LDMEDLINE citations will be added to PubMed soon. [Editor's Note: OLDMEDLINE citations were added to PubMed on September 30, 2003.] This article is divided into three sections:

1. OLDMEDLINE data information (background, years of coverage, data content)
2. PubMed searching information
3. NLM Gateway searching impact.

DATA INFORMATION
Over 1.5 million OLDMEDLINE citations will be added to PubMed. The citations are to articles from international biomedical journals covering the fields of medicine, preclinical sciences, and allied health sciences. The citations were originally printed in hardcopy indexes published from 1953 through 1965.

History
In 1964, NLM^® began using the computerized MEDLARS^® (Medical Literature Analysis and Retrieval System) system as a mechanism for producing Index Medicus^® (IM). In 1971, MEDLARS went online with the introduction of MEDLINE, an interactive searchable database of data from the 1966 Index Medicus forward. The 1964 and 1965 issues of Index Medicus, while available in electronic form, were not included in MEDLINE because of format differences.

In the mid-1990s, NLM was assisted in its effort to provide online access to these older citations by the Deutsches Institut fur Medizinische Dokumentation und Information (DIMDI), the International MEDLARS Center in Germany. DIMDI had tapes of the original data from the 1964 and 1965 Cumulated Index Medicus (CIM), which they had converted and then supplied to NLM to create the OLDMEDLINE file in 1996. NLM then had the citations from the 1960–1963 CIM and the 1953–1959 Current List of Medical Literature (CLML) converted into machine-readable form and added to the OLDMEDLINE file during the past five years.

Data Quality
OLDMEDLINE citations have been created using standards that are different from the data entry standards for MEDLINE records. There are also variations among OLDMEDLINE citations in the data elements (fields) present in the citation, as well as in their format, depending on the original source from which the citations were obtained.

OLDMEDLINE citations lack the accumulated changes and improvements that have been made to data in other NLM files during annual file maintenance. Certain fields may contain outdated or erroneous data and the data are not cosmetically consistent from year to year (e.g., the use of upper/lower case). The data basically reflect the contents of the original printed indexes that were produced under the policies and procedures of the time. The one exception to this is that NLM has identified and updated the journal Title Abbreviation.

Note: In order to load OLDMEDLINE data into PubMed, each citation must be linked to a parent serial record in LocatorPlus. This can be difficult detective work. NLM has made every effort to make the correct links, yet some citations remain unlinked. Therefore, not all citations previously available from OLDMEDLINE will migrate to PubMed immediately. About 7,500 of the 1.5 million will be added in future updates. Users who uncover citations citing the wrong journal should report these corrections to NLM Customer Service.

Data Content
Below is information detailing how the OLDMEDLINE citations differ from MEDLINE citations:

• Abstracts
  OLDMEDLINE citations do not have abstracts.
  
  
• Country (of Publication)
  Present only on citations from 1964–1965 CIM. Citations from 1960–1963 CIM and 1953–1959 CLML have the value "Not Available."
  
  
• Publication Type
  All citations have only "Journal Article." No other Publication Types are used.
  
  
• Issue
  Data are not present for 1960–1965 CIM citations in the separate Issue element. There are citations from 1960–1963 that have both Volume and Issue data in the Volume element. There are citations from 1957 and 1956 that have Issue, but no Volume data.
  
  
• Language
  Citations from 1953–1954 CLML have the value of either "eng" or "und" because the actual foreign language was not specified and is, thus, undetermined. A small number of OLDMEDLINE citations have the language value of "ser" for Serbo-Croatian, which will be resolved to either "scr" for Croatian or "scc" for Serbian.
  
  [Editor's note: The language value of "ser" for Serbo-Croatian has been changed to "und" for undetermined. The former is not a valid value while the latter is. The correct language of Croatian (scr) or Serbian (scc) needs to be addressed at the individual article level (as opposed to the journal level) and the Library does not have resources at this time to undertake the review of over seven thousand citations.]
  
