Tuesday, February 24, 2009

Searching PubMed & using subject headings

The previous posting dealt with checking how PubMed has interpreted the words you typed. A typical “translation” includes searching for those words (separately and as phrases) as well as a subject heading search.

But what are subject headings?

· Subject headings are added by indexers to the record when it is added to the database. The record describes the article: author, title, journal details, abstract and subject headings. The indexers read the article, identify the principal topics and add the standard subject headings to the record.

· They describe articles in a standardised way – eg, pressure sores, pressure ulcers, bed sores, bed ulcers are all described as decubitus ulcers

· Therefore a subject heading search for decubitus ulcers will pick up all the variations in the way the authors describe pressure sores, bed sores etc

· The words you type are translated into the appropriate subject heading. If you are unhappy with the subject heading, try a new search but describe the it in a different way

· PubMed explodes the subject heading: it searches for articles with the selected heading as well as articles with more specific headings on the same subject

· Click on the heading and you will see the tree (categories), which displays the narrower headings (more specific). For example, exploding Bereavement includes Grief in your search

· Use the MeSH Database in PubMed to carry out a subject heading search alone (ie excluding the word searches)

Use subject headings to:
· make your search more relevant – a subject heading will only be added if it is an important topic
· pick up the variations in describing the topic – the subject headings are standard
· gather narrower, related subjects into your search – when the subject heading is exploded

Be careful:
· In PubMed, the most recent articles don’t yet have subject headings, so you need to do word searches as well (default search)
· While subject headings are standardised, there can be differences in interpretation. For example, the topic “do not resuscitate” can be found with subject headings of “Resuscitation Orders”, “Refusal to Treat” and “ Withdrawal of Treatment”

More information on subject headings from the PubMed tutorial and the Information Seeking & Library Skills section on Moodle.

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