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Table of Contents: 2018 NOVEMBER–DECEMBER No. 425

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MEDLINE Data Changes—2019

Tybaert S. MEDLINE Data Changes—2019. NLM Tech Bull. 2018 Nov-Dec;(425):e4a.

2018 November 30 [posted]

This article collects the notable data changes made to MEDLINE during the National Library of Medicine (NLM) annual maintenance known as Year-End Processing (YEP) for 2019:


MeSH Vocabulary Updated for 2019

The MeSH Browser currently points to the 2019 MeSH vocabulary with a link to the 2018 MeSH vocabulary. Searchers should consult the Browser to find MeSH headings of interest and their relationships to other headings. The Browser contains MeSH heading records that may include Scope Notes, Annotations, Entry Terms, History Notes, Allowable Qualifiers (Subheadings), Previous Indexing, and other information. It also includes Subheading records and Supplementary Concept Records (SCRs) for substances and diseases that are not MeSH headings.

You can download 2019 MeSH from links on the NLM Data Distribution page for MeSH Data.

For highlights about 2019 MeSH, see the forthcoming article What's New for 2019 MeSH.

The PubMed MeSH database and translation tables will be updated to reflect 2019 MeSH by the middle of December when YEP activities are complete and the newly maintained MEDLINE data are available in PubMed.

Updated MeSH in MEDLINE Citations

MEDLINE records with updated MeSH are anticipated to be in PubMed by mid-December 2018. See "Modifying a Saved Search Strategy" for details on revising My NCBI saved searches.

Changes to MeSH Headings

For 2019, 73 MeSH headings were either changed or deleted and replaced with more up-to-date terminology. During YEP, NLM updates these MeSH headings on MEDLINE citations.

New MeSH Headings and Concepts

402 new MeSH Headings, plus 20 new Publication Types, were added to MeSH in 2019.

A complete list of the new 2019 MeSH headings is available in PDF format, see New Headings with Scope Notes, Annotations and Tree Locations.

Typically, NLM does not retrospectively 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. PubMed Automatic Term Mapping (ATM) expands an untagged subject search to include both MeSH Terms and All Fields index terms and may retrieve relevant citations indexed before the introduction of a new MeSH term. Searchers may consult the MeSH Browser or the MeSH database to see the previous indexing terms most likely used for a particular concept before the new MeSH Heading was introduced.

Exception for 2019: The new publication type Systematic Review (see below) will be added to appropriate existing MEDLINE citations. NLM made the decision to do this re-indexing based on the importance of providing a mechanism to retrieve all MEDLINE citations to articles that are systematic reviews.

Changes of particular interest to searchers:

MeSH Publication Types

Twenty new publication types are available for 2019.

Four new publication types will be used for MEDLINE indexing.

Indexing Policy: In 2016, NIH narrowed the definition of a Clinical Trial to specify that it be used for humans only going forward. For that reason, NLM added additional MeSH clinical trial terminology to address animal trials. Note that the publication type Clinical Trial Protocol, however, can be used for both human and animal clinical trials that are being planned. Indexers will coordinate this term with either Humans or Animals.

Sixteen new publication types will be used by NLM Cataloging only:

Seven publication type strings were changed for publication types that are used for MEDLINE Indexing:

Fifty-four publication type strings were changed for publication types that are used for Cataloging only.

Three MeSH headings were changed to publication types for 2019. These publication types are used by Cataloging only. New "as Topic" MeSH headings were not created.

Three new "as Topic" MeSH headings will be used for MEDLINE indexing. Their corresponding publication types will used for MEDLINE indexing as well:

Lastly, five new "as Topic" MeSH headings will be used for MEDLINE indexing. Their corresponding publication types will not be used for MEDLINE indexing:

MeSH Qualifier (Subheading) Changes

For 2019 MeSH, NLM has continued its project of reviewing subheadings in order to improve indexing consistency and efficiency and to make MEDLINE searching easier and more straightforward.

1. One subheading was deleted and replaced by a new MeSH heading.

  • Deleted Subheading: /manpower

The new MeSH heading Workforce was created to replace /manpower. Note that the existing MeSH heading Health Manpower was changed to Health Workforce, which is a child to Workforce.

MEDLINE Citation Maintenance: The subheading /manpower was deleted and an additional action replaced /manpower with the new MeSH heading Workforce on MEDLINE citations. Note that NLM only replaced /manpower on those citations that were not indexed already with Health Workforce.

