Category Archives: About Resources

2025 MeSH Update and PubMed Year-End Activities

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At the end of each year, the National Library of Medicine (NLM) produces their annual updates to PubMed’s MeSH (Medical Subject Headings). These changes are made at every level of the MeSH infrastructure, including descriptors (headings or terms), qualifiers (subheadings), and supplementary concepts, and are made in response to changes in scientific discovery, taxonomy, ethical considerations, and published literature. The National Library of Medicine describes the necessity of these changes as this: “In biomedicine and related areas, new concepts are constantly emerging, old concepts are in a state of flux and terminology and usage are modified accordingly. To accommodate these changes, descriptors must be added to, changed or deleted from MeSH with adjustments in the related hierarchies, the Tree Structures.”

Types of MeSH Changes

  • Added Terms — brand new terms added, either as MeSH headings or Supplementary Concepts that currently do not warrant a full heading
  • Modified Terms — MeSH concepts that were changed (either name or hierarchical location), also referred to the the “Preferred Term“
  • Replaced Terms — Descriptors or Supplementary concept terms are replaced by another term; this can include Supplementary Concepts upgraded to Descriptors as well as merged terms
  • Merged Terms — Multiple Descriptor or Supplementary concept terms combined under a single concept term
  • Combined Terms — Descriptor and Qualifier (subheading) combination made into a new separate concept
  • Deleted Terms — Descriptor or Supplementary concept terms removed, due to either being combined, upgraded, or renamed

What’s New in 2025

Artificial Intelligence

The 2025 Annual MeSH Update includes a variety of important and much-needed changes. One of the biggest and most needed expansions in the 2025 update is to the Artificial Intelligence concept, including dozens of new MeSH Descriptors found within the broader concept, including:

Publication types

Several changes were made to publication types for MeSH 2025, including two new publication types:

Note: The NLM has made an exception to their general rule of not retroactively indexing; so just as they did in 2019 when “Systematic Reviews” became a separate publication type, citations will be retroactively updated to reflect these two new publication types.

The Network Meta-Analysis publication type was previously a Descriptor (MeSH Heading); thus for existing citations, the Descriptor term (“Network Meta-Analysis”[MeSH]) will be replaced with either the “Network Meta-Analysis”[Publication Type] OR “Network Meta-Analysis as Topic”[Mesh] as appropriate. This is an important change, as it extends the scope of indexing the publication type back to the introduction of the original term in 2017.

The “Scoping Review”[Publication Type] will replace either the “Review”[Publication Type] or “Systematic Review”[Publication Type] on appropriate citations extending back to 2020, the first year this term appears in MEDLINE. Additionally, “Scoping Review as Topic”[Mesh] has been expanded from the “Review as a Topic”[Mesh] term.

Additionally, NLM will discontinue indexing following Publication Type terms:

Note: As with previously discontinued Publication Types, which include “Government Publication,” “Newspaper Article,” “Overall,” and “Scientific Integrity Review,” these Publication Types will continue to exist in MeSH, appear on existing citations, and be searchable in PubMed. However, they will no longer be applied to new citations.

How Does this Impact Searching?

Since there are so many changes to MeSH terms and structure, if you save search strategies or search alerts, or want to rerun a search that was previously conducted (such as from a systematic review), these changes may impact if and how your search strategy functions. Below are some steps to take to ensure that your search strategy is not only viable but also the best reflection of the current database.

  1. Check search viability — Run your search in PubMed and go to Advanced Search and check if there are issues being highlighted in the Details section. Terms that were removed or modified (name changed, upgraded, merged, etc.) will likely be in red. If your search is suddenly retrieving no results, this also could be the cause.
  2. Identify relevant new terms — Refer to the New MeSH Descriptors for 2025 list to see if there are any relevant terms that were added for 2025 that may make your search strategy more robust or specific.
  3. Identify replaced terms — Refer to the MeSH 2025 – Replace Report to identify any terms that were replaced by another term, upgraded to Descriptors, or consolidated with another term.
  4. Review publication types — Refer to the Annual MeSH Processing for 2025 NLM Bulletin for changes to publication types

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!

Important Note from NLM Regarding Reindexing

Typically, the 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. or more searching guidance, see the on-demand class MeSH Changes and PubMed Searching.

NIH Common Data Element (CDE) Repository

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The practice of re-using a research survey or measurement instrument (while respecting copyright and giving proper attribution) – especially a validated one – is a common one that everyone  (especially research funders) can agree makes research more efficient and cost-effective.  For example, anyone familiar with the REDCap electronic data capture tool is likely aware of the REDCap Shared Library that “is a repository for REDCap data collection instruments and forms that can be downloaded and used by researchers at REDCap partner institutions“. Even NIH survey materials like the NIH’s All of US Programs are available for download from there.



