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Searching Medline

Searching Medline. Alex Denby Regional MI Manager London Medicines Information Service (Northwick Park Hospital). Main issues/problems. General Searches produce irrelevant hits – how to you find relevant hits for your topic? Difficulty finding good quality full text articles

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Searching Medline

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  1. Searching Medline Alex Denby Regional MI Manager London Medicines Information Service (Northwick Park Hospital)

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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”

  8. MeSH Examples • Kidney Failure • Depression • Chronic Fatigue Syndrome • PTSD • Fluoxetine

  9. 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.

  10. 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?

  11. 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

  12. e.g. AE: adverse effects DU: diagnostic use PK: pharmacokinetics TU: therapeutic use

  13. Check Tags • All relevant tags are attached to the article • These are essentially used as “limit” functions • Human • Child • Adult • Aged • Male • Female • etc..

  14. 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

  15. 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

  16. Quick question… • What is directly above olanzapine in the MeSH tree? • What is its CAS registry number?

  17. Medline & MeSH Recap • Successful searching is finding correct indexing term • MeSH headings • Scope Notes • Focus/Explode • Subheadings/Check Tags • Supplementary concepts

  18. Accessing Medline? SILVER PLATTER PUBMED MEDLINE OVID NLH MEDSCAPE

  19. 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.

  20. NLH software • Search one database at a time • Medline 1950 to date • 2 options to search for terms: • Thesaurus mapping • Browse headings

  21. NLH software • Major /Explode • Tree structure • Subheadings • Supplementary Concepts • Limits • Show titles

  22. Worked example 1 • Are there any papers specifically about the use of linezolid for the treatment of MRSA? (Workshop question 1)

  23. Worked example 2 • Are there any review articles about inhaler use in asthmatic children under 4? (Workshop question 2)

  24. 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)

  25. ANY QUESTIONS?

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