2. In addition, two subheadings were deleted and replaced with existing subheadings.

Four new MeSH headings were added related to these changes:

MeSH Tree Changes

See New Headings by major Tree Category for 2019 (PDF format).

Or see Descriptor Tree with Headings (text format) for a complete list of the MeSH heading tree hierarchy.

Other changes of particular interest include:

Two MeSH concepts merged into one:

  • Rhamnus merged into Frangula. The preferred string for Frangula then changed to Rhamnus.
  • Salicaceae merged into Flacourtiaceae. The preferred string for Flacourtiaceae then changed to Salicaceae.

Special MeSH Projects

Several special projects were undertaken by MeSH staff that resulted in the following new 2019 MeSH headings:

Neoplasm Terms:

Data Terms:

Drug Combination Terms:

Dietary Protein Terms:

Behavior Terms:

Person Term:

Do Not Confuse:

Other Changes:

In addition to changes and deletions of MeSH terms on MEDLINE citations, YEP includes other adjustments to reflect 2019 MeSH vocabulary and enhance search retrieval. These follow-on adjustments are largely to add additional MeSH headings or Supplementary Concept Record Names to citations in order to help searchers refine retrieval. In some cases, the changes clarify areas where a single concept existed before but is now represented by two or more specific concepts.

  • The SCR ROB was deleted from MeSH in 2019 because it had multiple meanings.

Entry Combination Revisions

This year during YEP, NLM will again retrospectively replace certain MeSH heading/subheading combinations, known as Entry Combinations, with the new pre-coordinated MeSH heading. If you get no retrieval for a MeSH heading/subheading combination check the heading in the 2019 MeSH Browser to see if the Entry Combination information indicates a different term.

There are seven new Entry Combinations for 2019.


Previous MeSH Heading/Subheading
(Entry Combination)
Replaced-by Heading for 2019
Allogeneic Cells/transplantationTransplantation, Homologous
Enzymes/therapeutic useEnzyme Therapy
Epidermis/cytologyEpidermal Cells
Heavy Ions/therapeutic useHeavy Ion Radiotherapy
Intestines/metabolismIntestinal Mucosa/metabolism
Intestines/secretionIntestinal Mucosa/metabolism
Jaw/surgeryOrthognathic Surgical Procedures
Nose/metabolismNasal Mucosa/metabolism
Nose/secretionNasal Mucosa/metabolism
Pharmacy/historyHistory of Pharmacy
Piperazines/analogs & derivativesPiperazine
Protons/therapeutic useProton Therapy
Sodium-Glucose Transporter 2/antagonists & inhibitorsSodium-Glucose Transporter 2 Inhibitors
Stomach/metabolismGastric Mucosa/metabolism
Stomach/secretionGastric Mucosa/metabolism

Other News:

Data Distribution Notes

DTD Changes: On September 13, 2018, NLM announced the release of the 2019 PubMed DTD.

There are several changes from the current 2018 PubMed DTD:

  • The 2019 DTD includes the addition of <ReferenceList>, <Reference>, and <Citation> elements. The cites data, currently found in <CommentsCorrections RefType="Cites">, will be moved to the new <ReferenceList> elements when the 2019 Baseline is released.
  • The <CitationString> element will be removed from the <BookDocument> element.
    • Four new valid values have been added to the RefType attribute of the <CommentsCorrections> element:
    • CorrectedandRepublishedIn
    • CorrectedandRepublishedFrom
    • RetractedandRepublishedIn
    • RetractedandRepublishedFrom
  • A new valid value "plain-language-summary" has been added to the Type attribute of the <OtherAbstract> element to identify Plain Language Summaries.

Additional information and announcements can be found at Download MEDLINE/PubMed Data.


  • Other changes maintained during Year-End Processing. Roughly 2 million citations will export because they will have gotten the Indexing Method attribute "Curated" or "Automated". These include citation which had been indexed for OLDMEDLINE and a smaller number of other citations.

New Databank Source

During 2018 NLM added to the list of Databank Sources that may be carried in MEDLINE citations. The Peruvian Clinical Trial Registry (REPEC), which is one of the WHO Clinical Trial Primary Registries, was added.

By Sara Tybaert
MEDLARS Management Section

NLM Technical Bulletin National Library of Medicine National Institutes of Health