Even though a data collection instrument in its entirety often cannot satisfy the unique needs of an original research project, it is still useful to collect the commonly-used individual data elements/variables of an instrument in a consistent and standardized way (that other researchers are also adopting in their own projects) because this makes the data collected for diverse studies more interoperable (i.e. increases the potential for this information to be shared/combined in future research projects).

And “the use of particular standards to enable interoperability of datasets” is an important component of the 2023 NIH Data Management and Sharing Policy, which aligns with the FAIR data principles – see: 

“NIH has issued the Data Management and Sharing (DMS) policy (effective January 25, 2023) to promote the sharing of scientific data. Sharing scientific data accelerates biomedical research discovery, in part, by enabling validation of research results, providing accessibility to high-value datasets, and promoting data reuse for future research studies.“

This brings us to the NIH Common Data Element (CDE) Repository, which is “hosted and maintained by the National Library of Medicine (NLM)”. To encourage the use of Common Data Elements (CDEs) and make it easier for researchers to identify CDEs that might be useful for their research project, NLM has created this searchable repository/catalog that users can freely access online.

Users can search for individual CDEs or multiple CDEs that are curated into Forms. The search can also be limited to NIH-Endorsed CDEs, which are CDEs that have “been reviewed and approved by an expert panel, and meet established criteria”. Furthermore, “NIH-recognized bodies (institutes, research initiatives, etc.) may submit CDEs to the NIH CDE Governance Committee for consideration for endorsement” via the Repository’s homepage – see: 

NIH Common Data Element (CDE) Repository – https://cde.nlm.nih.gov/home

From the NIH CDE Repository User Guide: https://cde.nlm.nih.gov/guides

“The NIH CDE Repository uses the Unified Medical Language System (UMLS) Terminology Service (UTS) Sign on Service which lets you set up an account and sign in using your NIH credentials, your account with a research organization, or a personal account such as Google, Microsoft, or Login.gov.

A user account is not required to browse the NIH CDE Repository, but when you are signed in, you will have expanded access to features. User account holders can create Boards and save CDEs and Forms to them, remember your preferences on all your devices, and if approved, become a curator, and view/manage your organization’s content. Users with NIH credentials can choose to see CDEs of any registration status – including previewing draft CDEs that have not yet been published.”

NLM also offers these CDE training options where you can learn more:

Questions? Ask Us at the MSK Library!

Interactive Tools for Exploring Language Use

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As per the U.S. Census (see: What Languages Do We Speak in the United States?):

“The number of people in the United States who spoke a language other than English at home nearly tripled from 23.1 million (about 1 in 10) in 1980 to 67.8 million (almost 1 in 5) in 2019, according to a recent U.S. Census Bureau report.”

Thanks to some interactive tools developed using data from the U.S. Census Bureau’s American Community Survey, it has never been easier to explore what languages are being spoken in different geographic areas of the United States. Below are some examples of some user-friendly, freely available tools that you may wish to check out.

  1. U.S Census Data Website

Among the various data profiles, tables and maps, tools and visualization options, is the interactive People That Speak English Less Than “Very Well” in the United States Interactive Map that can be queried using state and county information.

This data is available because the U.S. Census asks “about whether a person speaks a language other than English at home, what language he/she speaks, and how well he/she speaks English to create statistics about language and the ability to speak English”.

For example, searching for New York and Nassau County shows where in that area people with Limited English Proficiency (LEP) may live:

      2. Languages Spoken by People who have Limited English Ability
         (Web Map by Urban Observatory by Esri)

This is another tool that “shows the predominant language(s) spoken by people who have limited English speaking ability” using ArcGIS to again visualize the “American Community Survey data from the US Census Bureau by state, county, and tract”. This map allows you to visualize the data about what languages are being spoken by LEP individuals living around a particular street address or place.

For example, searching for “1101 Hempstead Tpke, Uniondale, NY, 11553, USA” returns:

     3. State Immigration Data Profiles

To get a better understanding of where foreign-born individuals are migrating from, their English proficiency and language spoken at home, the Migration Policy Institute also used U.S. Census data to create an interactive migration data hub tool that allows users to explore state immigration data profiles. You can click on the state of interest to view state-level “facts about immigrants to the U.S.”

Questions?  Ask Us at the MSK Library!