You may have heard about ‘MeSH terms’ from lecturers or friends who recommend them for improving your search strategy – but, do you know what they are and how to use them? If you’ve never had a formal introduction to MeSH, I’d guess not. And that is where this post comes in. I will explain what MeSH terms are and how we can use them to find the best literature when searching databases.
What is a MeSH term?
Let’s start at the beginning, MeSH stands for Medical Subject Headings and is a set of hierarchically-organised controlled vocabulary around topics in health and medicine. But what does that mean?
It is actually a lot simpler than it sounds. Controlled vocabulary simply means that certain words or terms have been agreed by the community to be used for certain concepts. For example, papers to do with Cancer will be filed under the subject heading ‘Neoplasms’ rather than ‘cancer’ or any other variation – Neoplasms is the term which has been selected as the heading for this type of paper. But how do we know that?
Let’s try this out, go to https://meshb.nlm.nih.gov/search (if you Google ‘MeSH browser’ this will be the first result). The MeSH browser is the easiest place to look up MeSH terms.
If we were trying to determine the MeSH term for cancer, we’d simple type ‘Cancer’ into the search box and hit enter to run the search.
This will locate the relevant term for us and bring up its record as below. You’ll find the MeSH term listed at top of the record in a large font – this is the MeSH term we need to remember / note down. If you want to make sure that the MeSH term that has been returned covers the topic you are interested in, look down the page to the ‘Entry Term(s)’ field. This will list the different concepts covered under the MeSH term and give you a good idea of its scope. If it doesn’t sound right, search again using a different variation of your term.
It is important to note that MeSH terms do not exist in isolation from one another but rather are organised into a hierarchy. So if we look at the screenshot below, we’ll see that ‘Neoplasms’ site beneath the main heading ‘Diseases’ and that there are further layers beneath it if we wanted / were able to be more specific.
The important thing for us, is to know that journal articles that exist in MEDLINE and some other databases will be tagged with the MeSH terms that are relevant to them. By opening up an article’s record in a database as below, you’ll often find a field that lists all the MeSH terms that paper has been tagged with.
Knowing this is extremely helpful as it means we can choose to search databases for papers tagged with relevant MeSH terms instead of, or in combination with, the free text searching we would normally do. This is far more accurate as MeSH terms will have been applied by experts in the field so by searching them we are leveraging an expert’s analysis of the article’s content.
Have a play around with the MeSH browser – there are all sorts of terms in there – they don’t have to be diseases – you’ll find different age groups, genders, treatment settings, and more. See what you can find.
How to use MeSH terms in a database search
This is the really clever part: taking relevant MeSH terms we have identified and using them to search for useful papers in databases. Each search interface has a slightly different process for this so let’s look at the main ones you’ll be using.
In EBSCO you can type your MeSH term(s) directly into a search box in the following format:
You can also use EBSCO’s own MeSH tool to set up MeSH terms in your search. The below video demonstrates how to do this:
In PubMed you can type your MeSH term(s) directly into a search box in the following format and select ‘MeSH terms from the drop-down to the left of the search box:
You can also use PubMed’s index tool to set up MeSH terms in your search. The below video demonstrates how to do this:
You will need to go through Ovid’s Subject Heading tool to include MeSH terms in your search and the following video shows you how to do this:
This should get you started using MeSH to firm up your searches. Of course, this is only a brief introduction so if you would like to know more, talk to your Subject Librarian.