Annual MeSH Processing (AMP)

NLM performs daily routine maintenance of MEDLINE data. In the fall of each year NLM performs additional maintenance to MEDLINE data, known as Annual MeSH Processing, or AMP. AMP encompasses extensive changes to MEDLINE citations. The primary function of AMP is to update the Medical Subject Headings (MeSH) on existing MEDLINE citations to conform with the upcoming version of MeSH, which is released annually in early December. Changes are made to MeSH descriptors (main headings), qualifiers (subheadings), and Supplementary Concept Records (SCRs), which are standardized names and associated numbers for chemicals, protocols, diseases, organisms, population groups, and anatomical structures that map to MeSH descriptors. Other global changes to MeSH headings may be made during AMP as well.

The nine MeSH update reports listed below detail the changes to MeSH terms that are performed during AMP.  These processing procedures usually start in early December when the annual MeSH update files are released and are targeted for completion by the middle of December.  When AMP activities are complete, the new version of MEDLINE, with the new year's MeSH Headings, is loaded into PubMed, and the regular MEDLINE/PubMed update schedule resumes. At this point PubMed uses the new year's MeSH vocabulary in the MeSH translation tables and the MeSH database.

Each of the MeSH Update Reports are cumulative, containing data for all years, starting from 2023.  Each report contains a Year field, identifying changes to MeSH for that release year.

The resources listed below provide additional information on MeSH and Annual MeSH Processing.

MeSH XML Data Elements

There are nine MeSH Update reports. Seven of the nine reports have filtered views to see changes to Descriptors and/or SCRs only.

The Add Report lists new Descriptors and Supplementary Concept Records (SCRs) that have been added to MeSH for the upcoming new release.  It also includes terms that replace deleted terms, as well as new entry combinations (new precoordinated descriptor heading that replaces an existing descriptor/subheading combination).  There are two filtered views available.

MeSH 2024 Update - Add Report -- All new terms (Descriptors and SCRs)

MeSH 2024 Update - Add Report for Descriptors -- Descriptors-only filtered view

MeSH 2024 Update - Add Report for SCRs -- SCRs-only filtered view

The Preferred Term Update Report lists changes to the Preferred Term of a Descriptor or a Supplementary Concept Record (SCR).  There are two filtered views available. 

MeSH 2024 Update - Preferred Term Update Report -- All terms (Descriptors and SCRs)

MeSH 2024 Update - Preferred Term Update Report for Descriptors -- Descriptors-only filtered view

MeSH 2024 Update - Preferred Term Update Report for SCRs -- SCRs-only filtered view

The Registry Number Update Report lists changes to Registry Numbers on a Descriptor or Supplementary Concept Record (SCR). There are two filtered views available.

MeSH 2024 Update - Registry Number Update Report -- All terms (Descriptors and SCRs)

MeSH 2024 Update - Registry Number Update Report for Descriptors -- Descriptors-only filtered view

MeSH 2024 Update - Registry Number Update Report for SCRs -- SCRs-only filtered view

The Update (All Fields) Report lists each individual modification made to a Descriptor or Supplementary Concept Record (SCR).  More than one field on a term can be modified during YEP, resulting in a term having multiple entries on the list.  There are two filtered views available.    

MeSH 2024 Update - Update (All Fields) Report -- All terms (Descriptors and SCRs)

MeSH 2024 Update - Update (All Fields) Report for Descriptors -- Descriptors-only filtered view

MeSH 2024 Update - Update (All Fields) Report for SCRs -- SCRs-only filtered view

The Replace Report lists Descriptors and Supplementary Concept Records (SCRs) where an existing MeSH term has been replaced by another term.  Note that replacement terms are not necessarily new to the vocabulary; terms are sometimes consolidated under or moved to other existing terms.  There are two filtered views available.

MeSH 2024 Update - Replace Report -- All terms (Descriptors and SCRs)

MeSH 2024 Update - Replace Report for Descriptors -- Descriptors-only filtered view

MeSH 2024 Update - Replace Report for SCRs -- SCRs-only filtered view

The Combine Report lists new Entry Combinations.  These are cases where a new, precoordinated Descriptor has been created to replace an existing Descriptor / Qualifier combination.  The link to the report is below.

MeSH 2024 Update - Combine Report -- New entry combinations

The Split Report lists terms that are replaced by a set of terms, either Descriptors or SCRs, instead of a single term.  The link to the report is below. 

One example of a split is when an SCR for a protein is promoted to a Descriptor representing the generic protein, and new SCRs are created for species-specific forms of the protein that then map to the Descriptor.  Therefore, the original SCR can now be represented more specifically by a list of new choices.  Another example of a split is when a descriptor subconcept is split out as a new descriptor.

MeSH 2024 Update - Split Report -- All terms (Descriptors and SCRs)

The Delete Report lists Descriptors and Supplementary Concept Records (SCRs) that have been removed from MeSH.  There are two filtered views available.

MeSH 2024 Update - Delete Report -- All deleted terms (Descriptors and SCRs)

MeSH 2024 Update - Delete Report for Descriptors -- Descriptors-only filtered view

MeSH 2024 Update - Delete Report for SCRs -- SCRs-only filtered view

The Merge Report describes cases where two or more terms have merged into a single term.  The term(s) being merged into another term become(s) an Entry Term.  Merges can be between Descriptors and Supplementary Concept Records (SCRs), between Descriptors, or between SCRs.  There are two filtered views available. 

MeSH 2024 Update - Merge Report -- All merges

MeSH 2024 Update - Merge Report for Descriptors -- SCR into Descriptor merges; Descriptor into Descriptor merges (For 2023 there are no Descriptor into Descriptor merges)

MeSH 2024 Update - Merge Report for SCRs -- SCR into SCR merges

Data contained within each of the MeSH Update Reports is accessible via application programming interface (API) and are fully documented, including grab-and-go code samples for popular programming languages and data science tools such as jQuery, Python, and SAS.  Links to API documentation are available from the data view of each of the reports (select Export, SODA API, API Docs) and are also linked below.

General API Documentation and developer resources for the Socrata Open Data Platform are available at dev.socrata.com.