Tis the season…for the National Library of Medicine’s (NLM) Annual MeSH Processing for 2024!!

Every November-December brings the much anticipated annual changes to PubMed’s MeSH (Medical Subject Headings) structure for the controlled vocabulary associated with MEDLINE.

Types of MeSH Updates

Some MeSH, subheadings, and supplementary concepts cease to be, some are renamed, new MeSH and subheadings are incorporated, and some MeSH change their location in the MeSH hierarchical tree structure (e.g. a MeSH moves under a different broader heading) or combine with other terms. Some Supplemental Concepts are also upgraded to a MeSH Descriptor status. Below are some of the types of changes and updates made during the Annual MeSH Update.

• New MeSH Descriptors — brand new MeSH Descriptors
• New Supplementary Concepts — brand new terms that currently do not warrant a full MeSH Descriptor
• Changed MeSH Descriptors — MeSH terms that were modified (either by name or hierarchical location), also referred to as the “Preferred Term”
• Upgraded MeSH Descriptors — terms that moved from Supplementary Concepts to MeSH Descriptors
• Combined Terms — either MeSH Descriptors or Supplementary Concepts that were combined with other terms under a single term
• Split Terms — either MeSH Descriptors or Supplementary Concepts that are split to expand the level of description and detail
• Removed Terms — either MeSH Descriptors or Supplementary Concepts that were removed, either due to being combined, upgraded, or renamed

What’s New in 2024

The 2024 MeSH updates includes a variety of important and much-needed updates!

• New MeSH Descriptors
• New Supplementary Concept Records (SCR)
• Changed MeSH Descriptors
• Changed Supplementary Concept Records (SCR)
• Replaced and Combined Terms
• Expanded Terms
• Removed Terms

One of the biggest and most needed expansion in the 2024 update is that of the Psychological Stress concept, with dozens of new MesH Descriptors within the concept of Psychological Stress, including:

• Coping Skills
• Psychological Growth
• Financial Strain
• Psychological Recovery
• School Shooting
• Stress Experience

Impacts on Searching PubMed

MeSH structure changes may affect already saved searches, including My NCBI alerts; for example ceased in 2024 MeSH may be part of your search strategy designed/saved in the previous years and the deleted/ceased to be term will not retrieve any references.

If you have searches saved in your My NCBI account and/or you are getting PubMed e-mail alerts, or if you need to update your Systematic Review based on your previous search strategy, you may want to consult a Research Informationist to ensure your saved searches are not affected by the annual changes in the MeSH terminology. Don’t hesitate to ASK US!

A Note by the National Library of Medicine says: “Typically, NLM does not retroactively re-index MEDLINE citations with new MeSH heading concepts. Therefore, searching PubMed for a new MeSH term tagged with [mh] or [majr] effectively limits retrieval to citations indexed after the term was introduced. Searchers may consult the MeSH database to see the previous indexing terms most likely used for a particular concept before the new MeSH heading was introduced. For terms without previous indexing information, consider the next broader term(s) in the MeSH hierarchy. For more searching guidance, see the on-demand class MeSH Changes and PubMed Searching”.

To Quote or Not To Quote…that is the Struggle

To the average person’s eye quotation marks all look the same, however there are actually two distinct styles of quotation marks: straight and curly (also known as “smart”). The difference is simple, but easily missed.

So what’s the Difference?

Straight quotation marks are single or double vertical lines that frame a word or phrase.

'Straight' or "Straight"

Whereas curly quotation marks are single or double curved lines that change direction depending on if they are framing the beginning or end of the word or phrase. 

‘Curly’ or “Curly”

Visually both of these types of quotation marks function the same way, they signify the beginning and end of a quotation, passage, or phrase. But many publishers prefer curly (also referred to as smart) quotations as they are more pronounced to differentiate the start and end of a passage of text. 

Today, most word processors (i.e. Microsoft Word), automatically change straight quotations to smart quotations as you type. While this automatic feature is meant to make text more legible and in line with publishing standards, when it comes to conducting searches in databases it came make things complicated.