  
• Article Title
  All alphabetic characters in titles from citations in the 1964 and 1965 CIM are in upper case. For all other OLDMEDLINE citations, the first letter of the first word of each "sentence" in the title as well as proper nouns and acronyms (following standard English language usage) are capitalized. Over 28,000 citations have "Not Available" in the article title because they lack English language translations.
  
  
• Citation Subset
  All OLDMEDLINE citations have the Citation Subset value "OM" for OLDMEDLINE. A small number of OLDMEDLINE citations will also have a Citation Subset value of "D" for Dentistry Journals and/or "N" for Nursing Journals.
  
  
• OtherID
  This is an internal NLM element showing the source of the citation. The field occurs only on 1953–1959 data.
  
  
• Other Term
  Other Term contains the original MeSH^® Headings assigned at the time the records were first established prior to 1966. OLDMEDLINE citations were generally assigned fewer subject headings (approximately two to six per citation) and check tags were not used. The original Medical Subject Headings (MeSH) and subheadings assigned to the citations have not been updated, and may not match current MeSH vocabulary. There are no subheadings in citations published in the 1963 through 1965 CIM. Citations from the 1960 through 1962 CIM and the 1953–1959 CLML do contain MeSH Heading/subheading combinations. Subheadings vary from year to year. All headings are flagged as Major Topic, even though that cannot be utilized for searching the data.
  
  Examples:
  
  OT–    *DIABETES MELLITUS
  OT–    *PITUITARY GLAND, ANTERIOR/diseases
  
  Note: There are no data in the MeSH Heading [MH] field. As a result, the subject headings on OLDMEDLINE citations do not relate to current MeSH Tree numbers, and the MeSH "explode" capability that collects indented terms is not functional for these data. There are no check tags.
  
  
• Other Term Owner
  This field identifies the organization that provided the Other Term data. For OLDMEDLINE citations, this field reflects NLM as the owner.

Updates
NLM expects to continue converting citations from its older printed medical indexes to machine-readable form and to add these OLDMEDLINE citations to PubMed as time and resources permit. NLM expects to add 1950–1952 data to PubMed in early 2004. Details for subsequent updates of new records are still to be determined. NLM anticipates a quarterly cycle for revised records.

New Status Tag
A new status tag, PubMed - OLDMEDLINE for Pre1966, identifies citations as OLDMEDLINE:

ADOLPH RJ, BLISS HA.

Body composition in experimental congestive heart failure.

Circ Res. 1962 Jun;10:933-8. No abstract available.

PMID: 13859466 [PubMed - OLDMEDLINE for Pre1966]

New PubMed Subset for OLDMEDLINE Citations
Searches can be limited to OLDMEDLINE using a new subset created for these citations. You may select, OLDMEDLINE for Pre1966, from the Subsets menu in Limits. Alternatively, this subset can be used directly in a search as oldmedline [sb].

Example: (kidney OR kidneys OR renal) AND oldmedline [sb]

Other Term (OT) on OLDMEDLINE Citations
The Other Term field in PubMed contains non-MeSH subject terms. In the case of OLDMEDLINE citations, this field contains the original index terms. These terms are not updated.

Other Terms will display after the OTO field (see below) on the MEDLINE format. These terms are all preceded by an asterisk to indicate a major concept. (Asterisks are for display only. You cannot search Other Terms with a major concept tag.)

This field displays on the MEDLINE format with the OT field tag:

OT - ^*TOXICOLOGIC REPORT

The OT field is searchable with the Text Word [TW] and Other Term [OT] search tags.

Sample search:

experimental lab study [ot]

Other Term Owner (OTO)
The Other Term Owner is an acronym and precedes the Other Term list on the MEDLINE format (see above). It identifies the organization that provided the Other Term data. In the case of OLDMEDLINE citations, this field will identify NLM as the provider:

OTO - NLM

This field is not searchable.

