in Evidence-biased Medicine
ผศ.นพ. อนิรธ
ุ ภัทรากาญจน์
Aims of Literature Search
• To solve clinical problems (EBM)
• To search for existing knowledge in order to conduct
a research
• To update knowledge
“5A” of Evidence-Based Practice
ASSESS
problem
ASK
the right question
ACQUIRE
search for the best
available evidence
APPRAISE
the evidence
ASSESS
Decision making
APPLY
Professional
experience
Pathophysiology
Pharmacology
Psychology
Organizational
issues
Costs
Politics
etc
General Search Strategy
Search the best available database
Define relevant, searchable terms
Design search strategy
No
Relevant results?
Yes
Poor
Summarize & Appraise the evidence
GOOD
Apply the evidence
Well-built Clinical Question : PICO
•P
•I
•C
•O
•
Patients or population
Intervention
Comparison
Outcome
Type of question
– Therapy, etiology, prognosis, diagnosis, etc.
• Study design
– Descriptive, case-control, RCT, etc.
Example
อยากทราบว่ าในผู้ป่วยเด็กที่เป็ น diabetic nephropathy จะมีอตั รา
การเกิด ESRD ต่ างกันหรือไม่ ระหว่ างกลุ่มที่ได้ รับ ACEI ร่ วมกับ ARB
เปรียบเทียบกับกลุ่มที่ได้ รับ ACEI เพียงอย่ างเดียว
Formulate the question
• Patients : children with diabetic nephropathy
• Intervention : ACEI+ARB
• Comparison : ACEI
• Outcome : ESRD
• Question : therapy
• Design : systematic review, RCT
Tools
• Hardware
– A computer with (good & fast) online access
• LAN, MODEM (ADSL, cable)
• Software
– Web browser
• Internet Explorer, FireFox, Opera
– Adobe Reader® (latest version from adobe.com)
– Reference management softwares
•
• EndNote®, ProCite®, Reference Manager®
Electronic databases
– On-line
– Off-li
Medical Clinical Evidence Sources
•
•
•
•
•
•
•
Expert
• References
Standard textbooks
• References of the references
Teaching documents
• Index books
Meeting presentation
 Science citation index
Proceedings of presentation  Index medicus (1879)
Thesis
 Excerpta medica (1948)
Current contents
• Electronic databases
Search Exhaustively
•
•
•
•
•
•
•
Electronic databases
Printed journals, hand-search
Unpublished articles
Expert seeking
Pharmaceutical companies data
Grey literature
General internet search engines: google, yahoo, msn,
altavista, itools
Internet Search Engines
• General
- Google
- Yahoo
- MSN
- Live
- Altavista
- Excite
- HotBot
- Lycos
- Go.com
- Ask.com
• Special search engine
•
- Clusty.com
- Kartoo.net
Metasearch engines
- Gahooyoogle.com
(search Yahoo,
Google,all at once)
- Arrowsearch.net
- Copernic Agent
Electronic Databases
• Bibliographic databases
•
Medline
Embase
Scopus
Science Citation Index
LILACS
Open access databases
Grey literature databases
Web search engines
Google Scholar
Scirus
Bibliographic Database
• Medline
 About 5,000 journals
 Free access via PubMed
 http://www.ncbi.nlm.nih.gov/pubmed/
 Now include “Oldmedline”
 Oldest article in 1865 Trans Am Ophthalmol Soc
 PubMed Central (http://www.ncbi.nlm.nih.gov/pmc/)
 Free full-text
 Mostly articles in English from North American region
Bibliographic Databases (Thai)
• Siriraj: Thai Medical Index (http://www.medlib.si.mahidol.ac.th/)
• Chula: Thai Index Medicus (http://www.library.md.chula.ac.th/)
• Other Thai databases
– ศูนย์บริการความรูท้ างวิทยาศาสตร์และเทคโนโลยี (http://www.stks.or.th/web/)
– ห้องสมุดงานวิจยั สานักงานคณะกรรมการวิจยั แห่งชาติ (http://www.riclib.nrct.go.th/)
Bibliographic Databases (Thai)
• Thai journal pointer
– Journal Link (www.journallink.or.th)
• Thai journal citation index center (TCI)
(www.kmutt.ac.th/jif/public_html/)
Pre-filtered Clinical Resources
• Cochrane library
– Online access:
http://www.thecochranelibrary.com/view/0/index.html
– Offline access: CD updated quarterly
• ACP Journal Club (previous Best Evidence)
– www.acpjc.org
• Clinical Evidence
– www.clinicalevidence.com
• Evidence-based Medicine (EBM Online)
– http://ebm.bmj.com/
Pre-filtered Clinical Resources
• UpToDate
– www.uptodate.com
– CD updated every 4 months
Multidisciplinary Clinical Resources
• Ovid.com
• MDConsult.com
– Full-text of “Clinics of North America” Journals
– Full-text of “Year Books”
– Not all have pdf files
Electronic Text Books
• Harrison Online
– www.harrisonsonline.com
– www.harrisonsmed.com (store)
What is PubMed?
