Index Medicus (
IM) was a comprehensive
bibliographic index of
scientific journal articles focusing on
medical science fields, published from 1879 to 2004. It was initiated by
John Shaw Billings, head of the
Library of the Surgeon General's Office,
United States Army. This library later evolved into the
United States National Library of Medicine (NLM). In the 1960s, the NLM began computerizing the indexing work by creating
MEDLARS, a
bibliographic database, which became
MEDLINE.
Index Medicus thus became the print presentation of the MEDLINE database's content, which users accessed usually by visiting a
library which subscribed to
Index Medicus (for example, a university scientist at the
university library). It continued in this role through the 1980s and 1990s, while various electronic presentations of MEDLINE's content also evolved, first with proprietary online services (accessed mostly at libraries) and later with
CD-ROMs, then with
Entrez and
PubMed. As users gradually migrated from print to online use,
Index Medicus print subscriptions dwindled. During the 1990s, the dissemination of home internet connections, the launch of the
Web and
web browsers, and the launch of
PubMed greatly accelerated the shift of online access to MEDLINE from something one did at the library to something one did anywhere. This dissemination, along with the superior usability of
search compared with use of a print index in serving the user's purpose (which is to distill relevant subsets of information from a vast superset), caused the use of MEDLINE's print output,
Index Medicus, to drop precipitously. In 2004, print publication ceased. In one sense,
Index Medicus and
Abridged Index Medicus still exist conceptually as
content curation services that curate MEDLINE content into search subsets or
database views (in other words, subsets of MEDLINE
records from some journals but not others). This filters search results with a view toward excluding poor-quality articles (such as by excluding
junk journals), which is often helpful depending on the needs of the user.