Searching PubMed Like an Expert: Using MeSH Terms

Welcome to the module searching PubMed
like an expert in this part of the module we will look at
a powerful way to search PubMed using MeSH terms. Medical subject
headings which is known as MeSH increase the
precision of your search in a very powerful way by using a single agreed-upon term in a controlled vocabulary to express a
concept no matter what term the authors use in their article. Here is a recently
published article in PubMed. if you scroll down the page and click on publication types and MeSH terms you’ll
see a list of MeSH terms here. Every article that
goes into the PubMed database is analyzed by human beings to discover
what it is actually about. The people who classify these
articles use a long list of agreed-upon vocabulary terms
to describe what the article is about so they don’t just come up with any term to describe the content of the
article– they have to use a term from this list. We can see here that this article is about differential diagnosis and the complications and diagnosis of
HIV infections. it’s also about a few other things– they
usually assign 10 to 15 MeSH terms to it and there are a couple
of other MeSH terms that are of interest: this is a
review article and its furthermore a meta-analysis
under the publication type MeSH term. The asterisks here mean that
this is one of the major concepts of the
article so that’s a great way to narrow down your search so why is it useful to search with MeSH
terms? Well think about this: how many ways can
you express the concept breast cancer? What would an author use when
they were writing about breast cancer in a research article? they might use breast tumors, mammary
cancer, mammary tumors and any number of other terminology might be used so which terms
should you use to search for articles about breast cancer? Well the MeSH term for breast cancer is
actually breast neoplasms. so if an article is about breast cancer
then the indexer at the National Library of Medicine will apply the MeSH term to it: “breast neoplasms.” There are literally thousands of MeSH terms in the National Library of Medicine
system describing all kinds of concepts For a specific population such as
Latinos, the MeSH term for that specific population is Hispanic-Americans. You might be
thinking ahead here and figure: hey if I can find out what the MeSH term is for
my concept that i’m looking for, I can do
a more precise search. And you’d be exactly right. If it’s about that
concept, then the indexers will use the term breast neoplasms so if you use that term
to search, you’ll find all the articles that are
about that concept. Let’s try this out and I’ll show you how that works. Let’s use MeSH to find
articles about ethical issues in bariatric surgery.
Normally if we didn’t know what MeSH term was available for bariatric surgery and
the ethical issues of that, we would just put in bariatric surgery ethical issues and do
a keyword search. I might put an AND in there (between bariatric surgery and ethical issues) I got 76 results and it
looks like number one is not highly relevant and neither is number three and
I bet if I look through this list I would probably find many more that
were not very relevant. How can we do a better search? Let’s use the MeSH method. So what I’m
going to do is divide it up into the most important concepts and the most important concept for me is
bariatric surgery, Now what I’m going to do is instead of
searching PubMed for bariatric surgery I’m going to
search a different database– the MeSH database. I select from the
drop down menu and click search What the system just did is instead
looking for articles about bariatric surgery it wanted to look for MeSH terms that
match my search term. And it found one that exactly
matches. I have the MeSH term here. I have a little
definition for what it’s used for, the year that was introduced to the
database…this is super useful down here I have a list of subheadings that I
could use and look– one exactly matches what I’m looking for. Notice that there are many other
subheadings on this list. some of these might prove very useful to you in
the future like adverse affects. There’s one for diagnosis which is not
listed here; methods, diagnosis, statistics, therapy, and so on. Another
thing I could do is restrict to MeSH major topic. That
means I only want to see articles that this article is mostly about ethics of bariatric surgery. But I’m going to unclick
that and I’m going to click “add to search builder” and then search
PubMed. Now I only have 30 compared to the 76 I had before and these are going to be highly, highly
relevant. Try this on your own with chewing problems in kids with Down syndrome. Do a MeSH
search to do a very precise search for this question. Stop the video
and come back once you’ve tried it. For this information need: chewing
problems in kids with Down syndrome, I basically have
three concepts going on here. I have chewing problems; the age group which
is children & Down syndrome. Here’s how I would do it in
PubMed. First let’s make sure we’re searching MeSH
and let’s put in “chewing problems” Well, how about just “chewing.” Let’s try that. The MeSH term for chewing is mastication Let’s go ahead and add that to our search
builder and let’s do another one. Let’s put in “down
syndrome” OK, that’s the first one (the first MeSH term that shows on the list of results) I have many
different subheadings I could choose from for Down
syndrome but I’m just going to leave it broad and add it to the search builder using
AND. See? Boolean operators! Now I could add “children” but instead of adding “children” I’m going to use that as a filter in my next step Only 11 articles and if I want to narrow
it down a little bit more I’m going to add the age filter which you will learn
about into the next modules. Now I only have seven. How did you do? Did
you get a relatively low number? If you did then you probably did a
pretty good search especially if you used MeSH terms to do it. Here are the reasons why
you want to use MeSH: it increases the precision of your
search and gets articles that are really about your topic. Secondly it allows you
to use subheadings like therapy, genetics, drug effects,
diagnosis, and many more and third it finds
articles regardless of the terminology that the
author uses. Now there’s one catch: using MeSH means that you’re not going
to get the very latest articles that have been published. The
reason for that is because this is a human process and it takes
time for indexers at the National Library of
Medicine to process each Journal issue as it’s published to add index terms to all those
articles. So it does take a few weeks in between
the time that an article shows up in PubMed and when it receives MeSH terms. Those
very recently published articles don’t even have MeSH headings yet to
keep this in mind.

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