searching medline alex denby regional mi manager london medicines information service (northwick...
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Searching MedlineAlex DenbyRegional MI ManagerLondon Medicines Information Service(Northwick Park Hospital)
Main issues/problemsGeneralSearches produce irrelevant hits how to you find relevant hits for your topic?Difficulty finding good quality full text articlesNot using to full potential
Searching techniquesFinding/deciding which are the relevant search terms to use use of the MeSH /EMTREE termsMeSH terms not updated very often drug namesCAS no searches vs. free textFree text searching which field to useDifferent thesaurus for the 2 databasesNarrowing down searches
NLH Software Problems
Slow and crashes all the timeDoesnt reliably save articlesNo results displayed even though hits foundTakes a long time to do searches
PlanSearching basics a refresher (precourse material)What is Medline? (precourse material)Medical Subject Headings (MeSH)NLMs MeSH browserSearching toolsNLH software the basicsWorked examples
Searching MedlineUse indexing system - MeSH thesaurusControlled vocabulary with ~24,000 descriptorsEach represents a single conceptTree structure - hierarchalConstantly changing600+ added per year
Medical Subject HeadingsArticles 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 BrowserOpen 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
Kidney FailureDepressionChronic Fatigue SyndromePTSDFluoxetine
Searching ToolsExplode Includes everything below in the tree structureMajor descriptor (focus)Only includes articles where the MeSH heading (descriptor) is the main focus of the articleSelectSearches for the term without using Explode or Major but includes all subheadings.
Quick questionsWhat 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 (allowable qualifiers) refine your searchWhat 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 EffectsAnalysisChemistryDiagnostic useEconomicsHistory
e.g. AE: adverse effectsDU: diagnostic usePK: pharmacokineticsTU: therapeutic use
Check TagsAll relevant tags are attached to the articleThese are essentially used as limit functionsHumanChildAdultAgedMaleFemaleetc..
Check tagsLimits publication types
If you want to search for papers that are meta analyses use the publication type limit function. Articles will then be meta-analysesIf 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 ConceptsSearches for substances that are not defined in MeSH (i.e. dont have MeSH terms)Supplementary chemical record>30,000 substances undergoing clinical development but not all will become commercially available medicinesDepending on software - search by CAS registry number or free text
Quick questionWhat is directly above olanzapine in the MeSH tree?What is its CAS registry number?
Medline & MeSH Recap Successful searching is finding correct indexing termMeSH headingsScope NotesFocus/ExplodeSubheadings/Check TagsSupplementary concepts
National Library for Health softwareOpen Internet and type:http://www.library.nhs.uk/Default.aspxClick Login now (LHS of screen)Right click & then click on create a shortcutEnter Athens passwordClick on Healthcare Database Advanced Search and select Medline.
NLH softwareSearch one database at a timeMedline 1950 to date 2 options to search for terms:Thesaurus mappingBrowse headings
NLH softwareMajor /ExplodeTree structure SubheadingsSupplementary ConceptsLimitsShow 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 3Is 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)
General lack of confidence that the best results from a search are achieved
Formal training for a lot of people was either very brief or a long time agoMajority use NLHCouple OVID used by Scotland.
NHS Users in England will now on the most part access Medline via the NLH interface which is part of the National Core Content for the NHS England although previously this was DialogNHS Users in Wales and Scotland will access Medline using OVID. Remember that the NLH interface is relatively new and there may still be software issues with it, such as full text not being available, differences in hits if you combine results in different ways etc. People may have noticed that the MiCAL package uses the Pubmed interface, this is because it is needed to be usable by all in UK therefore for that purpose demonstrated Medline searching using PubMed.
We are going to be demonstrating Medline searching using NLH for the purpose of these sessions
Remember: it is the same database under each of the interfaces, so the principles of Medline searching are therefore the same whichever you use but the software and the way in which you do things may be slightly different I would advise anyone who uses Pubmed to where possible use OVID or NLH instead as the software is less intuitive (e.g. automatic explode function, different screens to navigate to yourself to find correct options, & without appropriate training may mistakenly be carrying out text word searches.)
If anyone wishes to discuss an interface other than NLH, can try & help during workshop.
If you search using free text rather than using an indexed terms, this could be a needle in haystack and often gives lots of irrelevant resultsfine if youve got the time to waste!
To use Medline effectively we must know how indexing works
The vocabulary/thesaurus for Medline MeSH (Medical Subject Headings) from National Library of Medicine (USA)
Descriptors/keywords/search terms are all the same thing
Single concept - Principal = each concept is labelled with a single term regardless of words author uses. Therefore each concept/topic has 1 MeSH term ONLY & these MeSH terms are consistently applied by indexers to the documents.Eg Lung neoplasm: lung carcinoma, lung cancerSo, if use MeSH searching is efficient. Free text searching usually yields poor results.
MeSH thesaurus consists of sets of terms in a hierarchy which start with a broad term and end at a much narrower term. MeSH is the same no matter which interface you use & all interfaces usually come with access to the NLMs MeSH.16 tree headings
Constantly changing 10 years ago erythropoietin endogenous compound. Now also known as a drug.
Therefore, check MeSH terms to ensure using correct term for the concept you want to search. The MeSH vocabulary is reloaded every year so searching MeSH term will limit the search to the date the term was introduced into MeSH.
24,767 descriptors in 2008 MeSH .More detail of 3 tier system on following slides. But:
MeSH descriptor = 1 single concept. Up to 20 per article (av. 10-12)
MeSH qualifier = clarifies the descriptor.
Check tags = eg human, female / male [indexers will check all tags that apply to the article]
V important that we understand the concepts being used so can chose the right term and combination to limit searches
The MeSH thesaurus was previously available as a v. large book (no longer available last printed in 2003). Now only available online. Updated yearly.
We will use the MeSH thesaurus to look at the principles involved in searching Medline, which apply to all interfaces used.
It is useful to use MeSH alongside OVID and NLH until you become more familiar with how to search.
Explain the 16 facets are the tops of the trees ie as broad as you can go.
By clicking on: e.g. disease then respiratory diseases, then lung diseases, then pneumonia etc you are working your way down the tree to more specific (less broad) terms however, this is not the easiest way to identify the term you are looking for
Show + signs
Then get everyone to click on return to entry page at top of the page.
Show front page with options and buttons to use at the bottom.Example: Kidney failure (use this example just to show difference in the 3 buttons show the data page in more detail with depression example)NB - Search defaults to all of the aboveleave as this when searchingOther searches:Find exact term only what youve typed exactly in that orderFind terms with ALL fragments (AND)Find terms with ANY fragments (OR) useful if struggling to find a term but does often give a very long non-specific list
Example: depression. Show that this is in the behavioural disorder tree. Show annotation, scope note, tree, and explain entry terms. (dont show allowable qualifiers yet this is explained later).Example: chronic fatigue syndrome. Show that this is not the MeSH term, but