Exploring PubMed

PubMed is one of the world's premier databases for scholarly journal literature in the biomedical sciences. It includes over 30 million citations, dating from 1946 to the present. PubMed consists mostly of the MEDLINE database (about 87%), with the remainder being made up of several small subsets of citations outside of MEDLINE. PubMed provides citations and abstracts, and when available, links to the full-text through publishers, academic libraries, and PubMed Central.

The most popular way to search PubMed is to simply enter a word or phrase in the search box, and click Search. PubMed will automatically map your search terms to the corresponding subject headings and keywords. By adjusting the sorting method and adding a few filters, you can quickly and easily generate a list of relevant results. The following video will show you how this works.

As you saw in the previous video, you can refine and focus the results of a Basic Search simply by applying a few filters, such as language, species, type of article, and age group.

However, sometimes you need to run a more precise search. One way to accomplish that is to search using subject terms alone, omitting the simultaneous keyword searches that are automatically done in a Basic Search.

In PubMed, the subject terms are referred to as Medical Subject Headings, or MeSH terms. They are derived from a controlled vocabulary called the MeSH Thesaurus.

Just as search tags are used to describe the content of photos posted online, MeSH terms serve to describe the content of journal articles. Searching on MeSH terms eliminates the need to search on all the possible synonyms and spelling variations for a given term, so it will usually generate more precise results. The next video will show you how to run a MeSH term search in PubMed.

In the second video, you saw that the search strategy for the "Basic Search" was quite complicated:

((((((((("acupunctural"[All Fields] OR "acupuncture"[MeSH Term]) OR "acupuncture"[All Fields]) OR "acupuncture therapy"[MeSH Term]) OR ("acupuncture"[All Fields] AND "therapy"[All Fields])) OR "acupuncture therapy"[All Fields]) OR "acupuncture's"[All Fields]) OR "acupunctured"[All Fields]) OR "acupunctures"[All Fields]) OR "acupuncturing"[All Fields]) AND (("low back pain"[MeSH Term] OR (("low"[All Fields] AND "back"[All Fields]) AND "pain"[All Fields])) OR "low back pain"[All Fields])

... but by searching ONLY on MeSH terms (thus eliminating the keyword searches), you were able to make it much more concise:

(("Acupuncture Therapy"[MeSH Term]) OR "Acupuncture"[MeSH Term]) AND "Low Back Pain"[MeSH Term]

Notice that all the simultaneous keyword searches have been eliminated in the MeSH term search. This will reduce the possibility of accidentally picking up off-topic (irrelevant) articles simply because they include the keyword somewhere in the database record.

CAVEAT: Keep in mind that although a MeSH term search is more precise, it will not pick up articles that have not yet had the MeSH terms assigned. This usually takes 1-3 weeks, but sometimes longer. The easy way around that is to simply repeat your search at a later date, or set up an automatic email alert, to pick up the newly published articles. Also, a MeSH term search will not pick up articles that are not included in the MEDLINE portion of PubMed. For that reason, if you are conducting a comprehensive search, e.g., for a systematic review, you will probably want to run both a subject term AND a keyword search.

Dana Medical Library, University of Vermont

Burlington, VT, USA

(802) 656-2201

danaref@uvm.edu

Also, the National Library of Medicine has many excellent videos and tutorials on searching PubMed. These can be found by scrolling down to the Find column on PubMed's homepage. This web page provides links for several tutorials, quick guides, and videos.