Classification & indexing in health libraries

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  • Updated.jpg This entry is out of date and will not be updated, July 2017


See also Medical Subject Headings (MeSH) | National Library of Medicine (NLM) Classification Scheme | Resource Description and Access (RDA)

Classification and indexing are two important technical services functions with those libraries that offer health and medical information. This includes public libraries as well as academic health libraries. Since the early 1940s, medical libraries have used the National Library of Medicine classification scheme to organize their collections but prior to that a number of other classification systems were used such as the Library of Congress "Rs" and the Dewey Decimal 600s. The NLMC is a faceted scheme that can be traced back to the 1880s and the work of bibliographer and medical librarian John Shaw Billings. Interestingly, this formative period in library science saw Herbert Putnam and Charles A. Cutter's work on the Library of Congress classification system and the Belgians Paul Otlet and Henri de Lafontaine's work on the Universal Decimal Classification. NLMC's Ws - Medicine & related subjects has been vacant in the Library of Congress scheme since 1897. The NLMC is a much more detailed scheme than just about any other currently used in medical libraries. Several American health librarians such as Mary L. Marshall and Frank B. Rogers developed the NLM scheme in the 1940s and 1950s. The LOC and NLM systems are designed to work together to ensure optimal resource discovery (or findability), browsing and seamless access to pre-clinical and clinical materials in health libraries. (See also Melvil Dewey).

A number of health and patient libraries in the United States use the Planetree classification system as it reflects the level of specificity needed to classify those collections.

"Barnard" classification of books

The "Barnard" classification of books was introduced in the United Kingdom in 1936 by Cyril Cuthbert Barnard (1894-1959) who was the librarian at the London School of Hygiene and Tropical Medicine. The Barnard classification is still used to this day in some British and European tropical medicine and veterinary medicine libraries. The Barnard classification of books was published as a second edition in 1955 by ΗΚ Lewis; it was based on the library of the London School of Hygiene and Tropical Medicine; but, in preparation of the new edition, the author was aware that other medical libraries were using the scheme and changes were introduced to accommodate the needs of other, more general, medical libraries. The third edition was modified and will consist of additions and amendments and will not involve the extensive re-location of subjects necessary for the second edition. The compilation of the scheme was based on literary warrant; that is to say, the author studied the existing literature in appropriate libraries as also catalogues such as the Index-Catalogue of the Surgeon-General's Library, and the NLM. The author tested, and modified, the second edition by re-classifying the World Health Organization library in Geneva. The original basis of the scheme could be summarized as 'diseases and conditions having a similar causation are usefully studied together and clinically treated 'together'. Hence the primary arrangement of subjects is etiological.

NLM & LOC plus MeSH

The NLM classification scheme, with the NLM Medical Subject Headings (MeSH) thesaurus, is a means to organize and describe materials held in health libraries. These major tools help health librarians and their users move seamlessly from biomedical databases (i.e. journal collections) to library catalogues (i.e. print/digital items) and to locate information. Several international classification systems permit the assignment of alpha-numeric (or numeric alone) call numbers to bring out medical facets in various intellectual works, notably the Dewey Decimal Classification and the Library of Congress Classification. Indexing of articles or subject analysis in biomedicine is generally accomplished using the NLM's medical subject headings (MeSH) thesaurus. However, the LC Subject Headings have been used by some health libraries to describe monographs, audiovisual materials and realia of various kinds. A number of controlled vocabularies are used in nursing (CINAHL headings) and pharmacy (EMTREE headings).

Canadian context

Most academic health and hospital libraries in Canada make simultaneous use of the NLM and Library of Congress systems. Consequently, the QS-QZs and Ws (NLM) are used in conjunction the pre-clinical Q-QRs (LOC) categories. Some Canadian consumer health and patient libraries use the Planetree classification system as it reflects the level of specificity needed to classify those collections. (See InspireHealth Vancouver catalogue). Some Canadian health libraries such as the Canada Institute for Scientific and Technical Information (CISTI) and the University of Alberta Health Libraries have opted to use LOC instead of the NLM system. The difference is that the LOC system places medicine in the Rs. In a recent study, it was revealed that 75% of academic health sciences libraries use the NLM classification system and 95% use MeSH (Medical Subject Headings). General libraries at the same institutions overwhelmingly use the systems developed by the Library of Congress. The most compelling reason for the use of NLM systems is that they are considered the most appropriate for medical collections and facilitate accurate access to and description of materials.

The impact of the web and digital content

With the rise of social tagging in web 2.0 and the semantic web, as well as other web trends such as Open Access, the question arises whether the NLM classification and subject analysis systems are flexible and robust enough to deal with changes in online access to biomedical information. There is considerable room for debate on this point. Some medical websites have used the Universal Decimal Classification (UDC) to organize browsable categories at their sites (see Intute) although the NLM system is generally viewed by health librarians as the better system.

RDA & health libraries

One important factor in the future of classification in health libraries is the third edition of AACR2 called Resource description and access (RDA) which attempts to account for linking to digital access and objects on the web from within health library catalogues. (See NLM RDA page). For library professionals who describe information resources, the future challenge is to create metadata that will meet the needs of users while also making it possible to search and display content on library OPACs. To assist in these important functions, RDA is one building block in creating better catalogues and resource discovery systems. The shift to RDA requires a fundamental re-thinking of how we catalogue and describe resources and provide access to them.

Technical benefits: of RDA are:

  • RDA is compatible with several encoding schemas, such as MODS, Dublin Core, ONIX and MARC
  • blended conceptual models of FRBR (functional requirements for bibliographic data) and FRAD (functional requirements for authority data) to help users find information more easily
  • flexible framework for content description of digital resources that serves needs of libraries
  • fit with emerging database technologies enabling institutions to introduce efficiencies in data capture and storage retrieval
  • evolving cataloguing principles from AACR2R with rules carried over or adapted to RDA


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