PubMed - MEDLINE

The reason for the difference in total citations? In addition to MEDLINE, PubMed also offers access to:

• OLDMEDLINE for pre-1966 citations. (~2 million citations as of 2010)
• Citations out-of-scope (e.g., covering plate tectonics or astrophysics) from some journals, primarily general science and general chemistry journals, for which the life sciences articles are indexed for MEDLINE
• In-process citations with records for articles before indexed with MeSH, added to MEDLINE or converted to out-of-scope status
• Citations that precede when a journal was selected for MEDLINE indexing (when supplied electronically by the publisher)
• Some life science journals that submit full text to PubMed Central and may not have been recommended for inclusion in MEDLINE although they have undergone a review by NLM, and some physics journals that were part of a prototype PubMed in the early 1990s

In addition, PubMed points to articles that are open-access and/or freely-available on the Web. PubMed is one of a number of search engines to access MEDLINE. The National Library of Medicine leases MEDLINE information to a number of private vendors such as OVID Technologies, EBSCO and SilverPlatter. It must be said that MEDLINE forms the core of PubMed, and an understanding of the MeSH controlled vocabulary is essential for effective searching of the database.

Canadian context

The question about the amount of Canadian content in PubMed is an important one. True, PubMed does have an American bias, but this may be because of several factors related to where journals are published and where clinicians work. However, to determine how much Canadian content resides in a database, searchers should consider that there are Medical Subject Headings (MeSH) that permit the application of terms for all provinces and territories. Use Canada or Canadian as keywords, for example. Specific health issues regarding Canada's health care systems are not well-addressed by PubMed and there is an inherent American bias (as mentioned) in the controlled vocabulary. Geographic subdivisions - Canada, and the provinces - are recommended for health issues pertaining to specific regions of the country ie. HIV infection in the downtown Eastside of Vancouver, try "British Columbia" or "Canada"[MeSH] and "downtown eastside" (or its variants).

See also

• Top Biomedical Texts 2010, Print & Online
• Medline & PubMed
• Expert searching
• Filters (ie. hedges)
• Hand-searching
• Nucleotide searching
• Point of care decision-making tools - Overview

References

• Darmoni SJ, Neveol A, Renard JM, Gehanno JF, Soualmia LF, Dahamna B, et al. A MEDLINE categorization algorithm. BMC Med Inform Decis Mak. 2006;6:7.
• Eagledawg blog. PubMed tutorials. January 7th, 2010.
• Greenberg SJ, Gallagher PE. The great contribution: Index Medicus, Index-Catalogue, and IndexCat. J Med Libr Assoc. 2009 April; 97(2): 108–113.
• Hoogendam A, Stalenhoef AFH, de Vries Robbé PF. Answers to questions posed during daily patient care are more likely to be answered by UpToDate than PubMed. JMIR. 2008 Oct–Dec; 10(4): e29.
• Katcher BS. MEDLINE: a guide to effective searching in PubMed and other interfaces. 2006 pp. 136. ISBN 0967344514.
• Knecht LS. Canadian Institutes of Health Research: A New Granting Organization for MEDLINE/PubMed. NLM Tech Bull. 2010 Jan-Feb;(372):e2. (http://www.nlm.nih.gov/bsd/grant_acronym.html)
• Muin M, Fontelo P. Technical development of PubMed Interact: an improved interface for MEDLINE/PubMed searches. BMC Med Inform Decis Mak. 2006; 6: 36.
• MEDLINE®/PubMed® Resources Guide
• PubMed Online Tutorials
• PubMed Factsheet
• Tuttle BD, Von Isenburg M, Schardt C, Powers A. PubMed instruction for medical students: searching for a better way. Med Ref Serv Q. 2009 Jul;28(3):199-210.