Backfile reveals biomedical history

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The EMBASE bibliographic database from Elsevier is one of the latest products to have its whole archive digitised. Magdaleine Margaritis, marketing manager of the company's Pharma Development Group, tells Sian Harris why

What is EMBASE?

The EMBASE biomedical and pharmacological bibliographic database provides access to the most up-to-date citations and abstracts from biomedical and drug literature. It contains over 11 million records from 1974 to the present, with more than 600,000 additions annually.

The history of EMBASE begins with the launch of the Excerpta Medica (EM) Abstract Journals. EM was founded in 1946 in Amsterdam by a group of Dutch physicians to promote the flow of medical information following the Second World War. Initially EM published 13 abstract journal sections divided along the lines of the medical school curriculum, including anatomy, pathology, physiology, internal medicine and other basic scientific and clinical specialties. In 1972, it joined the Elsevier Group and electronic access became a reality when EMBASE, the Excerpta Medica database, was launched in 1974.

Why did you digitise the backfile?

Feedback from the EMBASE user community clearly indicated the importance of preserving the Excerpta Medica abstract records published in print prior to the advent of the EMBASE online file. Having these records ‘alive’ once again opens up a window to look back at seminal research that serves as the foundation of many of today’s advancements and to document the history of the life sciences.

A sample record from the backfile

EMBASE Classic now makes the EMBASE backfile from 1947 to 1973 accessible in electronic format for the first time. The fully-digitised backfile is drawn from 43 Excerpta Medica Abstract Journal print volume titles, and includes 1.8 million records. The EMBASE Classic release enables institutional subscribers to obtain perpetual access to this information.

The backfile, when used with the EMBASE file, enables effective and efficient searching of a single file from 1947 until today, controlled by a single thesaurus. For example, an important benefit of the addition of EMBASE Classic to EMBASE is the documentation of toxicities and adverse effects that have been published about drugs or endogenous compounds at the time. These drugs may be revisited today or serve as controls because of their known adverse effects or specific effects in animals. In addition, results of clinical trials published prior to 1974 can now be more easily factored into evidence-based medical assessments.

How did you digitise the backfile?

In order to build EMBASE Classic, a microfilm repository of the 43 Excerpta Medica Abstract Journals issues published between 1947 and 1973 was scanned. This took eight months.

Aside from the task of locating all issues, one of the major challenges was indexing. Elsevier was determined to implement its EMTREE thesaurus, which contains over 52,000 preferred terms and more than 210,000 synonyms.

The value of the ‘historic’ index terms in EMBASE Classic is that they are based on the full-text article. They therefore supplement the information contained in the titles and abstracts of EMBASE Classic records. In many cases, however, these terms are inappropriate for webbased searching because outdated terminology might have been used or the terminology might not adhere to EMBASE’s indexing policy. In order to increase recall and precision searching of the archived literature, additional index terms have been added to each record in EMBASE Classic by automatic indexing. In addition, historic index terms have been mapped to the current EMTREE. The average number of new index terms included in each EMBASE Classic record is 11. For example, the pre-penicillin era drugs oxophenarsine (tradename mapharsen) and thiazosulfone (tradename promizole) have now become EMTREE terms.

This means current EMTREE terms can be used to search EMBASE Classic in combination with EMBASE and that ‘Drug terms’ and ‘medical terms’ can be searched separately. In addition, CAS registry numbers are included in records enhanced with drug index terms and DOIs are included in records for which the full-text source article is available online.

How is it accessed?

Agreements with Ovid, Dialog and DataStar make EMBASE Classic available via the same major platforms as EMBASE, so users can search across both files. EMBASE Classic may also be licensed directly from Elsevier. Availability via additional vendors is being investigated. EMBASE Classic will become available on the platform in summer 2008.