides and images associated with the site for personal and educational use only. Educational use refers to classroom teaching, lectures, presentations, rounds, and other instructional activities, such as displaying, linking to, downloading, printing, and making and distributing multiple copies of said isolated materials in both print and electronic format. Users will only display, distribute, or otherwise make such PowerPoint slides and images from the applicable JAMAevidence materials available to students or other persons attending in-person presentations, lectures, rounds, or other similar instructional activities presented or given by User.
Commercial use of the PowerPoint slides and images are not permitted under this agreement. Users may modify the content of downloaded PowerPoint slides only for educational (non-commercial) use; however, the source and attribution may not be modified. Users may not otherwise copy, print, transmit, rent, lend, sell, or modify any images from JAMAevidence or modify or remove any proprietary notices contained therein, or create derivative works based on materials therefrom. They also may not disseminate any portion of the applicable JAMAevidence site subscribed to hereunder through electronic means except as outlined above, including mail lists or electronic bulletin boards.