Entrez Date (EDAT)
Normally the Entrez Date (EDAT on the MEDLINE format) is the date the citation first entered PubMed. The Entrez date for OLDMEDLINE citations, however, is created using the date of publication on the citation. This is necessary to prevent older citations from displaying near the top of retrieval as the default display order in PubMed is reverse chronological order of the Entrez date (i.e., last in - first out).

Cubby Stored Searches
Creating the Entrez date using the date of publication on OLDMEDLINE citations also means these citations will not be included in Cubby update retrieval.

Personal Name as Subject (PS)
Many OLDMEDLINE citations reference articles about historical figures. If you want to search for an atypical name, use the following examples as a guide:

james i of england [ps]

louis xiv [ps]

st paul [ps]

More typical names can be searched as in this example:

von gudden b [ps]

Journal Title Abbreviation (TA)
Journal title abbreviations may have been changed from the abbreviation found on the original OLDMEDLINE citation; however, using an old abbreviation will retrieve across all years. NLM's catalog, LocatorPlus will have old title abbreviation data on serial records for OLDMEDLINE journals. As always, full title names can be used for searching in PubMed.

Journal Volume and Issue
Volume and issue data may not have been parsed correctly into the respective fields, or may be missing. For now, be wary or avoid searching specifics in these fields on OLDMEDLINE citations.

Searching Considerations (No Abstracts, No MeSH)
OLDMEDLINE citations do not have fields frequently found on MEDLINE records, including: Abstract, Affiliation, EC/RN Number and Name of Substances [RN], Grant Numbers [GR], and MeSH Terms [MH].

In addition to not having abstracts or MeSH terms, approximately two percent of OLDMEDLINE citations do not have a title. These factors reduce the number of access points for searchers. Also, keep in mind when searching that "limits" that utilize MeSH terms, e.g., age groups, human, etc., will exclude OLDMEDLINE citations. No MeSH also means no capability to explode broad terms to retrieve specific terms. When doing subject searches to include OLDMEDLINE citations consider including variations in vocabulary (e.g., kidney OR kidneys). NLM is investigating whether it will be possible to convert the old index terms to current MeSH vocabulary (as a long term project).

Loansome Doc
All articles cited in PubMed including those in the OLDMEDLINE subset can be ordered using Loansome Doc or other Document Delivery Services available in PubMed.

Are all old citations in PubMed part of the OLDMEDLINE subset?
No. Many older citations have been in PubMed from the beginning and more will be added as we expand our efforts to encourage publishers to provide NLM with older citations electronically. These will not be part of the OLDMEDLINE subset which represents citations appearing in old NLM printed indexes. NLM has much work in store for the future as we incorporate citations from the past into PubMed.

Once OLDMEDLINE citations are added to PubMed, they will no longer reside as a separate collection in the NLM Gateway. The Journal Citations category in the Gateway will contain a single collection of citations that cover 1953 to the present. Users can continue to use the NLM Gateway to search OLDMEDLINE citations which will be retrieved as part of the PubMed hits.

A new search feature in the Gateway will enable the user to limit a search to retrieve only citations from OLDMEDLINE. Click on Limits on the features bar and go to the Subsets pull-down menu. Select OLDMEDLINE for Pre1966 and run the search. This subset Limit will be applicable solely to the Journal Citations category, and the search results will have the status [PubMed - OLDMEDLINE for Pre1966].

Note: Gateway's Order Documents function will continue to enable users to order articles through Loansome Doc for OLDMEDLINE and all citations in PubMed.

For more information on searching, see the Gateway's Help.

By Andrea Demsey,
Annette M. Nahin, and
Susan Von Braunsberg
MEDLARS Management Section

Demsey A, Nahin AM, Von Braunsberg S. OLDMEDLINE Citations Join PubMed^®. NLM Tech Bull. 2003 Sep-Oct;(334):e2.