Medical Subject Headings (MeSH)
From HLWIKI Canada
 http://www.nlm.nih.gov/mesh/2011/mesh_browser/MeSHtree.L.html To browse other articles on a range of HSL topics, see the wiki index.
IntroductionSee also Medical vocabulary and PubMed - MEDLINE The Medical Subject Headings - MeSH thesaurus is a controlled vocabulary created by the National Library of Medicine (U.S.) to index, catalogue and search for biomedical information and documents. PubMed provides access to ~22 million indexed records from 5,600 worldwide journals in 37 languages; 60 languages for older journals. (See NLM Indexing Process). The 2012 MeSH Database contains 26,556 descriptors or MeSH and Sixteen (16) Major Categories or Trees. Every year, a new MeSH vocabulary is published by the NLM to take account of new concepts in the field of biomedicine. New MeSH Database in 2011
You can also find it helpful to view the MeSH Database section in the following tutorial: http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_490.html Polyhierarchic structureMeSH terms are arranged in a poly-hierarchic tree structure. At the top, broadest levels, there are major categories such as ""Anatomy" or "Organisms" and increasing levels of specificity at the bottom parts of the hierarchy such as "Metatarsal Bones" and "Conduct Disorder." With ~25,186 descriptors and more than 172,000 headings called Supplementary Concept Records, the MeSH vocabulary is one of the largest of its kind in the world. There are thousands of cross-references to assist in locating appropriate terms; Vitamin C, for example, leads searchers to Ascorbic Acid. The explode and focus functions for MeSH help to increase the recall and precision of biomedical searching. Explode and focusMEDLINE searchers may use MeSH terms at high levels of generality (mentioned as broadest categories above) or specificity (narrower terms at the bottom of the tree) depending on the goals of the search or needs of the user. Explode will retrieve articles indexed with the major heading and all specific, narrower terms that fall beneath it. Focus locates articles where the term is a major descriptor (not a minor one). Explode and focus can be used together to find articles where the major heading and terms underneath are the focus of the articles retrieved. Entry terms to MeSH descriptors are included in the MeSH record and consist of information such as variations in the form, word order, spelling and printed entry term. (There are historic reasons for this which go back to ELHILL days of searching MEDLINE over phone lines). Trade names of drugs and equipment are usually not printed but exist as non-print entry terms. When entry terms are used, PubMed substitutes it with the MeSH descriptor automatically. MeSH for indexingThe MeSH thesaurus is used by NLM librarians to index articles from ~5,600 international biomedical journals (see Peer review) in the MEDLINE database. Each citation in MEDLINE is given up to ten to fifteen MeSH terms to describe its content. Incidentally, MeSH are also used to provide subject headings for bibliographic records (books, audiovisual materials and digital items) in library catalogues. NLM staff revise and update the MeSH thesaurus annually. Subject librarians are responsible for areas in which they have knowledge and expertise. NLM incorporates new subject headings or terms from the biomedical literature itself and scans emerging areas and new terms regularly. Health professionals in various scientific disciplines are also consulted about any proposed changes to the MeSH vocabulary and there is close coordination with other health organizations who produce specialized vocabularies. SubheadingsIn Medline, there are 83 floating, allowable subheadings or qualifiers. These 83 topical qualifiers are used to bring out specific aspects or facets of biomedical topics during the indexing and information retrieval process. Some common subheadings include drug therapy, diagnosis, etiology, surgery, etc. To search for specific subheadings in OvidSP, enter your MeSH term followed by a forward slash and the subheading abbreviation - health care reform/ec for economics of health care reform. Post-coordinate searching is also possible and widely-used by health librarians in systematic review searching. (Certain pre-arranged "Families of Subheadings" can also be searched together and literally exploded.) Using MeSH in health-related searchingWhen MeSH terms are not known (or used), health librarians can use textwording and/or keywording. As relevant citations are eventually located, terms associated with these citations can be reviewed and used to rerun a new more structured MeSH-based search. Health librarians constantly restrategize and rerun searches using natural language (See Gault et al) because there may be no relevant MeSH created yet. Keyword searching is a useful way to teach novice searchers or when very current articles are needed. Why? MeSH terms may not yet be created, relevant papers may not yet be indexed or the indexing may not be applied consistently to retrieve everything on a topic. Using MeSH in health libraries
Canadian contextSpecific issues in Canada's health system are not well-addressed by MeSH due to the American bias in the controlled vocabulary. Geographic subdivisions - Canada, and the provinces - are recommended for issues pertaining to specific regions of Canada ie. HIV infection in the downtown Eastside of Vancouver, try "British Columbia" or "Canada"[MeSH] and "downtown eastside" [keyword]. References
See the Cushing/Whitney Library tutorial and The Basics of MeSH - NLM. (The 2011 MeSH was released in early 2011). |