• A web-based retrieval system developed by NCBI (a
part of Entrez retrieval system)
• Free version of MEDLINE on the web
NIH
National Institutes of Health
NLM
National Library of Medicine
NCBI
National Center for
Biotechnology Information
PubMed Database
• A database of bibliographic information drawn primarily from the
life sciences literature
• PubMed contains links to
– Full-text articles at participating publishers' Web sites
– Other third party sites such as libraries and sequencing centers
• All citations in MEDLINE are assigned MeSH Terms and
Publication Types from NLM's controlled vocabulary.
What Does MEDLINE Cover?
• Not only medicine
– medicine
– nursing
– dentistry
– veterinary medicine
– health care system
– preclinical sciences e.g., molecular biology
How Big is MEDLINE?
• > 5,000 biomedical journals
• > 16 million citations back to 1865
• Published in the U.S. and 70 other countries.
• Coverage is worldwide, but most records are from
English-language sources or have English abstracts
• MEDLINE contains citations, not full-text articles
(PubMed provides links to full-text)
A basic search
1. Identify the key concepts for your search.
Example: Find citations about bronchodilators for
treating asthma in children.
The key concepts are bronchodilators, asthma and
children
2. Enter terms into the search box.
3. Press the Enter key or click Search.
Combining search terms with Boolean operators
• AND retrieves results that include all the search
terms.
• OR retrieves results that include at least one of the
search terms.
• NOT excludes the retrieval of terms from your
search.
Combining search terms with Boolean operators
• Examples
– Find citations on DNA that were authored by Dr. Crick in
1993: dna [mh] AND crick [au] AND 1993 [dp]
– Find citations on the effects of heat or humidity on
multiple sclerosis: (heat OR humidity) AND multiple
sclerosis
– Find citations about arthritis excluding the Publication
Type Letter: arthritis NOT letter [pt]
Automatic term mapping (ATM)
• Untagged terms that are entered in the search box
are matched (in this order) against
– MeSH (Medical Subject Headings) translation table
– Journals translation table
– Full Author translation table
– Author index
– Full Investigator (Collaborator) translation table
– Investigator (Collaborator) index
Automatic term mapping (ATM)
• To bypass ATM, using the following formats:
– Enclose the phrase in double quotes: “kidney allograft”
– Use a search tag: kidney allograft[tw]
– Use a hyphen: first-line
– Truncate: kidney allograft*
Truncating search terms
• Example flavor*
Finds terms that begin with the root term flavor, such
as flavored, flavorful, flavoring, etc.
MeSH
• NLM's controlled vocabulary thesaurus.
• Terms naming descriptors in a hierarchical structure
that permits searching at various levels of
specificity.
Example of MeSH
Example of MeSH
Example of MeSH
Search Field Descriptions and Tags
Search Field Descriptions and Tags
• Example
– Search for articles about influenza published in the New
England Journal of Medicine
– influenza [mh] AND n engl j med [ta]
Searching by author
• Enter the author’s name in the format of last name
followed by initials. Omit punctuation.
– Examples smith ja jones k
• If only the author's last name is entered, tag the
name with the author search field [au]
• Full author names may be searched for citations
published from 2002
Searching by journal title
• Enter in the search box one of the following:
– full journal title (e.g., molecular biology of the cell)
– title abbreviation (e.g., mol biol cell)
• To find full journal names, use the Journals database
• Use the Single Citation Matcher
(http://www.ncbi.nlm.nih.gov/corehtml/query/static/citmatch.html )
Limits
• by dates, type of article, languages, species, gender,
subsets, ages, text options, and specific search
fields.
http://www.ncbi.nlm.nih.gov/pubmed/
Combining searches using History
• Previous searches can be combined or used in
subsequent searches
http://www.ncbi.nlm.nih.gov/pubmed/
Summary Display
Abstract Display
Medline Display
เพื่อบันทึก file ในรูปแบบของ medline ในกรณี ที่ต้องการทางานส่วน reference manager
เพื่อบันทึก article ที่คดั เลือกไว้ เก็บรวบรวมในส่วน clipboard
Search Strategy Tips
• Identify the key concepts.
• Determine alternative terms for these concepts, if
needed.
• Refine your search to dates, study groups, etc., as
appropriate.
• Practice helps. Strategies and styles will differ
according to personal choice and professional
discipline.
• เด็กชายอายุ 5 เดือน มีประวัติ UTI พัฒนาการปกติ ตรวจร่างกายพบ
เพียง phimosis ผล imaging studies เป็ นปกติ มารดาได้รบั คาแนะนา
ให้ใช้ steroid cream ทาหนังหุม้ ปลายให้ทารก จึงมาขอคาแนะนาจาก
ท่าน
• Patients : infants with phimosis
• Intervention : circumcision
• Comparison : no circumcision
• Outcome : Urinary tract infection
• Question : therapy
• Design : systematic review, RCT
• Patients : infants with phimosis
• Intervention : steroid
• Comparison : no intervention
• Outcome : retractable prepuce
• Question : therapy
• Design : systematic review, RCT
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