Searching Medline
Alex DenbyRegional MI ManagerLondon Medicines Information Service(Northwick Park Hospital)
Main issues/problemsGeneral Searches produce irrelevant hits – how to you
find relevant hits for your topic? Difficulty finding good quality full text articles Not using to full potential
Searching techniques Finding/deciding which are the relevant search
terms to use –use of the MeSH /EMTREE terms MeSH terms not updated very often – drug
names CAS no searches vs. free text Free text searching which field to use Different thesaurus for the 2 databases Narrowing down searches
NLH Software Problems
Slow and crashes all the time Doesn’t reliably save articles No results displayed even though hits
found Takes a long time to do searches
Plan
Searching basics – a refresher (precourse material)
What is Medline? (precourse material) Medical Subject Headings (MeSH) NLM’s MeSH browser Searching tools NLH software – the basics Worked examples
Searching Medline
Use indexing system - MeSH thesaurusControlled vocabulary with ~24,000
descriptorsEach represents a single conceptTree structure - hierarchalConstantly changing600+ added per year
Medical Subject Headings
Articles indexed by 3 tier systemMeSH descriptor (MeSH heading)MeSH qualifier (MeSH subheading) Items mentioned (check tags)Articles are indexed & then double
checked by another indexer must agree
MeSH Browser Open the Internet and type:
http://www.nlm.nih.gov/mesh/MBrowser.html
Right click & then click on “create a shortcut”
Now click on “Navigate from tree top”
MeSH Examples
Kidney Failure Depression Chronic Fatigue Syndrome PTSD Fluoxetine
Searching Tools Explode
Includes everything below in the tree structure Major descriptor (focus)
Only includes articles where the MeSH heading (descriptor) is the main focus of the article
Select Searches for the term without using Explode or
Major but includes all subheadings.
Quick questions…
What is the correct MeSH term to use for angina?
And if you exploded this term, what term(s) would you be also including in your search?
Subheadings (qualifiers)
Subheadings (allowable qualifiers) refine your search What aspect of the main heading is the author writing
about or discussing? Look at the definitions of the subheading e.g.:
Administration and Dosage Adverse Effects Analysis Chemistry Diagnostic use Economics History
e.g. AE: adverse effects
DU: diagnostic use
PK: pharmacokinetics
TU: therapeutic use
Check Tags All relevant tags are attached to the
article These are essentially used as “limit”
functions Human Child Adult Aged Male Female etc..
Check tags
Limits – publication types
If you want to search for papers that are meta analyses use the publication type limit function. Articles will then be meta-analyses
If you use the MeSH heading ‘meta-analysis as a topic’ from tree E the articles you will get will be about meta-analysis as a study design(methods etc..)
Look at the MESH browser for definitions
Supplementary Concepts
Searches for substances that are not defined in MeSH (i.e. don’t have MeSH terms)
Supplementary chemical record >30,000 substances undergoing clinical
development – but not all will become commercially available medicines
Depending on software - search by CAS registry number or free text
Quick question…
What is directly above olanzapine in the MeSH tree?
What is its CAS registry number?
Medline & MeSH Recap
Successful searching is finding correct indexing term
MeSH headings Scope Notes Focus/Explode Subheadings/Check Tags Supplementary concepts
Accessing Medline?
MEDLINEOVID
MEDSCAPE
SILVER PLATTER
PUBMED
NLH
National Library for Health software
Open Internet and type:http://www.library.nhs.uk/Default.aspx Click “Login now” (LHS of screen) Right click & then click on “create a
shortcut” Enter Athens password Click on “Healthcare Database Advanced
Search” and select Medline.
NLH software
Search one database at a time Medline 1950 to date 2 options to search for terms:
Thesaurus mappingBrowse headings
NLH software
Major /Explode Tree structure Subheadings Supplementary Concepts Limits Show titles
Worked example 1
Are there any papers specifically about the use of linezolid for the treatment of MRSA?
(Workshop question 1)
Worked example 2
Are there any review articles about inhaler use in asthmatic children under 4?
(Workshop question 2)
Worked example 3
Is there any evidence that minocycline is more effective than any of the other tetracyclines that are licensed for the treatment of acne (tetracycline, lymecycline, oxytetracycline, doxycycline)?
(Workshop question 5)
ANY QUESTIONS?
