MEDLINE currently contains over 16 million references to journal articles from the 1950s onwards. Currently 5,200 journals in 37 languages are indexed for MEDLINE:
o www.nlm.nih.gov/pubs/factsheets/medline.html
PubMed provides access to a free version of MEDLINE that also includes up-to-date citations not yet indexed for MEDLINE:
o www.nlm.nih.gov/pubs/factsheets/pubmed.html
Additionally, PubMed includes records from journals that are not indexed for MEDLINE and records considered ‘out-of-scope’ from journals that are partially indexed for MEDLINE. For further information about the differences between MEDLINE and PubMed see:
o www.nlm.nih.gov/pubs/factsheets/dif_med_pub.html
MEDLINE is also available on subscription from a number of online database vendors, such as Ovid. Access is usually free to members of the institutions paying the subscriptions, e.g. hospitals and universities.
The US National Library of Medicine (NLM) has developed the NLM Gateway, which allows users to search MEDLINE or PubMed together with other NLM resources simultaneously such as the Health Services Research Projects database (HSRProj), Meeting Abstracts and the TOXLINE Subset for toxicology citations.
EMBASE currently contains over 11 million records from 1974 onwards. Currently 4,800 journals are indexed for EMBASE in 30 languages.
o www.info.embase.com/embase_suite/about/brochures/embase_fs.pdf
EMBASE.com is Elsevier’s own version of EMBASE that, in addition to the 12 million EMBASE records from 1974 onwards, also includes over 7 million unique records from MEDLINE from 1966 to date, thus allowing both databases to be searched simultaneously.
o www.info.embase.com/embase_com/about/index.shtml
In 2007, Elsevier launched EMBASE Classic which now provides access to records digitized from the Excerpta Medica print journals (the original print indexes from which EMBASE was created) from 1947 to 1973.
o www.info.embaseclassic.com/pdfs/factsheet.pdf
EMBASE is only available by subscription. Authors should check if their CRG has access and, if not, whether it is available through their local institution’s library.
For guidance on how to search MEDLINE and EMBASE for reports of trials, see Sections 6.3.3.2, 6.4.11.1 and 6.4.11.2.
Of the 4,800 journals indexed in EMBASE, 1,800 are not indexed in MEDLINE. Similarly, of the 5,200 journals indexed in MEDLINE, 1,800 are not indexed in EMBASE.
o www.info.embase.com/embase_suite/about/brochures/embase_fs.pdf
The actual degree of reference overlap varies widely according to the topic but studies comparing searches of the two databases have generally concluded that a comprehensive search requires that both databases be searched (Suarez-Almazor 2000). Although MEDLINE and EMBASE searches tend not to identify the same sets of references, they have been found to return similar numbers of relevant references.