This is especially the case if you are copying and pasting a search strategy from Microsoft Word (or other word processing software), directly into a database. If quotations are automatically changed to curly quotes, it can cause issues with search strategies.

How Literature Databases View Curly (Smart) Quotations

Scholarly databases respond to these curly quotations in one of three ways.

• The search results are identical whether straight or curly quotations were used
• The search results varied depending on whether straight or curly quotations were used
• The search strategy is rejected (error message) due to unsupported characters

This issue can greatly impact searching biomedical literature since curly (smart) quotes are unsupported on the Ovid platform.

Ovid hosts the following biomedical databases:

• MEDLINE
• PsycINFO
• AMED
• JBI
• Embase (for some institutions, not MSK)

IMPORTANT: If curly quotes are put into an Ovid database an error message will be returned.

For more information about literature database platforms and how the respond to quotations:

Phrasing in Reproducible Search Methodology: The Consequences of Straight and Curly Quotation Marks

Barrick, K., & Riegelman, A. 2021. College & Research Libraries, 82(7): 978 

 

How to Disable Smart Quotes in Microsoft Word

For: Word 365, Word 2021, Word 2019, and Word 2016

To err is human, and that includes when we search databases. And while there is always a possibility of typos and errors in searches, the chance of errors increases with the complexity and length of search strategy used.

Most databases, including Pubmed, have mechanisms of alerting a searcher of certain errors found within a search by providing “warnings”, but unfortunately not all typos cause a functional error, and in those instances the database will not provide a warning and the user may end up with unintended search results.

Functional Errors in PubMed

Functional errors in PubMed trigger a warning, as they impede in the function of the database to conduct the search as written.

Quoted phrase not found in phrase index

Not all phrases (string of words you enclose in double quotes) can be found in PubMed due to how PubMed indexes phrases. 

“progenitor cell transplantation”

The easiest solution to this error is remove the double quotes, however this can lead to unintended results if you are not careful. There are several things to keep in mind if you simply remove the quotation marks. 

• If you remove double quotes from a phrase not found, but are using a specific field code, the search would be broadened by implying that there are Boolean operator AND in between each word, but the field code prevents PubMed from automatically mapping.  

“progenitor cell transplantation”[tiab] → progenitor cell transplantation[tiab]

• If you remove double quotes from a phrase not found, but are not using any field codes at the end of your phrase, the automatic translation by PubMed would become much broader than intended as it will add additional mapping to MeSH terms and word variations for each separate term.

“progenitor cell transplantation” → progenitor AND cell AND transplantation

PubMed recommends using proximity searching to fix this error. Proximity searching is a newer feature in PubMed that allows the user to control how close terms are to one another. In the example below it would only retrieve results in which all 3 terms were found within 3 words of one another.

“progenitor cell transplantation”[tiab:~3]

The last and most extreme solution to this functional error is to switch to a database that does not restrict phrase searching, such as Embase.

The asterisk in your search was ignored

If you are using an asterisk as a wildcard (truncation) in a search strategy, you must use 4 or more characters.

The easiest way to fix this error is simply lengthen the root word to at least 4 characters to truncate and include all possible endings.

The following term(s) were ignored:

This error is usually caused by a typo where something in your search is unbalanced or unpaired, including parentheses, quotation marks, and duplicate boolean operators. 

If you are unable to quickly locate where the issue is, go to Advanced Search and click on the ! under details. This will expand out your entire search strategy and highlight where the error is located.

Common Search Typos

Since these are typos, they often do not trigger a warning within PubMed so it’s important to carefully check your search strategy to make sure everything is correct.

Boolean Operators

Boolean operators (AND, OR, NOT) must be fully capitalized. If they are not capitalized or only the first letter is capitalized, the search translates it as a term and not a Boolean operator, meaning Or would find the word Or in the record but would not OR together two terms. 

If a Boolean operator is omitted PubMed will automatically insert the AND operator. Since AND and OR produce significantly different results, an unintended AND where the search needs an OR would cause a serious alteration in the results, but since it is a legitimate search technique, there would be no warning from PubMed.