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 Baseline  Created  # Files  # Citations   # MEDLINE 
2002 Approx. November 21, 2001 379 11,299,108 11,289,156
2003 November 1-4, 2002 396 11,847,524 11,821,515
2004 November 14-18, 2003 417 12,421,396 12,375,544
2005 November 20, 2004 500 14,792,864 12,957,019
2006 November 18 & 19, 2005 516 15,433,668 13,554,741
2007 November 17 & 18, 2006 538 16,120,074 15,435,706
2008 November 16 & 17, 2007 563 16,880,015 16,209,581
2009 November 21 & 22, 2008 593 17,764,826 17,031,816
2010 November 20, 2009 617 18,502,916 17,733,905
2011 November 19, 2010 653 19,569,568 18,433,660
2012 November 18, 2011 684 20,494,848 19,252,788
2013 November 15 & 16, 2012 717 21,508,439 20,063,487
2014 November 21, 2013 746 22,376,811 20,785,621
2015 November 24, 2014 779 23,343,329 21,694,483
2016 November 20, 2015 812 24,358,442 22,775,609
2017 December 13, 2016 892 26,759,399 23,621,675
List of Available Baselines
The baselines also contain citations that are not MEDLINE. All of the baselines we have stored (2002 on) contain "Out-of-scope" citations which were renamed to "PubMed-not-MEDLINE" starting with the 2004 MEDLINE/PubMed Baseline. The PubMed-not-MEDLINE status refers to citations that reside in PubMed from journals included in MEDLINE and have undergone quality review but are not assigned MeSH headings because the cited item is not in scope for MEDLINE either by topic or by date of publication. Citations in the Out-of-scope or PubMed-not-MEDLINE status make up a very small percentage of the total number of citations contained in the baselines (For example, 0.51% or 75,271 records in the 2005 baseline and 1.8% or 323,919 records in the 2009 baseline).

Starting with the 2005 MEDLINE/PubMed Baseline, OLDMEDLINE citations are also included in the baselines. The OLDMEDLINE citations make up approximately 11% of the total number of baseline citations. The OLDMEDLINE citations are from international biomedical journals covering the fields of medicine, preclinical sciences, and allied health sciences. The citations were originally printed in hardcopy indexes published prior to 1966. For additional information, please refer to the following URL:
https://www.nlm.nih.gov/databases/databases_oldmedline.html.

In the 2005 baseline the subject indexing from the OLDMEDLINE citations were stored solely in the "Other Term" (or "OT") tagged fields and not the MeSH Terms (or MH) tagged fields. This means that searching the 2005 baseline from our MBR Query Tool via the MH field does not include any OLDMEDLINE citations. The only way to include OLDMEDLINE records in the 2005 baseline is to do a timeframe query without specifying any field specific search criteria. Beginning with the 2006 baseline, Other Terms are starting to be mapped to current MeSH Terms so that searching via the MH field may retrieve some OLDMEDLINE records, but, not necessarily the complete set of possibilities.

Starting with the 2007 MEDLINE/PubMed Baseline, on records where all the OLDMEDLINE terms are converted to MeSH Headings, the citation status changes to MEDLINE. You need to rely on the <CitationSubset> element in the XML files and the "SB" field in the MEDLINE ASCII files to determine if a citation is in the OLDMEDLINE subset. For example,

PMID: 14771459
In the XML file: <CitationSubset>OM</CitationSubset>
In the MEDLINE ASCII file: SB - OM
OLDMEDLINE Determination Example

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Last Modified: May 30, 2017   
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