Tuesday, August 16, 2011

MeSH (Medical Subject Headings)

MeSh, or Medical Subject Headings, is the controlled vocabulary created by the National Library of Medicine for indexing purposes. Many medical institutions and schools use these specialized terms in order to organize and allow easier access to their holdings. Searching by these headings or their subheadings allows you to find articles and books on topics you are interested in that you wouldn't find with a keyword search. As I said in the post on searching PubMed (http://ghntslibrary.blogspot.com/2011/07/searching-pubmed.html) your search phrase may not be in the title, abstract, or text. You can't know exactly what words or phrases the individual authors are going to use. Catalogers solve this problem by assigning a phrase from the controlled vocabulary to all these similar articles.

Try doing a "Title/Abstract" and a "MeSH Terms" search on "Medication Errors" and compare the results. "Title/Abstract" gives you 2257 results while the "MeSH Terms" search gives you 8691. That means that the Title/Abstract search is missing 6434 relevant articles because the exact phrase you were looking for isn't mentioned. While you don't want to look through over 8000 results, this at least gives you some leeway in narrowing things down by using further search terms and limiters.

Her's the homepage of PubMed. Click on the MeSH Database link at the lower right. Here you can search for the exact terms to use.

Click to enlarge.
You can search for a MeSH the same way you search for anything else. It will even give you options as you type.


Next you will be taken to that Subject Headings page. This breaks down what category your term is in and what subheadings it has. Subheadings are further classifications within the main category. Using these terms in the MeSH Subheadings field on the advanced search page allows you to create even more specific searches.

You can see where Medication Errors falls in the Health Care Category.
You can also search from the MeSH database. Notice the search box to the right of the page. You can search for everything labeled Medication Errors by checking the box "Restrict to MeSH Major Topic". If you don't want to search the categories further down the line, which in this case includes "Medication Reconciliation", check the box "Do not include MeSH terms found below this term in the MeSH hierarchy". You can check both of these together to restrict your search to Medication Errors.
You can also search the subheadings by checking the ones you like. If you check any of these you cannot also check the Restrict box.

Once you've checked the boxes that interest you, click the Add to Search Builder button and it will appear in the search box.


You can add more than one term and you can even use the Boolean AND, OR, or NOT by adding a term you don't want to look for with the NOT button chosen. Then you can hit Search PubMed and you will be taken to the search results page. Remember to click the free full text button at the right to see what articles are immediately available.

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