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Published byClement Wright Modified over 9 years ago
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Searching Medline Alex Denby Regional MI Manager London Medicines Information Service (Northwick Park Hospital)
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Main issues/problems General 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
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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
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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
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Searching Medline Use indexing system - MeSH thesaurus Controlled vocabulary with ~24,000 descriptors Each represents a single concept Tree structure - hierarchal Constantly changing 600+ added per year
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Medical Subject Headings Articles indexed by 3 tier system MeSH descriptor (MeSH heading) MeSH qualifier (MeSH subheading) Items mentioned (check tags) Articles are indexed & then double checked by another indexer must agree
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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”
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MeSH Examples Kidney Failure Depression Chronic Fatigue Syndrome PTSD Fluoxetine
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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.
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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?
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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
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e.g. AE: adverse effects DU: diagnostic use PK: pharmacokinetics TU: therapeutic use
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Check Tags All relevant tags are attached to the article These are essentially used as “limit” functions Human Child Adult Aged Male Female etc..
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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
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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
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Quick question… What is directly above olanzapine in the MeSH tree? What is its CAS registry number?
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Medline & MeSH Recap Successful searching is finding correct indexing term MeSH headings Scope Notes Focus/Explode Subheadings/Check Tags Supplementary concepts
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Accessing Medline? MEDLINE OVID MEDSCAPE SILVER PLATTER PUBMED NLH
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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.
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NLH software Search one database at a time Medline 1950 to date 2 options to search for terms: Thesaurus mapping Browse headings
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NLH software Major /Explode Tree structure Subheadings Supplementary Concepts Limits Show titles
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Worked example 1 Are there any papers specifically about the use of linezolid for the treatment of MRSA? (Workshop question 1)
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Worked example 2 Are there any review articles about inhaler use in asthmatic children under 4? (Workshop question 2)
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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)
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ANY QUESTIONS?
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